Patent Application
20220403475
A Sequence Listing in ASCII text format, submitted under 37 C.F.R. § 1.821, entitled 1499-59_ST25, 436,265 bytes in size, generated on Jun. 9, 2022, and filed via EFS-Web, is provided in lieu of a paper copy. This Sequence Listing is hereby incorporated herein by reference into the specification for its disclosures.
The invention relates to nucleic acid constructs useful as a reporter, compositions and systems comprising the same, and methods of use of such constructs, compositions and/or systems.
Numerous genome-editing tools have been developed since the discovery and widespread adaptation of CRISPR/Cas technology. These tools generate different modifications to DNA. However, it can be difficult to determine their activity in non-model organisms because of intractability in protein or vector delivery and assessment and quantification of editing efficiency. Therefore, surrogate reporters that report on the activity of genome editing tools would be advantageous.
Several plasmid reporters have been made. Such examples include the ‘Traffic Light Reporter’ (Nat Methods. 2011 Jul. 10;8(8):671-6. doi: 10.1038/nmeth.1648.) and variations thereof (e.g., Nat Methods. 2011 Oct 9;8(11):941-3), which use a gene expression system containing fluorescent proteins. Guide RNAs targeting the coding region of the fluorescent protein are used to target the editing enzyme to the reporter plasmid. Activity of the editing enzyme (i.e., indel generation from nuclease activity) causes DNA changes (such as a frameshift mutation) that change the fluorescent state of the reporter, which is usually detected using a flow cytometer. Thus, the Traffic Light Reporter has been used to quantify the activity of indel generation and homologous recombination (HR) efficiency.
Another plasmid-based reporter system uses mCherry fluorescence output (Knudsen et al. Front Cell Dev Biol. 2018; 6(54):1-10). In this system, a spacer of interest with NGG PAM (23 bases total) is inserted at the N-terminus of mCherry out-of-frame. Therefore, when the plasmid is targeted by a CRISPR editing enzyme (e.g., Cas9) and induces a frameshift mutation, mCherry will be in-frame and can be detected.
Each of the above-described reporters rely on either targeting and editing the gene encoding the fluorescent protein or a 20-23 bp-sequence that is targeted by the CRISPR editing enzyme (Knudsen et al.). This is not ideal because some editing systems (e.g., editing tools such as Prime Editing (Anzalone et al, Nature, 576, 149-157 (2019))) show variable activity depending on the target sequence it acts on. For example, in the case of Prime Editing, the editor construct requires a careful design of its RNA component that includes large RNA homology sequences around the 20-bp Cas9 spacer sequence in the target DNA sequence, which is impossible to do with existing reporters based on fluorescent protein targeting or introduction of 20-23 bp spacer upstream of the fluorescent protein. Thus, the reporter in these systems is not mimicking the exact condition in which the editing system is intended to be used and, as such, the efficiency of the editing system cannot be measured by targeting the reporter sequences or by targeting a spacer sequence without the broad sequence context associated with the host genome to be edited.
One aspect of the present invention is directed to a nucleic acid construct comprising: a promoter; a first nucleic acid including a target sequence; and a second nucleic acid encoding a polypeptide (e.g., a fluorescent polypeptide), wherein the promoter is operably associated with the first and second nucleic acids and the first nucleic acid is between the promoter and the second nucleic acid, and wherein the first nucleic acid includes a stop codon (e.g., TGA, TAG, and/or TAA) that prevents translation of the second nucleic acid or the first nucleic acid includes a codon (e.g., a UGG codon) that, upon modification (e.g., an in frame modification) of the codon to a stop codon, prevents translation of the second nucleic acid. One or more (e.g., 1, 2, 3, 4, or more) stop codon(s) may be present in the first nucleic acid.
Another aspect of the present invention is directed to a nucleic acid construct comprising: a promoter; a first nucleic acid including a target sequence; and a second nucleic acid encoding a recombinase (e.g., a Cre recombinase), wherein the promoter is operably associated with the first and second nucleic acids and the first nucleic acid is between the promoter and the second nucleic acid, and wherein the first nucleic acid includes a stop codon (e.g., TGA, TAG, and/or TAA) that prevents translation of the second nucleic acid or the first nucleic acid includes a codon (e.g., a UGG codon) that, upon modification of the codon to a stop codon, prevents translation of the second nucleic acid. One or more (e.g., 1, 2, 3, 4, or more) stop codon(s) may be present in the first nucleic acid.
A further aspect of the present invention is directed to a method of detecting modification of a target sequence and/or target nucleic acid, the method comprising: providing a nucleic acid construct including: a promoter; a first nucleic acid including the target sequence; and a second nucleic acid encoding a polypeptide (e.g., a fluorescent polypeptide) that provides a detectable signal (e.g., a fluorescent signal), wherein the promoter is operably associated with the first and second nucleic acids and the first nucleic acid is between the promoter and the second nucleic acid, and wherein the first nucleic acid includes a stop codon (e.g., TGA, TAG, and/or TAA) that prevents translation of the second nucleic acid or the first nucleic acid includes a codon (e.g., a UGG codon) that, upon modification of the codon to a stop codon, prevents translation of the second nucleic acid; contacting an editing system and the target sequence, wherein, responsive to modification of the target sequence, the detectable signal appears or is reduced; and detecting the appearance or a reduction of the detectable signal, thereby detecting modification of the target sequence and/or target nucleic acid.
Another aspect of the present invention is directed to a method of detecting modification of a target sequence and/or target nucleic acid, the method comprising: providing a nucleic acid construct including: a promoter; a first nucleic acid including a target sequence; and a second nucleic acid encoding a recombinase (e.g., a Cre recombinase), wherein the promoter is operably associated with the first and second nucleic acids and the first nucleic acid is between the promoter and the second nucleic acid, and wherein the first nucleic acid includes a stop codon (e.g., TGA, TAG, and/or TAA) that prevents translation of the second nucleic acid or the first nucleic acid includes a codon (e.g., a UGG codon) that, upon modification of the codon to a stop codon, prevents translation of the second nucleic acid; contacting an editing system and the target sequence, wherein, responsive to modification of the target sequence, a detectable signal (e.g., a fluorescent signal) appears; and detecting the appearance of the detectable signal, thereby detecting modification of the target sequence and/or target nucleic acid.
A further aspect of the present invention is directed to a method of determining and/or measuring the efficiency and/or effectiveness of a first editing system and/or a component thereof in modifying a target sequence and/or target nucleic acid, the method comprising: providing a nucleic acid construct including: a promoter; a first nucleic acid including the target sequence; and a second nucleic acid encoding a polypeptide (e.g., a fluorescent polypeptide) that provides a first detectable signal (e.g., a fluorescent signal), wherein the promoter is operably associated with the first and second nucleic acids and the first nucleic acid is between the promoter and the second nucleic acid, and wherein the first nucleic acid includes a stop codon (e.g., TGA, TAG, and/or TAA) that prevents translation of the second nucleic acid or the first nucleic acid includes a codon (e.g., a UGG codon) that, upon modification of the codon to a stop codon, prevents translation of the second nucleic acid; contacting the first editing system and the target sequence, wherein, responsive to modification of the target sequence, the first detectable signal appears or is reduced; and measuring the frequency and/or amount (e.g., intensity) of the first detectable signal to provide a first signal amount; separately contacting a second editing system and the target sequence, wherein, responsive to modification of the target sequence, a second detectable signal appears or is reduced, and wherein the first editing system is different than the second editing system; measuring the frequency and/or amount (e.g., intensity) of the second detectable signal to provide a second signal amount; and comparing the first signal amount to the second signal amount, wherein a greater amount for the first signal amount compared to the second signal amount indicates an increased efficiency and/or effectiveness of the first editing system and/or a component thereof in modifying the target sequence and/or target nucleic acid.
Another aspect of the present invention is directed to a method of determining and/or measuring the efficiency and/or effectiveness of a first editing system and/or a component thereof in modifying a target sequence and/or target nucleic acid, the method comprising: providing a nucleic acid construct including: a promoter; a first nucleic acid including a target sequence; and a second nucleic acid encoding a recombinase (e.g., a Cre recombinase), wherein the promoter is operably associated with the first and second nucleic acids and the first nucleic acid is between the promoter and the second nucleic acid, and wherein the first nucleic acid includes a stop codon (e.g., TGA, TAG, and/or TAA) that prevents translation of the second nucleic acid or the first nucleic acid includes a codon (e.g., a UGG codon) that, upon modification of the codon to a stop codon, prevents translation of the second nucleic acid; contacting the first editing system and the target sequence, wherein, responsive to modification of the target sequence, a first detectable signal (e.g., a fluorescent signal) appears; measuring the frequency and/or amount (e.g., intensity) of the first detectable signal to provide a first signal amount; separately contacting a second editing system and the target sequence, wherein, responsive to modification of the target sequence, a second detectable signal appears, and wherein the first editing system is different than the second editing system; measuring the frequency and/or amount (e.g., intensity) of the second detectable signal to provide a second signal amount; and comparing the first signal amount to the second signal amount, wherein a greater amount for the first signal amount compared to the second signal amount indicates an increased efficiency and/or effectiveness of the first editing system and/or a component thereof in modifying the target sequence and/or target nucleic acid.
The present invention further provides expression cassettes and/or vectors comprising nucleic acid(s) of the invention and/or nucleic acids encoding protein(s) of the invention. In addition, the invention provides cells comprising the compositions, polypeptides (e.g., chimeric proteins), nucleic acids (e.g., chimeric nucleic acids), expression cassettes, and/or vectors of the present invention. Additionally, the invention provides kits comprising a composition, polypeptide, nucleic acid, expression cassette, and/or vector of the present invention and/or cells comprising the same.
It is noted that aspects of the invention described with respect to one embodiment, may be incorporated in a different embodiment although not specifically described relative thereto. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination. Applicant reserves the right to change any originally filed claim and/or file any new claim accordingly, including the right to be able to amend any originally filed claim to depend from and/or incorporate any feature of any other claim or claims although not originally claimed in that manner. These and other objects and/or aspects of the present invention are explained in detail in the specification set forth below. Further features, advantages and details of the present invention will be appreciated by those of ordinary skill in the art from a reading of the figures and the detailed description of the preferred embodiments that follow, such description being merely illustrative of the present invention.
The present invention now will be described hereinafter with reference to the accompanying drawings and examples, in which embodiments of the invention are shown. This description is not intended to be a detailed catalog of all the different ways in which the invention may be implemented, or all the features that may be added to the instant invention. For example, features illustrated with respect to one embodiment may be incorporated into other embodiments, and features illustrated with respect to a particular embodiment may be deleted from that embodiment. Thus, the invention contemplates that in some embodiments of the invention, any feature or combination of features set forth herein can be excluded or omitted. In addition, numerous variations and additions to the various embodiments suggested herein will be apparent to those skilled in the art in light of the instant disclosure, which do not depart from the instant invention. Hence, the following descriptions are intended to illustrate some particular embodiments of the invention, and not to exhaustively specify all permutations, combinations and variations thereof.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
All publications, patent applications, patents and other references cited herein are incorporated by reference in their entireties for the teachings relevant to the sentence and/or paragraph in which the reference is presented.
Unless the context indicates otherwise, it is specifically intended that the various features of the invention described herein can be used in any combination. Moreover, the present invention also contemplates that in some embodiments of the invention, any feature or combination of features set forth herein can be excluded or omitted. To illustrate, if the specification states that a composition comprises components A, B and C, it is specifically intended that any of A, B or C, or a combination thereof, can be omitted and disclaimed singularly or in any combination.
As used in the description of the invention and the appended claims, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise.
Also as used herein, “and/or” refers to and encompasses any and all possible combinations of one or more of the associated listed items, as well as the lack of combinations when interpreted in the alternative (“or”).
The term “about,” as used herein when referring to a measurable value such as an amount or concentration and the like, is meant to encompass variations of ±10%, ±5%, ±1%, ±0.5%, or even ±0.1% of the specified value as well as the specified value. For example, “about X” where X is the measurable value, is meant to include X as well as variations of ±10%, ±5%, ±1%, ±0.5%, or even ±0.1% of X. A range provided herein for a measurable value may include any other range and/or individual value therein.
As used herein, phrases such as “between X and Y” and “between about X and Y” should be interpreted to include X and Y. As used herein, phrases such as “between about X and Y” mean “between about X and about Y” and phrases such as “from about X to Y” mean “from about X to about Y.”
Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. For example, if the range 10 to 15 is disclosed, then 11, 12, 13, and 14 are also disclosed.
The term “comprise,” “comprises” and “comprising” as used herein, specify the presence of the stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
As used herein, the transitional phrase “consisting essentially of” means that the scope of a claim is to be interpreted to encompass the specified materials or steps recited in the claim and those that do not materially affect the basic and novel characteristic(s) of the claimed invention. Thus, the term “consisting essentially of” when used in a claim of this invention is not intended to be interpreted to be equivalent to “comprising.”
As used herein, the terms “increase,” “increasing,” “enhance,” “enhancing,” “improve” and “improving” (and grammatical variations thereof) describe an elevation of at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, 150%, 200%, 300%, 400%, 500% or more such as compared to another measurable property or quantity (e.g., a control value).
As used herein, the terms “reduce,” “reduced,” “reducing,” “reduction,” “diminish,” and “decrease” (and grammatical variations thereof), describe, for example, a decrease of at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 97%, 98%, 99%, or 100% such as compared to another measurable property or quantity (e.g., a control value). In some embodiments, the reduction can result in no or essentially no (i.e., an insignificant amount, e.g., less than about 10% or even 5%) detectable activity or amount.
A “heterologous nucleotide sequence” or a “recombinant nucleotide sequence” is a nucleotide sequence not naturally associated with a host cell into which it is introduced, including non-naturally occurring multiple copies of a naturally occurring nucleotide sequence.
A “native” or “wild-type” nucleic acid, nucleotide sequence, polypeptide or amino acid sequence refers to a naturally occurring or endogenous nucleic acid, nucleotide sequence, polypeptide or amino acid sequence. Thus, for example, a “native nucleic acid” is a nucleic acid that is naturally occurring in or endogenous to a reference organism. A “homologous” nucleic acid sequence is a nucleotide sequence naturally associated with a host cell into which it is introduced.
As used herein, the terms “nucleic acid,” “nucleic acid molecule,” “nucleotide sequence” and “polynucleotide” refer to RNA or DNA that is linear or branched, single or double stranded, or a hybrid thereof. The term also encompasses RNA/DNA hybrids. When dsRNA is produced synthetically, less common bases, such as inosine, 5-methylcytosine, 6-methyladenine, hypoxanthine and others can also be used for antisense, dsRNA, and ribozyme pairing. For example, polynucleotides that contain C-5 propyne analogues of uridine and cytidine have been shown to bind RNA with high affinity and to be potent antisense inhibitors of gene expression. Other modifications, such as modification to the phosphodiester backbone, or the 2′-hydroxy in the ribose sugar group of the RNA can also be made.
As used herein, the term “nucleotide sequence” refers to a heteropolymer of nucleotides or the sequence of these nucleotides from the 5′ to 3′ end of a nucleic acid molecule and includes DNA or RNA molecules, including cDNA, a DNA fragment or portion, genomic DNA, synthetic (e.g., chemically synthesized) DNA, plasmid DNA, mRNA, and anti-sense RNA, any of which can be single stranded or double stranded. The terms “nucleotide sequence” “nucleic acid,” “nucleic acid molecule,” “nucleic acid construct,” “recombinant nucleic acid,” “oligonucleotide” and “polynucleotide” are also used interchangeably herein to refer to a heteropolymer of nucleotides. Nucleic acid molecules and/or nucleotide sequences provided herein are presented herein in the 5′ to 3′ direction, from left to right and are represented using the standard code for representing the nucleotide characters as set forth in the U.S. sequence rules, 37 CFR §§ 1.821-1.825 and the World Intellectual Property Organization (WIPO) Standard ST.25. A “5′ region” as used herein can mean the region of a polynucleotide that is nearest the 5′ end of the polynucleotide. Thus, for example, an element in the 5′ region of a polynucleotide can be located anywhere from the first nucleotide located at the 5′ end of the polynucleotide to the nucleotide located halfway through the polynucleotide. A “3′ region” as used herein can mean the region of a polynucleotide that is nearest the 3′ end of the polynucleotide. Thus, for example, an element in the 3′ region of a polynucleotide can be located anywhere from the first nucleotide located at the 3′ end of the polynucleotide to the nucleotide located halfway through the polynucleotide.
As used herein, the term “gene” refers to a nucleic acid molecule capable of being used to produce mRNA, antisense RNA, miRNA, anti-microRNA antisense oligodeoxyribonucleotide (AMO) and the like. Genes may or may not be capable of being used to produce a functional protein or gene product. Genes can include both coding and non-coding regions (e.g., introns, regulatory elements, promoters, enhancers, termination sequences and/or 5′ and 3′ untranslated regions).
A polynucleotide, gene, or polypeptide may be “isolated” by which is meant a nucleic acid or polypeptide that is substantially or essentially free from components normally found in association with the nucleic acid or polypeptide, respectively, in its natural state. In some embodiments, such components include other cellular material, culture medium from recombinant production, and/or various chemicals used in chemically synthesizing the nucleic acid or polypeptide.
The term “mutation” refers to point mutations (e.g., missense, or nonsense, or insertions or deletions of single base pairs that result in frame shifts), insertions, deletions, and/or truncations. When the mutation is a substitution of a residue within an amino acid sequence with another residue, or a deletion or insertion of one or more residues within a sequence, the mutations are typically described by identifying the original residue followed by the position of the residue within the sequence and by the identity of the newly substituted residue.
The terms “complementary” or “complementarity,” as used herein, refer to the natural binding of polynucleotides under permissive salt and temperature conditions by base-pairing. For example, the sequence “A-G-T” (5′ to 3′) binds to the complementary sequence “T-C-A” (3′ to 5′). Complementarity between two single-stranded molecules may be “partial,” in which only some of the nucleotides bind, or it may be complete when total complementarity exists between the single stranded molecules. The degree of complementarity between nucleic acid strands has significant effects on the efficiency and strength of hybridization between nucleic acid strands.
“Complement” as used herein can mean 100% complementarity with the comparator nucleotide sequence or it can mean less than 100% complementarity (e.g., “substantially complementary” such as about 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, and the like, complementarity).
A “portion” or “fragment” of a nucleotide sequence or polypeptide (including a domain) will be understood to mean a nucleotide sequence or polypeptide of reduced length (e.g., reduced by 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or more residue(s) (e.g., nucleotide(s) or peptide(s)) relative to a reference nucleotide sequence or polypeptide, respectively, and comprising, consisting essentially of and/or consisting of a nucleotide sequence or polypeptide of contiguous residues, respectively, identical or almost identical (e.g., 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% identical) to the reference nucleotide sequence or polypeptide. In some embodiments, a portion of a reference nucleotide sequence or polypeptide is about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 97%, 98%, 99%, or more of the full-length reference nucleotide sequence or polypeptide. Such a nucleic acid fragment or portion according to the invention may be, where appropriate, included in a larger polynucleotide of which it is a constituent. As an example, a repeat sequence of guide nucleic acid of this invention may comprise a portion of a wild-type CRISPR-Cas repeat sequence (e.g., a wild-type Type V CRISR Cas repeat; e.g., a repeat from the CRISPR Cas system that includes, but is not limited to, a Cas9, Cas12a (Cpf1), Cas12b, Cas12c (C2c3), Cas12d (CasY), Cas12e (CasX), Cas12g, Cas12h, Cas12i, C2c1, C2c4, C2c5, C2c8, C2c9, C2c10, Cas14a, Cas14b, and/or Cas14c, and the like).
Different nucleic acids or proteins having homology are referred to herein as “homologues.” The term homologue includes homologous sequences from the same and other species and orthologous sequences from the same and other species. “Homology” refers to the level of similarity between two or more nucleic acid and/or amino acid sequences in terms of percent of positional identity (i.e., sequence similarity or identity). Homology also refers to the concept of similar functional properties among different nucleic acids or proteins. Thus, the compositions and methods of the invention further comprise homologues to the nucleotide sequences and polypeptides of this invention. “Orthologous” and “orthologs” as used herein, refers to homologous nucleotide sequences and/or amino acid sequences in different species that arose from a common ancestral gene during speciation. A homologue or ortholog of a nucleotide sequence of this invention has a substantial sequence identity (e.g., at least about 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5% or 100%) to said nucleotide sequence of the invention.
As used herein “sequence identity” refers to the extent to which two optimally aligned polynucleotide or polypeptide sequences are invariant throughout a window of alignment of components, e.g., nucleotides or amino acids. “Identity” can be readily calculated by known methods including, but not limited to, those described in: Computational Molecular Biology (Lesk, A. M., ed.) Oxford University Press, New York (1988); Biocomputing: Informatics and Genome Projects (Smith, D. W., ed.) Academic Press, New York (1993); Computer Analysis of Sequence Data, Part I (Griffin, A. M., and Griffin, H. G., eds.) Humana Press, New Jersey (1994); Sequence Analysis in Molecular Biology (von Heinje, G., ed.) Academic Press (1987); and Sequence Analysis Primer (Gribskov, M. and Devereux, J., eds.) Stockton Press, New York (1991).
As used herein, the term “percent sequence identity” or “percent identity” refers to the percentage of identical nucleotides in a linear polynucleotide sequence of a reference (“query”) polynucleotide molecule (or its complementary strand) as compared to a test (“subject”) polynucleotide molecule (or its complementary strand) when the two sequences are optimally aligned. In some embodiments, “percent identity” can refer to the percentage of identical amino acids in an amino acid sequence as compared to a reference polypeptide.
As used herein, the phrase “substantially identical,” or “substantial identity” in the context of two nucleic acid molecules, nucleotide sequences or protein sequences, refers to two or more sequences or subsequences that have at least about 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5% or 100% nucleotide or amino acid residue identity, when compared and aligned for maximum correspondence, as measured using one of the following sequence comparison algorithms or by visual inspection. In some embodiments of the invention, the substantial identity exists over a region of consecutive nucleotides of a nucleotide sequence of the invention that is about 10 nucleotides to about 20 nucleotides, about 10 nucleotides to about 25 nucleotides, about 10 nucleotides to about 30 nucleotides, about 15 nucleotides to about 25 nucleotides, about 30 nucleotides to about 40 nucleotides, about 50 nucleotides to about 60 nucleotides, about 70 nucleotides to about 80 nucleotides, about 90 nucleotides to about 100 nucleotides, or more nucleotides in length, and any range therein, up to the full length of the sequence. In some embodiments, the nucleotide sequences can be substantially identical over at least about 20 nucleotides (e.g., about 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40 nucleotides). In some embodiments, a substantially identical nucleotide or protein sequence performs substantially the same function as the nucleotide (or encoded protein sequence) to which it is substantially identical.
For sequence comparison, typically one sequence acts as a reference sequence to which test sequences are compared. When using a sequence comparison algorithm, test and reference sequences are entered into a computer, subsequence coordinates are designated if necessary, and sequence algorithm program parameters are designated. The sequence comparison algorithm then calculates the percent sequence identity for the test sequence(s) relative to the reference sequence, based on the designated program parameters.
Optimal alignment of sequences for aligning a comparison window are well known to those skilled in the art and may be conducted by tools such as the local homology algorithm of Smith and Waterman, the homology alignment algorithm of Needleman and Wunsch, the search for similarity method of Pearson and Lipman, and optionally by computerized implementations of these algorithms such as GAP, BESTFIT, FASTA, and TFASTA available as part of the GCG® Wisconsin Package® (Accelrys Inc., San Diego, Calif.). An “identity fraction” for aligned segments of a test sequence and a reference sequence is the number of identical components which are shared by the two aligned sequences divided by the total number of components in the reference sequence segment, e.g., the entire reference sequence or a smaller defined part of the reference sequence. Percent sequence identity is represented as the identity fraction multiplied by 100. The comparison of one or more polynucleotide sequences may be to a full-length polynucleotide sequence or a portion thereof, or to a longer polynucleotide sequence. For purposes of this invention “percent identity” may also be determined using BLASTX version 2.0 for translated nucleotide sequences and BLASTN version 2.0 for polynucleotide sequences.
Two nucleotide sequences may also be considered substantially complementary when the two sequences hybridize to each other under stringent conditions. In some representative embodiments, two nucleotide sequences considered to be substantially complementary hybridize to each other under highly stringent conditions.
“Stringent hybridization conditions” and “stringent hybridization wash conditions” in the context of nucleic acid hybridization experiments such as Southern and Northern hybridizations are sequence dependent, and are different under different environmental parameters. An extensive guide to the hybridization of nucleic acids is found in Tijssen Laboratory Techniques in Biochemistry and Molecular Biology-Hybridization with Nucleic Acid Probes part I chapter 2 “Overview of principles of hybridization and the strategy of nucleic acid probe assays” Elsevier, New York (1993). Generally, highly stringent hybridization and wash conditions are selected to be about 5° C. lower than the thermal melting point (Tm) for the specific sequence at a defined ionic strength and pH.
The Tm is the temperature (under defined ionic strength and pH) at which 50% of the target sequence hybridizes to a perfectly matched probe. Very stringent conditions are selected to be equal to the Tm for a particular probe. An example of stringent hybridization conditions for hybridization of complementary nucleotide sequences which have more than 100 complementary residues on a filter in a Southern or northern blot is 50% formamide with 1 mg of heparin at 42° C., with the hybridization being carried out overnight. An example of highly stringent wash conditions is 0.1 5M NaCl at 72° C. for about 15 minutes. An example of stringent wash conditions is a 0.2×SSC wash at 65° C. for 15 minutes (see, Sambrook, infra, for a description of SSC buffer). Often, a high stringency wash is preceded by a low stringency wash to remove background probe signal. An example of a medium stringency wash for a duplex of, e.g., more than 100 nucleotides, is 1×SSC at 45° C. for 15 minutes. An example of a low stringency wash for a duplex of, e.g., more than 100 nucleotides, is 4-6×SSC at 40° C. for 15 minutes. For short probes (e.g., about 10 to 50 nucleotides), stringent conditions typically involve salt concentrations of less than about 1.0 M Na ion, typically about 0.01 to 1.0 M Na ion concentration (or other salts) at pH 7.0 to 8.3, and the temperature is typically at least about 30° C. Stringent conditions can also be achieved with the addition of destabilizing agents such as formamide. In general, a signal to noise ratio of 2× (or higher) than that observed for an unrelated probe in the particular hybridization assay indicates detection of a specific hybridization. Nucleotide sequences that do not hybridize to each other under stringent conditions are still substantially identical if the proteins that they encode are substantially identical. This can occur, for example, when a copy of a nucleotide sequence is created using the maximum codon degeneracy permitted by the genetic code.
A polynucleotide and/or recombinant nucleic acid construct of this invention can be codon optimized for expression. In some embodiments, a polynucleotide, nucleic acid construct, expression cassette, and/or vector of the invention (e.g., that comprises/encodes a nucleic acid binding polypeptide (e.g., a DNA binding polypeptide such as a sequence-specific DNA binding domain from a polynucleotide-guided endonuclease, a zinc finger nuclease, a transcription activator-like effector nucleases (TALEN), an endonuclease (e.g. Fok1), an Argonaute protein, and/or a CRISPR-Cas effector protein (e.g., a Type I CRISPR-Cas effector protein, a Type II CRISPR-Cas effector protein, a Type III CRISPR-Cas effector protein, a Type IV CRISPR-Cas effector protein, a Type V CRISPR-Cas effector protein or a Type VI CRISPR-Cas effector protein))), a domain capable of interacting with a T-DNA sequence (e.g., Agrobacterium effector proteins; e.g., VirD2 and/or VirE2), a T-DNA sequence, affinity polypeptides, peptide tags, RNA recruiting motifs, fusion proteins, a DNA-dependent DNA polymerase a guide nucleic acid, a cytosine deaminase, adenine deaminase and/or the like) may be codon optimized for expression in an organism (e.g., an animal, a plant, a fungus, an archaeon, or a bacterium). In some embodiments, the codon optimized nucleic acid constructs, polynucleotides, expression cassettes, and/or vectors of the invention have about 70% to about 99.9% (e.g., 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%. 99.9% or 100%) identity or more to the reference nucleic acid constructs, polynucleotides, expression cassettes, and/or vectors but which have not been codon optimized.
In any of the embodiments described herein, a polynucleotide or nucleic acid construct of the invention may be operatively associated with a variety of promoters and/or other regulatory elements for expression in an organism or cell thereof (e.g., a mammal and/or a mammalian cell, a plant and/or a cell of a plant). Thus, in some embodiments, a polynucleotide or nucleic acid construct of this invention may further comprise one or more promoters, introns, enhancers, and/or terminators operably linked to one or more nucleotide sequences. In some embodiments, a promoter may be operably associated with an intron (e.g., Ubi1 promoter and intron). In some embodiments, a promoter associated with an intron maybe referred to as a “promoter region” (e.g., Ubi1 promoter and intron).
By “operably linked” or “operably associated” as used herein in reference to polynucleotides, it is meant that the indicated elements are functionally related to each other, and are also generally physically related. Thus, the term “operably linked” or “operably associated” as used herein, refers to nucleotide sequences on a single nucleic acid molecule that are functionally associated. Thus, a first nucleotide sequence that is operably linked to a second nucleotide sequence means a situation when the first nucleotide sequence is placed in a functional relationship with the second nucleotide sequence. For instance, a promoter is operably associated with a nucleotide sequence if the promoter effects the transcription or expression of said nucleotide sequence. Those skilled in the art will appreciate that the control sequences (e.g., promoter) need not be contiguous with the nucleotide sequence to which it is operably associated, as long as the control sequences function to direct the expression thereof. Thus, for example, intervening untranslated, yet transcribed, nucleic acid sequences can be present between a promoter and the nucleotide sequence, and the promoter can still be considered “operably linked” to the nucleotide sequence.
As used herein, the term “linked” or “fused” in reference to polypeptides, refers to the attachment of one polypeptide to another. A polypeptide may be linked or fused to another polypeptide (at the N-terminus or the C-terminus) directly (e.g., via a peptide bond) or through a linker (e.g., a peptide linker).
The term “linker” in reference to polypeptides is art-recognized and refers to a chemical group, or a molecule linking two molecules or moieties, e.g., two domains of a fusion protein, such as, for example, a CRISPR-Cas effector protein and a peptide tag and/or an Agrobacterium effector protein and an affinity polypeptide that binds to the peptide tag. A linker may be comprised of a single linking molecule (e.g., a single amino acid) or may comprise more than one linking molecule. In some embodiments, the linker can be an organic molecule, group, polymer, or chemical moiety such as a bivalent organic moiety. In some embodiments, the linker may be an amino acid or it may be a peptide. In some embodiments, the linker is a peptide.
In some embodiments, a peptide linker useful with this invention may be about 2 to about 100 or more amino acids in length, for example, about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100 or more amino acids in length (e.g., about 2 to about 40, about 2 to about 50, about 2 to about 60, about 4 to about 40, about 4 to about 50, about 4 to about 60, about 5 to about 40, about 5 to about 50, about 5 to about 60, about 9 to about 40, about 9 to about 50, about 9 to about 60, about 10 to about 40, about 10 to about 50, about 10 to about 60, or about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 amino acids to about 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100 or more amino acids in length (e.g., about 105, 110, 115, 120, 130, 140 150 or more amino acids in length). In some embodiments, a peptide linker may be a GS linker.
As used herein, the term “linked,” or “fused” in reference to polynucleotides, refers to the attachment of one polynucleotide to another polynucleotide. In some embodiments, two or more polynucleotide molecules may be linked by a linker that can be an organic molecule, group, polymer, or chemical moiety such as a bivalent organic moiety. A polynucleotide may be linked or fused to another polynucleotide (at the 5′ end or the 3′ end) via a covalent or non-covenant linkage or binding, including e.g., Watson-Crick base-pairing, or through one or more linking nucleotides. In some embodiments, a polynucleotide motif of a certain structure may be inserted within another polynucleotide sequence (e.g. extension of the hairpin structure in guide RNA). In some embodiments, the linking nucleotides may be naturally occurring nucleotides. In some embodiments, the linking nucleotides may be non-naturally occurring nucleotides.
A “promoter” is a nucleotide sequence that controls or regulates the transcription of a nucleotide sequence (e.g., a coding sequence) that is operably associated with the promoter. The coding sequence controlled or regulated by a promoter may encode a polypeptide and/or a functional RNA. Typically, a “promoter” refers to a nucleotide sequence that contains a binding site for RNA polymerase II and directs the initiation of transcription. In general, promoters are found 5′, or upstream, relative to the start of the coding region of the corresponding coding sequence. A promoter may comprise other elements that act as regulators of gene expression; e.g., a promoter region. These include a TATA box consensus sequence, and often a CAAT box consensus sequence (Breathnach and Chambon, (1981)Annu. Rev. Biochem. 50:349). In plants, the CAAT box may be substituted by the AGGA box (Messing et al., (1983) in Genetic Engineering of Plants, T. Kosuge, C. Meredith and A. Hollaender (eds.), Plenum Press, pp. 211-227). In some embodiments, a promoter region may comprise at least one intron (e.g., SEQ ID NO:1 or SEQ ID NO:2).
Promoters useful with this invention can include, for example, constitutive, inducible, temporally regulated, developmentally regulated, chemically regulated, tissue-preferred and/or tissue-specific promoters for use in the preparation of recombinant nucleic acid molecules, e.g., “synthetic nucleic acid constructs” or “protein-RNA complex.” These various types of promoters are known in the art.
The choice of promoter may vary depending on the temporal and spatial requirements for expression, and also may vary based on the host cell to be transformed. Promoters for many different organisms are well known in the art. Based on the extensive knowledge present in the art, the appropriate promoter can be selected for the particular host organism of interest. Thus, for example, much is known about promoters upstream of highly constitutively expressed genes in model organisms and such knowledge can be readily accessed and implemented in other systems as appropriate.
In some embodiments, a promoter functional in a plant may be used with the constructs of this invention. Non-limiting examples of a promoter useful for driving expression in a plant include the promoter of the RubisCo small subunit gene 1 (PrbcS1), the promoter of the actin gene (Pactin), the promoter of the nitrate reductase gene (Pnr) and the promoter of duplicated carbonic anhydrase gene 1 (Pdca1) (See, Walker et al. Plant Cell Rep. 23:727-735 (2005); Li et al. Gene 403:132-142 (2007); Li et al. Mol Biol. Rep. 37:1143-1154 (2010)). PrbcS1 and Pactin are constitutive promoters and Pnr and Pdca1 are inducible promoters. Pnr is induced by nitrate and repressed by ammonium (Li et al. Gene 403:132-142 (2007)) and Pdca1 is induced by salt (Li et al. Mol Biol. Rep. 37:1143-1154 (2010)). In some embodiments, a promoter useful with this invention is RNA polymerase II (Pol II) promoter. In some embodiments, a U6 promoter or a 7SL promoter from Zea mays may be useful with constructs of this invention. In some embodiments, the U6c promoter and/or 7SL promoter from Zea mays may be useful for driving expression of a guide nucleic acid. In some embodiments, a U6c promoter, U6i promoter and/or 7SL promoter from Glycine max may be useful with constructs of this invention. In some embodiments, the U6c promoter, U6i promoter and/or 7SL promoter from Glycine max may be useful for driving expression of a guide nucleic acid.
Examples of constitutive promoters useful for plants include, but are not limited to, cestrum virus promoter (cmp) (U.S. Pat. No. 7,166,770), the rice actin 1 promoter (Wang et al. (1992) Mol. Cell. Biol. 12:3399-3406; as well as U.S. Pat. No. 5,641,876), CaMV 35S promoter (Odell et al. (1985) Nature 313:810-812), CaMV 19S promoter (Lawton et al. (1987) Plant Mol. Biol. 9:315-324), nos promoter (Ebert et al. (1987) Proc. Natl. Acad. Sci USA 84:5745-5749), Adh promoter (Walker et al. (1987) Proc. Natl. Acad. Sci. USA 84:6624-6629), sucrose synthase promoter (Yang & Russell (1990) Proc. Natl. Acad. Sci. USA 87:4144-4148), and the ubiquitin promoter. The constitutive promoter derived from ubiquitin accumulates in many cell types. Ubiquitin promoters have been cloned from several plant species for use in transgenic plants, for example, sunflower (Binet et al., 1991. Plant Science 79: 87-94), maize (Christensen et al., 1989. Plant Molec. Biol. 12: 619-632), and Arabidopsis (Norris et al. 1993. Plant Molec. Biol. 21:895-906). The maize ubiquitin promoter (UbiP) has been developed in transgenic monocot systems and its sequence and vectors constructed for monocot transformation are disclosed in the European patent publication EP 0342926. The ubiquitin promoter is suitable for the expression of the nucleotide sequences of the invention in transgenic plants, especially monocotyledons. Further, the promoter expression cassettes described by McElroy et al. (Mol. Gen. Genet. 231: 150-160 (1991)) can be easily modified for the expression of the nucleotide sequences of the invention and are particularly suitable for use in monocotyledonous hosts.
In some embodiments, tissue specific/tissue preferred promoters can be used for expression of a heterologous polynucleotide in a plant cell. Tissue specific or preferred expression patterns include, but are not limited to, green tissue specific or preferred, root specific or preferred, stem specific or preferred, flower specific or preferred or pollen specific or preferred. Promoters suitable for expression in green tissue include many that regulate genes involved in photosynthesis and many of these have been cloned from both monocotyledons and dicotyledons. In one embodiment, a promoter useful with the invention is the maize PEPC promoter from the phosphoenol carboxylase gene (Hudspeth & Grula, Plant Molec. Biol. 12:579-589 (1989)). Non-limiting examples of tissue-specific promoters include those associated with genes encoding the seed storage proteins (such as β-conglycinin, cruciferin, napin and phaseolin), zein or oil body proteins (such as oleosin), or proteins involved in fatty acid biosynthesis (including acyl carrier protein, stearoyl-ACP desaturase and fatty acid desaturases (fad 2-1)), and other nucleic acids expressed during embryo development (such as Bce4, see, e.g., Kridl et al. (1991) Seed Sci. Res. 1:209-219; as well as EP Patent No. 255378). Tissue-specific or tissue-preferential promoters useful for the expression of the nucleotide sequences of the invention in plants, particularly maize, include but are not limited to those that direct expression in root, pith, leaf or pollen. Such promoters are disclosed, for example, in WO 93/07278, incorporated by reference herein for its disclosure of promoters. Other non-limiting examples of tissue specific or tissue preferred promoters useful with the invention the cotton rubisco promoter disclosed in U.S. Pat. No. 6,040,504; the rice sucrose synthase promoter disclosed in U.S. Pat. No. 5,604,121; the root specific promoter described by de Framond (FEBS 290:103-106 (1991); European patent EP 0452269 to Ciba-Geigy); the stem specific promoter described in U.S. Pat. No. 5,625,136 (to Ciba-Geigy) and which drives expression of the maize trpA gene; the cestrum yellow leaf curling virus promoter disclosed in WO 01/73087; and pollen specific or preferred promoters including, but not limited to, ProOsLPS10 and ProOsLPS11 from rice (Nguyen et al. Plant Biotechnol. Reports 9(5):297-306 (2015)), ZmSTK2_USP from maize (Wang et al. Genome 60(6):485-495 (2017)), LAT52 and LAT59 from tomato (Twell et al. Development 109(3):705-713 (1990)), Zm13 (U.S. Pat. No. 10,421,972), PLA2-δ promoter from Arabidopsis (U.S. Pat. No. 7,141,424), and/or the ZmC5 promoter from maize (International PCT Publication No. WO 1999/042587).
Additional examples of plant tissue-specific/tissue preferred promoters include, but are not limited to, the root hair-specific cis-elements (RHEs) (Kim et al. The Plant Cell 18:2958-2970 (2006)), the root-specific promoters RCc3 (Jeong et al. Plant Physiol. 153:185-197 (2010)) and RB7 (U.S. Pat. No. 5,459,252), the lectin promoter (Lindstrom et al. (1990) Der. Genet. 11:160-167; and Vodkin (1983) Prog. Clin. Biol. Res. 138:87-98), corn alcohol dehydrogenase 1 promoter (Dennis et al. (1984) Nucleic Acids Res. 12:3983-4000), S-adenosyl-L-methionine synthetase (SAMS) (Vander Mijnsbrugge et al. (1996) Plant and Cell Physiology, 37(8):1108-1115), corn light harvesting complex promoter (Bansal et al. (1992) Proc. Natl. Acad. Sci. USA 89:3654-3658), corn heat shock protein promoter (O'Dell et al. (1985) EMBO J. 5:451-458; and Rochester et al. (1986) EMBO J. 5:451-458), pea small subunit RuBP carboxylase promoter (Cashmore, “Nuclear genes encoding the small subunit of ribulose-1,5-bisphosphate carboxylase” pp. 29-39 In: Genetic Engineering of Plants (Hollaender ed., Plenum Press 1983; and Poulsen et al. (1986)Mol. Gen. Genet. 205:193-200), Ti plasmid mannopine synthase promoter (Langridge et al. (1989) Proc. Natl. Acad. Sci. USA 86:3219-3223), Ti plasmid nopaline synthase promoter (Langridge et al. (1989), supra), petunia chalcone isomerase promoter (van Tunen et al. (1988) EMBO J. 7:1257-1263), bean glycine rich protein 1 promoter (Keller et al. (1989) Genes Dev. 3:1639-1646), truncated CaMV 35S promoter (O'Dell et al. (1985) Nature 313:810-812), potato patatin promoter (Wenzler et al. (1989) Plant Mol. Biol. 13:347-354), root cell promoter (Yamamoto et al. (1990) Nucleic Acids Res. 18:7449), maize zein promoter (Kriz et al. (1987)Mol. Gen. Genet 207:90-98; Langridge et al. (1983) Cell 34:1015-1022; Reina et al. (1990) Nucleic Acids Res. 18:6425; Reina et al. (1990) Nucleic Acids Res. 18:7449; and Wandelt et al. (1989) Nucleic Acids Res. 17:2354), globulin-1 promoter (Belanger et al. (1991) Genetics 129:863-872), α-tubulin cab promoter (Sullivan et al. (1989) Mol. Gen. Genet 215:431-440), PEPCase promoter (Hudspeth & Grula (1989) Plant Mol. Biol. 12:579-589), R gene complex-associated promoters (Chandler et al. (1989) Plant Cell 1:1175-1183), and chalcone synthase promoters (Franken et al. (1991) EMBO J. 10:2605-2612).
Useful for seed-specific expression is the pea vicilin promoter (Czako et al. (1992)Mol. Gen. Genet. 235:33-40; as well as the seed-specific promoters disclosed in U.S. Pat. No. 5,625,136. Useful promoters for expression in mature leaves are those that are switched at the onset of senescence, such as the SAG promoter from Arabidopsis (Gan et al. (1995) Science 270:1986-1988).
In addition, promoters functional in chloroplasts can be used. Non-limiting examples of such promoters include the bacteriophage T3 gene 9 5′ UTR and other promoters disclosed in U.S. Pat. No. 7,579,516. Other promoters useful with the invention include but are not limited to the S-E9 small subunit RuBP carboxylase promoter and the Kunitz trypsin inhibitor gene promoter (Kti3).
Additional regulatory elements useful with this invention include, but are not limited to, introns, enhancers, termination sequences and/or 5′ and 3′ untranslated regions.
An intron useful with this invention can be an intron identified in and isolated from a plant and then inserted into an expression cassette to be used in transformation of a plant. As would be understood by those of skill in the art, introns can comprise the sequences required for self-excision and are incorporated into nucleic acid constructs/expression cassettes in frame. An intron can be used either as a spacer to separate multiple protein-coding sequences in one nucleic acid construct, or an intron can be used inside one protein-coding sequence to, for example, stabilize the mRNA. If they are used within a protein-coding sequence, they are inserted “in-frame” with the excision sites included. Introns may also be associated with promoters to improve or modify expression. As an example, a promoter/intron combination useful with this invention includes but is not limited to that of the maize Ubi1 promoter and intron.
Non-limiting examples of introns useful with the present invention include introns from the ADHI gene (e.g., Adh1-S introns 1, 2 and 6), the ubiquitin gene (Ubi1), the RuBisCO small subunit (rbcS) gene, the RuBisCO large subunit (rbcL) gene, the actin gene (e.g., actin-1 intron), the pyruvate dehydrogenase kinase gene (pdk), the nitrate reductase gene (nr), the duplicated carbonic anhydrase gene 1 (Tdca1), the psbA gene, the atpA gene, or any combination thereof.
An “editing system” as used herein refers to any site-specific (e.g., sequence-specific) nucleic acid editing system now known or later developed, which system can introduce a modification (e.g., a mutation) in a nucleic acid in target specific manner. For example, an editing system (e.g., a site- and/or sequence-specific editing system) can include, but is not limited to, a CRISPR-Cas editing system, a meganuclease editing system, a zinc finger nuclease (ZFN) editing system, a transcription activator-like effector nuclease (TALEN) editing system, a base editing system and/or a prime editing system, each of which may comprise one or more polypeptide(s) and/or one or more polynucleotide(s) that when present and/or expressed together (e.g., as a system) in a composition and/or cell can modify (e.g., mutate) a target nucleic acid and/or a target sequence in a sequence specific manner. In some embodiments, an editing system (e.g., a site- and/or sequence-specific editing system) can comprise one or more polynucleotide(s) and/or one or more polypeptide(s), including but not limited to a nucleic acid binding polypeptide (e.g., a DNA binding domain), a nuclease, and/or other polypeptide, and/or a polynucleotide.
In some embodiments, an editing system comprises one or more sequence-specific nucleic acid binding polypeptide(s) (e.g., a DNA binding domain) that can be from, for example, a polynucleotide-guided endonuclease, a CRISPR-Cas endonuclease (e.g., CRISPR-Cas effector protein), a zinc finger nuclease, a transcription activator-like effector nuclease (TALEN) and/or an Argonaute protein. In some embodiments, an editing system comprises one or more cleavage polypeptide(s) (e.g., nucleases) including, but not limited to, an endonuclease (e.g., Fok1), a polynucleotide-guided endonuclease, a CRISPR-Cas endonuclease (e.g., CRISPR-Cas effector protein), a zinc finger nuclease, and/or a transcription activator-like effector nuclease (TALEN).
A “nucleic acid binding protein” or “nucleic acid binding polypeptide” as used herein refers to a polypeptide or domain that binds and/or is capable of binding a nucleic acid (e.g., a target nucleic acid). A DNA binding domain is an exemplary nucleic acid binding domain and may be a site- and/or sequence-specific nucleic acid binding domain. In some embodiments, a nucleic acid binding polypeptide comprises a DNA binding domain. In some embodiments, a nucleic acid binding polypeptide may be a sequence-specific nucleic acid binding polypeptide (e.g., a sequence-specific DNA binding domain) such as, but not limited to, a sequence-specific binding polypeptide and/or domain from, for example, a polynucleotide-guided endonuclease, a CRISPR-Cas effector protein (e.g., a CRISPR-Cas endonuclease), a zinc finger nuclease, a transcription activator-like effector nuclease (TALEN) and/or an Argonaute protein. In some embodiments, a nucleic acid binding polypeptide comprises a cleavage polypeptide (e.g., a nuclease polypeptide and/or domain) such as, but not limited to, an endonuclease (e.g., Fok1), a polynucleotide-guided endonuclease, a CRISPR-Cas endonuclease, a zinc finger nuclease, and/or a transcription activator-like effector nuclease (TALEN). In some embodiments, the nucleic acid binding polypeptide associates with and/or is capable of associating with (e.g., forms a complex with) one or more nucleic acid molecule(s) (e.g., forms a complex with a guide nucleic acid as described herein), which may direct and/or guide the nucleic acid binding polypeptide to a specific target nucleotide sequence (e.g., a gene locus of a genome) that is complementary to the one or more nucleic acid molecule(s) (or a portion or region thereof), thereby causing the nucleic acid binding polypeptide to bind to the nucleotide sequence at the specific target site. In some embodiments, the nucleic acid binding polypeptide is a CRISPR-Cas effector protein as described herein.
In some embodiments, an editing system comprises or is a ribonucleoprotein such as an assembled ribonucleoprotein complex (e.g., a ribonucleoprotein that comprises a CRISPR-Cas effector protein, a guide nucleic acid, and optionally a deaminase). In some embodiments, a ribonucleoprotein of an editing system may be assembled together (e.g., a pre-assembled ribonucleoprotein including a CRISPR-Cas effector protein, a guide nucleic acid, and optionally a deaminase) such as when contacted to a target nucleic acid or when introduced into a cell (e.g., a mammalian cell or a plant cell). In some embodiments, a ribonucleoprotein of an editing system may assemble into a complex (e.g., a covalently and/or non-covalently bound complex) while a portion of the ribonucleoprotein is contacting a target nucleic acid and/or may assemble after and/or during introduction into a plant cell. In some embodiments, an editing system may be assembled (e.g., into a covalently and/or non-covalently bound complex) when introduced into a plant cell. In some embodiments, a ribonucleoprotein may comprise an engineered protein of the present invention, a guide nucleic acid, and optionally a deaminase.
In some embodiments, an editing system of the present invention is used in prime editing. “Prime editing” and grammatical variants thereof as used herein refer to a nucleic acid editing technology that uses a Cas9 nickase fused to a reverse transcriptase and modifies a target nucleic acid without a double strand break or a donor DNA template. In Prime editing, the Cas9 nickase cuts the non-complementary strand of DNA upstream of the PAM site, thereby providing a 3′ flap that is extended with the extension including a modification. Further details on Prime editing can be found in Anzalone et al. (2019) Nature 576, 149-157 and/or U.S. Patent Application Publication No. 2021/0147862, the contents of each of which are incorporated herein by reference in their entirety.
In some embodiments, an editing system of the present invention incorporates the Redraw editing system. Further details on the Redraw editing system can be found in U.S. Patent Application Publication No. 2021/0130835 and/or in U.S. Patent Application Publication No. 2022/0145334.
The terms “transgene” or “transgenic” as used herein refer to at least one nucleic acid sequence that is taken from the genome of one organism or produced synthetically, and which is then introduced into a host cell (e.g., a plant cell) or organism or tissue of interest and which is subsequently integrated into the host's genome by means of “stable” transformation or transfection approaches. In contrast, the term “transient” transformation or transfection or introduction refers to a way of introducing molecular tools including at least one nucleic acid (DNA, RNA, single-stranded or double-stranded or a mixture thereof) and/or at least one amino acid sequence, optionally comprising suitable chemical or biological agents, to achieve a transfer into at least one compartment of interest of a cell, including, but not restricted to, the cytoplasm, an organelle, including the nucleus, a mitochondrion, a vacuole, a chloroplast, or into a membrane, resulting in transcription and/or translation and/or association and/or activity of the at least one molecule introduced without achieving a stable integration or incorporation into the genome and thus without inheritance of the respective at least one molecule introduced into the genome of a cell. The term “transgene-free” refers to a condition in which a transgene is not present or found in the genome of a host cell or tissue or organism of interest.
In some embodiments, a polynucleotide and/or a nucleic acid construct of the invention can be an “expression cassette” or can be comprised within an expression cassette. As used herein, “expression cassette” means a recombinant nucleic acid molecule comprising, for example, a nucleic acid construct of the invention (e.g., a polynucleotide encoding a nucleic acid binding polypeptide (e.g., a CRISPR-Cas effector protein), a polynucleotide encoding an Agrobacterium effector protein, a polynucleotide encoding a DNA dependent polymerase polypeptide or domain thereof, a polynucleotide encoding a 5′-3′ exonuclease polypeptide or domain thereof, a cytosine deaminase, a polynucleotide encoding an adenine deaminase, a polynucleotide encoding a deaminase fusion, and/or a guide nucleic acid), wherein nucleic acid construct is/are operably associated with one or more control sequences (e.g., a promoter, terminator and the like). Thus, in some embodiments, one or more expression cassettes may be provided, which are designed to express, for example, a nucleic acid construct of the invention (e.g., a nucleic acid construct of the invention encoding a nucleic acid binding polypeptide, an Agrobacterium effector protein, a DNA dependent DNA polymerase polypeptide or domain thereof, and/or 5′-3′ exonuclease polypeptide or domain thereof, and the like, or comprising a T-DNA sequence, and/or a guide nucleic acid, and the like). When an expression cassette of the present invention comprises more than one polynucleotide, the polynucleotides may be operably linked to a single promoter that drives expression of all of the polynucleotides or the polynucleotides may be operably linked to one or more separate promoters (e.g., three polynucleotides may be driven by one, two or three promoters in any combination), which may be the same or different from each other. When two or more separate promoters are used, the promoters may be the same promoter or they may be different promoters. Thus, for example, a polynucleotide encoding a CRISPR Cas effector protein and/or a deaminase and/or comprising a guide nucleic acid comprised in a single expression cassette may each be operably linked to a single promoter, may be operably linked to separate promoters, in any combination, which may be the same or different from each other.
In some embodiments, an expression cassette comprising the polynucleotides/nucleic acid constructs of the invention may be optimized for expression in an organism (e.g., an animal, a plant, a bacterium, and the like).
An expression cassette comprising a nucleic acid construct of the invention may be chimeric, meaning that at least one of its components is heterologous with respect to at least one of its other components (e.g., a promoter from the host organism operably linked to a polynucleotide of interest to be expressed in the host organism, wherein the polynucleotide of interest is from a different organism than the host or is not normally found in association with that promoter). An expression cassette may also be one that is naturally occurring but has been obtained in a recombinant form useful for heterologous expression.
An expression cassette can optionally include a transcriptional and/or translational termination region (i.e., termination region) and/or an enhancer region that is functional in the selected host cell. A variety of transcriptional terminators and enhancers are known in the art and are available for use in expression cassettes. Transcriptional terminators are responsible for the termination of transcription and correct mRNA polyadenylation. A termination region and/or the enhancer region may be native to the transcriptional initiation region, may be native to, for example, a gene encoding a nucleic acid binding protein, a gene encoding a DNA-dependent DNA polymerase, a gene encoding a domain is capable of interacting with a T-DNA sequence, and the like, or may be native to a host cell, or may be native to another source (e.g., foreign or heterologous to the promoter, to a gene encoding a nucleic acid binding protein, a gene encoding a DNA-dependent DNA polymerase, a gene encoding a domain is capable of interacting with a T-DNA sequence, and the like, or to the host cell, or any combination thereof).
An expression cassette of the invention also can include a polynucleotide encoding a selectable marker, which can be used to select a transformed host cell. As used herein, “selectable marker” means a polynucleotide sequence that when expressed imparts a distinct phenotype to the host cell expressing the marker and thus allows such transformed cells to be distinguished from those that do not have the marker. Such a polynucleotide sequence may encode either a selectable or screenable marker, depending on whether the marker confers a trait that can be selected for by chemical means, such as by using a selective agent (e.g., an antibiotic and the like), or on whether the marker is simply a trait that one can identify through observation or testing, such as by screening (e.g., fluorescence). Many examples of suitable selectable markers are known in the art and can be used in the expression cassettes described herein.
The expression cassettes, the nucleic acid molecules/constructs and polynucleotide sequences described herein can be used in connection with vectors. The term “vector” refers to a composition for transferring, delivering or introducing a nucleic acid (or nucleic acids) into a cell. A vector comprises a nucleic acid construct (e.g., expression cassette(s)) comprising the nucleotide sequence(s) to be transferred, delivered or introduced. Vectors for use in transformation of host organisms are well known in the art. Non-limiting examples of general classes of vectors include viral vectors, plasmid vectors, phage vectors, phagemid vectors, cosmid vectors, fosmid vectors, bacteriophages, artificial chromosomes, minicircles, or Agrobacterium binary vectors in double or single stranded linear or circular form which may or may not be self transmissible or mobilizable. In some embodiments, a viral vector can include, but is not limited, to a retroviral, lentiviral, adenoviral, adeno-associated, or herpes simplex viral vector. A vector as defined herein can transform a prokaryotic or eukaryotic host either by integration into the cellular genome or exist extrachromosomally (e.g., autonomous replicating plasmid with an origin of replication). Additionally included are shuttle vectors by which is meant a DNA vehicle capable, naturally or by design, of replication in two different host organisms, which may be selected from actinomycetes and related species, bacteria and eukaryotic (e.g. higher plant, mammalian, yeast or fungal cells). In some embodiments, the nucleic acid in the vector is under the control of, and operably linked to, an appropriate promoter or other regulatory elements for transcription in a host cell. The vector may be a bi-functional expression vector which functions in multiple hosts. In the case of genomic DNA, this may contain its own promoter and/or other regulatory elements and in the case of cDNA this may be under the control of an appropriate promoter and/or other regulatory elements for expression in the host cell. Accordingly, a nucleic acid construct of this invention and/or expression cassettes comprising the same may be comprised in vectors as described herein and as known in the art.
As used herein, “contact,” “contacting,” “contacted,” and grammatical variations thereof, refer to placing the components of a desired reaction together under conditions suitable for carrying out the desired reaction (e.g., transformation, transcriptional control, genome editing, nicking, and/or cleavage). Thus, for example, a target nucleic acid may be contacted with a nucleic acid construct of the invention encoding, for example, a nucleic acid binding polypeptide (e.g., a DNA binding domain such as a sequence-specific DNA binding protein (e.g., a polynucleotide-guided endonuclease, a CRISPR-Cas effector protein (e.g., CRISPR-Cas endonuclease), a zinc finger effector protein, meganuclease, and/or a transcription activator-like effector (TALE) protein (e.g., a TALE nuclease (TALEN), and/or an Argonaute protein), a guide nucleic acid, and optionally a cytosine deaminase and/or adenine deaminase, under conditions whereby the nucleic acid binding polypeptide (e.g., a CRISPR-Cas effector protein) is expressed, and the nucleic acid binding domain forms a complex with the guide nucleic acid, the complex hybridizes to the target nucleic acid, and optionally the cytosine deaminase and/or adenine deaminase is/are recruited to the nucleic acid binding domain (and thus, to the target nucleic acid) or the cytosine deaminase and/or adenine deaminase are fused to the nucleic acid binding domain, thereby modifying the target nucleic acid. In some embodiments, the cytosine deaminase and/or adenine deaminase and the nucleic acid binding domain localize at the target nucleic acid, optionally through covalent and/or non-covalent interactions.
In some embodiments, a target nucleic acid may be contacted with a nucleic acid construct of the invention encoding an engineered protein of the present invention, a guide nucleic acid, and optionally a cytosine deaminase and/or adenine deaminase under conditions whereby the engineered protein is expressed, or a target nucleic acid may be contacted with an engineered protein of the present invention, a guide nucleic acid, and optionally a cytosine deaminase and/or adenine deaminase. The engineered protein can form a complex with the guide nucleic acid, and the complex can hybridize to the target nucleic acid, and optionally the cytosine deaminase and/or adenine deaminase is/are recruited to the engineered protein (and thus, to the target nucleic acid) or the cytosine deaminase and/or adenine deaminase are fused to the engineered protein, thereby modifying the target nucleic acid. The cytosine deaminase and/or adenine deaminase and the engineered protein may localize at the target nucleic acid, optionally through covalent and/or non-covalent interactions.
As used herein, “modifying” or “modification” in reference to a target nucleic acid and/or target sequence includes editing (e.g., mutating), covalent modification, exchanging/substituting nucleic acids/nucleotide bases, deleting, cleaving, and/or nicking of a target nucleic acid and/or target sequence to thereby provide a modified nucleic acid and/or altering transcriptional control of a target nucleic acid and/or target sequence to thereby provide a modified nucleic acid. In some embodiments, a modification may include an insertion and/or deletion of any size and/or a single base change (SNP) of any type. In some embodiments, a modification comprises a SNP. In some embodiments, a modification comprises exchanging and/or substituting one or more (e.g., 1, 2, 3, 4, 5, or more) nucleotides. In some embodiments, an insertion or deletion may be about 1 base to about 30,000 bases in length or more (e.g., about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, 700, 710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, 10,000, 10,500, 11,000, 11,500, 12,000, 12,500, 13,000, 13,500, 14,000, 14,500, 15,000, 15,500, 16,000, 16,500, 17,000, 17,500, 18,000, 18,500, 19,000, 19,500, 20,000, 20,500, 21,000, 21,500, 22,000, 22,500, 23,000, 23,500, 24,000, 24,500, 25,000, 25,500, 26,000, 26,500, 27,000, 27,500, 28,000, 28,500, 29,000, 29,500, 30,000 bases in length or more, or any value or range therein). Thus, in some embodiments, an insertion or deletion may be about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300 to about 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, 700, 710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000 bases in length, or any range or value therein; about 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300 bases to about 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, 700, 710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000 bases or more in length, or any value or range therein; about 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, 700, 710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000 bases to about 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, or 10,000 bases or more in length, or any value or range therein; or about 400, 410, 420, 430, 440, 450, 460, 470, 480, 490, 500, 510, 520, 530, 540, 550, 560, 570, 580, 590, 600, 610, 620, 630, 640, 650, 660, 670, 680, 690, or 700 bases to about 710, 720, 730, 740, 750, 760, 770, 780, 790, 800, 810, 820, 830, 840, 850, 860, 870, 880, 890, 900, 910, 920, 930, 940, 950, 960, 970, 980, 990, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2500, 3000, 3500, 4000, 4500, or 5000 bases or more in length, or any value or range therein. In some embodiments, an insertion or deletion may be about 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800, 1900, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, or 10,000 bases to about 10,500, 11,000, 11,500, 12,000, 12,500, 13,000, 13,500, 14,000, 14,500, 15,000, 15,500, 16,000, 16,500, 17,000, 17,500, 18,000, 18,500, 19,000, 19,500, 20,000, 20,500, 21,000, 21,500, 22,000, 22,500, 23,000, 23,500, 24,000, 24,500, 25,000, 25,500, 26,000, 26,500, 27,000, 27,500, 28,000, 28,500, 29,000, 29,500, or 30,000 bases or more in length, or any value or range therein.
In some embodiments, a nucleic acid construct of the invention (e.g., a polynucleotide encoding a CRISPR-Cas effector protein, a polynucleotide encoding a fusion protein of the present invention, and/or a guide nucleic acid and/or expression cassettes and/or vectors comprising the same) may be operably linked to at least one regulatory sequence, optionally, wherein the at least one regulatory sequence may be codon optimized for expression in a plant. In some embodiments, the at least one regulatory sequence may be, for example, a promoter, an operon, a terminator, or an enhancer. In some embodiments, the at least one regulatory sequence may be a promoter. In some embodiments, the regulatory sequence may be an intron. In some embodiments, the at least one regulatory sequence may be, for example, a promoter operably associated with an intron or a promoter region comprising an intron. In some embodiments, the at least one regulatory sequence may be, for example a ubiquitin promoter and its associated intron (e.g., Medicago truncatula and/or Zea mays and their associated introns). In some embodiments, the at least one regulatory sequence may be a terminator nucleotide sequence and/or an enhancer nucleotide sequence.
In some embodiments, a nucleic acid construct of the invention may be operably associated with a promoter region, wherein the promoter region comprises an intron, optionally wherein the promoter region may be a ubiquitin promoter and intron (e.g., a Medicago or a maize ubiquitin promoter and intron, e.g., SEQ ID NO:1 or SEQ ID NO:2). In some embodiments, the nucleic acid construct of the invention that is operably associated with a promoter region comprising an intron may be codon optimized for expression in a plant.
In some embodiments, a nucleic acid construct of the invention may encode one or more (e.g., 1, 2, 3, 4, or more) polypeptide(s) of interest, optionally wherein the one or more polypeptides of interest may be codon optimized for expression in a plant. In some embodiments, an engineered protein may comprise to one or more (e.g., 1, 2, 3, 4, or more) polypeptide(s) of interest. For example, the heterologous polypeptide of an engineered protein may comprise or be a polypeptide of interest.
A polypeptide of interest useful with this invention can include, but is not limited to, a polypeptide or protein domain having deaminase activity, nickase activity, recombinase activity, transposase activity, methylase activity, glycosylase (DNA glycosylase) activity, glycosylase inhibitor activity (e.g., uracil-DNA glycosylase inhibitor (UGI)), a reverse transcriptase, a peptide tag (e.g., a GCN4 peptide tag), demethylase activity, transcription activation activity, transcription repression activity, transcription release factor activity, histone modification activity, nuclease activity, single-strand RNA cleavage activity, double-strand RNA cleavage activity, restriction endonuclease activity (e.g., Fok1), nucleic acid binding activity, methyltransferase activity, DNA repair activity, DNA damage activity, dismutase activity, alkylation activity, depurination activity, oxidation activity, pyrimidine dimer forming activity, integrase activity, transposase activity, polymerase activity, ligase activity, helicase activity, a nuclear localization sequence or activity, an affinity polypeptide, a peptide tag, and/or photolyase activity. In some embodiments, the polypeptide of interest is a Fok1 nuclease, or a uracil-DNA glycosylase inhibitor. When encoded in a nucleic acid (polynucleotide, expression cassette, and/or vector) the encoded polypeptide or protein domain may be codon optimized for expression in an organism. In some embodiments, a polypeptide of interest may be linked to an engineered protein of the present invention or CRISPR-Cas effector protein domain to provide a CRISPR-Cas fusion protein. In some embodiments, a CRISPR-Cas fusion protein that comprises a CRISPR-Cas effector protein domain linked to a peptide tag may also be linked to a polypeptide of interest (e.g., a CRISPR-Cas effector protein domain may be, for example, linked to both a peptide tag (or an affinity polypeptide) and, for example, a polypeptide of interest.
In some embodiments, an editing system of the present invention comprises a CRISPR-Cas effector protein. As used herein, a “CRISPR-Cas effector protein” is a protein or polypeptide or domain thereof that cleaves, cuts, or nicks a nucleic acid; binds a nucleic acid (e.g., a target nucleic acid and/or a guide nucleic acid); and/or that identifies, recognizes, or binds a guide nucleic acid as defined herein. In some embodiments, a CRISPR-Cas effector protein may be an enzyme (e.g., a nuclease, endonuclease, nickase, etc.) or a portion thereof and/or may function as an enzyme. In some embodiments, a CRISPR-Cas effector protein refers to a CRISPR-Cas nuclease polypeptide or domain thereof. In some embodiments, a CRISPR-Cas effector protein comprises nuclease activity and/or nickase activity, comprises a nuclease domain whose nuclease activity and/or nickase activity has been reduced or eliminated, and/or comprises single stranded DNA cleavage activity (ss DNAse activity) or which has ss DNAse activity that has been reduced or eliminated, and/or comprises self-processing RNAse activity or which has self-processing RNAse activity that has been reduced or eliminated. A CRISPR-Cas effector protein may bind to a target nucleic acid and/or to a target sequence. A CRISPR-Cas effector protein may be a Type I, II, III, IV, V, or VI CRISPR-Cas effector protein. In some embodiments, a CRISPR-Cas effector protein may be from a Type I CRISPR-Cas system, a Type II CRISPR-Cas system, a Type III CRISPR-Cas system, a Type IV CRISPR-Cas system, Type V CRISPR-Cas system, or a Type VI CRISPR-Cas system. In some embodiments, a CRISPR-Cas effector protein of the invention may be from a Type II CRISPR-Cas system or a Type V CRISPR-Cas system. In some embodiments, a CRISPR-Cas effector protein may be a Type II CRISPR-Cas effector protein, for example, a Cas9 effector protein. In some embodiments, a CRISPR-Cas effector protein may be Type V CRISPR-Cas effector protein, for example, a Cas12 effector protein. In some embodiments, a CRISPR-Cas effector protein may be devoid of a nuclear localization signal (NLS). In some embodiments, a CRISPR-Cas effector protein may be Cas12a and optionally may have an amino acid sequence of any one of SEQ ID NOs:16-32 or 70-72 and/or a nucleotide sequence of any one of SEQ ID NOs:33-35. In some embodiments, a CRISPR-Cas effector protein may be an active Cas12a and optionally may have an amino acid sequence of SEQ ID NO:24. In some embodiments, a CRISPR-Cas effector protein may be an inactive (i.e., dead) Cas12a and optionally may have an amino acid sequence of SEQ ID NO:16 or 72. In some embodiments, a CRISPR-Cas effector protein may be Cas12b and optionally may have an amino acid sequence of SEQ ID NO:80 or 81. In some embodiments, a CRISPR-Cas effector protein may be a Cas12a and optionally may have an amino acid sequence of SEQ ID NO:70 or 71. In some embodiments, a CRISPR-Cas effector protein may be a Cas12b and optionally may have an amino acid sequence of SEQ ID NO:81. In some embodiments, a CRISPR-Cas effector protein may be a Cas12f and optionally may have an amino acid sequence of SEQ ID NO:82. In some embodiments, a CRISPR-Cas effector protein may be a Cas12i and optionally may have an amino acid sequence of SEQ ID NO:83.
Exemplary CRISPR-Cas effector proteins may be or include, but are not limited to, a Cas9, C2c1, C2c3, Cas12a (also referred to as Cpf1), Cas12b, Cas12c, Cas12d, Cas12e, Cas13a, Cas13b, Cas13c, Cas13d, Cas1, Cas1B, Cas2, Cas3, Cas3′, Cas3″, Cas4, Cas5, Cas6, Cas7, Cas8, Cas9 (also known as Csn1 and Csx12), Cas10, Csy1, Csy2, Csy3, Cse1, Cse2, Csc1, Csc2, Csa5, Csn2, Csm2, Csm3, Csm4, Csm5, Csm6, Cmr1, Cmr3, Cmr4, Cmr5, Cmr6, Csb1, Csb2, Csb3, Csx17, Csx14, Csx10, Csx16, CsaX, Csx3, Csx1, Csx15, Csf1, Csf2, Csf3, Csf4 (dinG), and/or Csf5 nuclease, optionally wherein the CRISPR-Cas effector protein may be a Cas9, Cas12a (Cpf1), Cas12b, Cas12c (C2c3), Cas12d (CasY), Cas12e (CasX), Cas12g, Cas12h, Cas12i, C2c4, C2c5, C2c8, C2c9, C2c10, Cas14a, Cas14b, and/or Cas14c effector protein.
In some embodiments, a CRISPR-Cas effector protein useful with the invention may comprise a mutation in its nuclease active site and/or nuclease domain (e.g., a RuvC, HNH, e.g., a RuvC site of a Cas12a nuclease domain; e.g., RuvC site and/or HNH site of a Cas9 nuclease domain). A CRISPR-Cas effector protein having a mutation in its nuclease active site and/or nuclease domain, and therefore, no longer comprising nuclease activity, is commonly referred to as “inactive” or “dead,” e.g., dCas9. In some embodiments, a CRISPR-Cas effector protein domain or polypeptide having a mutation in its nuclease active site and/or nuclease domain may have impaired activity or reduced activity (e.g., nickase activity) as compared to the same CRISPR-Cas effector protein without the mutation.
A CRISPR Cas9 effector protein or Cas9 useful with this invention may be any known or later identified Cas9 nuclease. In some embodiments, a Cas9 can be a protein from, for example, Streptococcus spp. (e.g., S. pyogenes, S. thermophiles), Lactobacillus spp., Bifidobacterium spp., Kandleria spp., Leuconostoc spp., Oenococcus spp., Pediococcus spp., Weissella spp., and/or Olsenella spp. In some embodiments, a CRISPR-Cas effector protein may be a Cas9 polypeptide or domain thereof and optionally may have a nucleotide sequence of any one of SEQ ID NOs:3-13 or SEQ ID NOs:53-56 and/or an amino acid sequence of any one of SEQ ID NOs:14-15.
In some embodiments, the CRISPR-Cas effector protein may be a Cas9 polypeptide derived from Streptococcus pyogenes and/or may recognize the PAM sequence motif NGG, NAG, NGA (Mali et al, Science 2013; 339(6121): 823-826). In some embodiments, the CRISPR-Cas effector protein may be a Cas9 polypeptide derived from Streptococcus thermophiles and/or may recognize the PAM sequence motif NGGNG and/or NNAGAAW (W =A or T) (See, e.g., Horvath et al, Science, 2010; 327(5962): 167-170, and Deveau et al, J Bacteriol 2008; 190(4): 1390-1400). In some embodiments, the CRISPR-Cas effector protein may be a Cas9 polypeptide derived from Streptococcus mutans and/or may recognize the PAM sequence motif NGG and/or NAAR (R=A or G) (See, e.g., Deveau et al, J BACTERIOL 2008; 190(4): 1390-1400). In some embodiments, the CRISPR-Cas effector protein may be a Cas9 polypeptide derived from Streptococcus aureus and/or may recognize the PAM sequence motif NNGRR (R=A or G). In some embodiments, the CRISPR-Cas effector protein may be a Cas9 protein derived from S. aureus and/or may recognize the PAM sequence motif N GRRT (R=A or G). In some embodiments, the CRISPR-Cas effector protein may be a Cas9 polypeptide derived from S. aureus and/or may recognize the PAM sequence motif N GRRV (R=A or G). In some embodiments, the CRISPR-Cas effector protein may be a Cas9 polypeptide that is derived from Neisseria meningitidis and/or may recognize the PAM sequence motif N GATT or N GCTT (R=A or G, V=A, G or C) (See, e.g., Hou et ah, PNAS 2013, 1-6). In the aforementioned embodiments, in this paragraph, N in the PAM sequence motif can be any nucleotide residue, e.g., any of A, G, C or T. In some embodiments, the CRISPR-Cas effector protein may be a Cas13a protein derived from Leptotrichia shahii and/or may recognize a protospacer flanking sequence (PFS) (or RNA PAM (rPAM)) sequence motif of a single 3′ A, U, or C, which may be located within the target nucleic acid and/or target sequence.
A Type V CRISPR-Cas effector protein useful with embodiments of the invention may be any Type V CRISPR-Cas nuclease. Exemplary Type V CRISPR-Cas proteins include, but are not limited to, Cas12a (Cpf1), Cas12b, Cas12c (C2c3), Cas12d (CasY), Cas12e (CasX), Cas12g, Cas12h, Cas12i, C2c1, C2c4, C2c5, C2c8, C2c9, C2c10, Cas14a, Cas14b, and/or Cas14c nuclease. In some embodiments, a Type V CRISPR-Cas nuclease polypeptide or domain useful with embodiments of the invention may be a Cas12a polypeptide or domain. In some embodiments, a Type V CRISPR-Cas effector protein may be a nickase, optionally, a Cas12a nickase. In some embodiments, a CRISPR-Cas effector protein may be a Cas12a polypeptide or domain thereof and optionally may have an amino acid sequence of any one of SEQ ID NOs:16-32 and/or a nucleotide sequence of any one of SEQ ID NOs:33-35.
In some embodiments, the CRISPR-Cas effector protein may be a Type V Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas nuclease. Cas12a differs in several respects from the more well-known Type II CRISPR Cas9 nuclease. For example, Cas9 recognizes a G-rich protospacer-adjacent motif (PAM) that is 3′ to its guide RNA (gRNA, sgRNA, crRNA, crDNA, CRISPR array) binding site (protospacer, target nucleic acid, target DNA) (3′-NGG), while Cas12a recognizes a T-rich PAM that is located 5′ to the target nucleic acid (5′-TTN, 5′-TTTN. In fact, the orientations in which Cas9 and Cas12a bind their guide RNAs are very nearly reversed in relation to their N and C termini. Furthermore, Cas12a enzymes use a single guide RNA (gRNA, CRISPR array, crRNA) rather than the dual guide RNA (sgRNA (e.g., crRNA and tracrRNA)) found in natural Cas9 systems, and Cas12a processes its own gRNAs. Additionally, Cas12a nuclease activity produces staggered DNA double stranded breaks instead of blunt ends produced by Cas9 nuclease activity, and Cas12a relies on a single RuvC domain to cleave both DNA strands, whereas Cas9 utilizes an HNH domain and a RuvC domain for cleavage.
A CRISPR Cas12a effector protein useful with this invention may be any known or later identified Cas12a polypeptide (previously known as Cpf1) (see, e.g., U.S. Pat. No. 9,790,490, which is incorporated by reference for its disclosures of Cpf1 (Cas12a) sequences). The term “Cas12a” refers to an RNA-guided protein that can have nuclease activity, the protein comprising a guide nucleic acid binding domain and/or an active, inactive, or partially active DNA cleavage domain, thereby the RNA-guided nuclease activity of the Cas12a may be active, inactive or partially active, respectively. In some embodiments, a Cas12a useful with the invention may comprise a mutation in the nuclease active site (e.g., RuvC site of the Cas12a domain). A Cas12a having a mutation in its nuclease domain and/or nuclease active site, and therefore, no longer comprising nuclease activity, is commonly referred to as deadCas12a (e.g., dCas12a). In some embodiments, a Cas12a having a mutation in its nuclease domain and/or nuclease active site may have impaired activity, e.g., may have reduced nickase activity.
In some embodiments, a CRISPR-Cas effector protein may be optimized for expression in an organism, for example, in an animal (e.g., a mammal such as a human), a plant, a fungus, an archaeon, or a bacterium. In some embodiments, a CRISPR-Cas effector protein (e.g., Cas12a polypeptide/domain or a Cas9 polypeptide/domain) may be optimized for expression in a plant and/or for expression in an Agrobacterium strain.
A “guide nucleic acid,” “guide RNA,” “gRNA,” “CRISPR RNA/DNA,” “CRISPR guide nucleic acid,” “crRNA” or “crDNA” as used herein means a nucleic acid that comprises at least one spacer sequence, which is complementary to (and hybridizes to) a target DNA (e.g., protospacer), and at least one repeat sequence (e.g., a repeat of a Type V Cas12a CRISPR-Cas system, or a fragment or portion thereof; a repeat of a Type II Cas9 CRISPR-Cas system, or fragment thereof; a repeat of a Type V C2c1 CRISPR Cas system, or a fragment thereof; a repeat of a CRISPR-Cas system of, for example, C2c3, Cas12a (also referred to as Cpf1), Cas12b, Cas12c, Cas12d, Cas12e, Cas12f, Cas12i, Cas13a, Cas13b, Cas13c, Cas13d, Cas1, Cas1B, Cas2, Cas3, Cas3′, Cas3″, Cas4, Cas5, Cas6, Cas7, Cas8, Cas9 (also known as Csn1 and Csx12), Cas10, Csy1, Csy2, Csy3, Cse1, Cse2, Csc1, Csc2, Csa5, Csn2, Csm2, Csm3, Csm4, Csm5, Csm6, Cmr1, Cmr3, Cmr4, Cmr5, Cmr6, Csb1, Csb2, Csb3, Csx17, Csx14, Csx1 0, Csx16, CsaX, Csx3, Csx1, Csx15, Csf1, Csf2, Csf3, Csf4 (dinG), and/or Csf5, or a fragment thereof), wherein the repeat sequence may be linked to the 5′ end and/or the 3′ end of the spacer sequence. In some embodiments, the guide nucleic acid comprises DNA. In some embodiments, the guide nucleic acid comprises RNA. The design of a gRNA of this invention may be based on a Type I, Type II, Type III, Type IV, Type V, or Type VI CRISPR-Cas system.
In some embodiments, a Cas12a gRNA may comprise, from 5′ to 3′, a repeat sequence (full length or portion thereof (“handle”); e.g., pseudoknot-like structure) and a spacer sequence.
In some embodiments, a guide nucleic acid may comprise more than one repeat sequence-spacer sequence (e.g., 2, 3, 4, 5, 6, 7, 8, 9, 10, or more repeat-spacer sequences) (e.g., repeat-spacer-repeat, e.g., repeat-spacer-repeat-spacer-repeat-spacer-repeat-spacer-repeat-spacer, and the like). The guide nucleic acids of this invention are synthetic, human-made and not found in nature. A gRNA can be quite long and may be used as an aptamer (like in the MS2 recruitment strategy) or other RNA structures hanging off the spacer.
A “repeat sequence” as used herein, refers to, for example, any repeat sequence of a wild-type CRISPR Cas locus (e.g., a Cas9 locus, a Cas12a locus, a C2c1 locus, etc.) or a repeat sequence of a synthetic crRNA that is functional with the CRISPR-Cas effector protein encoded by the nucleic acid constructs of the invention. A repeat sequence useful with this invention can be any known or later identified repeat sequence of a CRISPR-Cas locus (e.g., Type I, Type II, Type III, Type IV, Type V or Type VI) or it can be a synthetic repeat designed to function in a Type I, II, III, IV, V or VI CRISPR-Cas system. A repeat sequence may comprise a hairpin structure and/or a stem loop structure. In some embodiments, a repeat sequence may form a pseudoknot-like structure at its 5′ end (i.e., “handle”). Thus, in some embodiments, a repeat sequence can be identical to or substantially identical to a repeat sequence from wild-type Type I CRISPR-Cas loci, Type II, CRISPR-Cas loci, Type III, CRISPR-Cas loci, Type IV CRISPR-Cas loci, Type V CRISPR-Cas loci and/or Type VI CRISPR-Cas loci. A repeat sequence from a wild-type CRISPR-Cas locus may be determined through established algorithms, such as using the CRISPRfinder offered through CRISPRdb (see, Grissa et al. Nucleic Acids Res. 35(Web Server issue):W52-7). In some embodiments, a repeat sequence or portion thereof is linked at its 3′ end to the 5′ end of a spacer sequence, thereby forming a repeat-spacer sequence (e.g., guide nucleic acid, guide RNA/DNA, crRNA, crDNA).
In some embodiments, a repeat sequence comprises, consists essentially of, or consists of at least 10 nucleotides depending on the particular repeat and whether the guide nucleic acid comprising the repeat is processed or unprocessed (e.g., about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 to 100 or more nucleotides, or any range or value therein; e.g., about). In some embodiments, a repeat sequence comprises, consists essentially of, or consists of about 10 to about 20, about 10 to about 30, about 10 to about 45, about 10 to about 50, about 15 to about 30, about 15 to about 40, about 15 to about 45, about 15 to about 50, about 20 to about 30, about 20 to about 40, about 20 to about 50, about 30 to about 40, about 40 to about 80, about 50 to about 100 or more nucleotides.
A repeat sequence linked to the 5′ end of a spacer sequence can comprise a portion of a repeat sequence (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35 or more contiguous nucleotides of a wild-type repeat sequence). In some embodiments, a portion of a repeat sequence linked to the 5′ end of a spacer sequence can be about five to about ten consecutive nucleotides in length (e.g., about 5, 6, 7, 8, 9, 10 nucleotides) and have at least 90% sequence identity (e.g., at least about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or more) to the same region (e.g., 5′ end) of a wild-type CRISPR Cas repeat nucleotide sequence. In some embodiments, a portion of a repeat sequence may comprise a pseudoknot-like structure at its 5′ end (e.g., “handle”).
A “spacer sequence” as used herein is a nucleotide sequence that is complementary to a target nucleic acid (e.g., target DNA) (e.g., protospacer) and/or to a target sequence. The spacer sequence can be fully complementary or substantially complementary (e.g., at least about 70% complementary (e.g., about 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or more)) to a target nucleic acid and/or target sequence. Thus, in some embodiments, the spacer sequence can have one, two, three, four, or five mismatches as compared to the target nucleic acid and/or target sequence, which mismatches can be contiguous or noncontiguous. In some embodiments, the spacer sequence can have 70% complementarity to a target nucleic acid and/or target sequence. In other embodiments, the spacer nucleotide sequence can have 80% complementarity to a target nucleic acid and/or target sequence. In still other embodiments, the spacer nucleotide sequence can have 85%, 90%, 95%, 96%, 97%, 98%, 99% or 99.5% complementarity, and the like, to the target nucleic acid (protospacer) and/or target sequence. In some embodiments, the spacer sequence is 100% complementary to the target nucleic acid and/or target sequence. A spacer sequence may have a length from about 15 nucleotides to about 30 nucleotides (e.g., 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 nucleotides, or any range or value therein). Thus, in some embodiments, a spacer sequence may have complete complementarity or substantial complementarity over a region of a target nucleic acid (e.g., protospacer) and/or target sequence that is at least about 15 nucleotides to about 30 nucleotides in length. In some embodiments, the spacer is about 20 nucleotides in length. In some embodiments, the spacer is about 21, 22, or 23 nucleotides in length. In some embodiments, a spacer that is complementary to a target nucleic acid is also complementary to a target sequence that corresponds to the target nucleic acid and/or a spacer for a target nucleic acid is the same as a spacer for a target sequence that corresponds to the target nucleic acid. The description herein for a target nucleic acid (e.g., in regard to a spacer that is complementary to a target nucleic acid, a guide nucleic acid for a target nucleic acid, and/or modifying a target nucleic acid using an editing system and/or nucleic acid binding polypeptide) can equally apply to a target sequence.
In some embodiments, the 5′ region of a spacer sequence of a guide nucleic acid may be fully complementary to a target nucleic acid, while the 3′ region of the spacer may be substantially complementary to the target nucleic acid (such as for a spacer in a Type V CRISPR-Cas system), or the 3′ region of a spacer sequence of a guide nucleic acid may be fully complementary to a target nucleic acid, while the 5′ region of the spacer may be substantially complementary to the target nucleic acid (such as for a spacer in a Type II CRISPR-Cas system), and therefore, the overall complementarity of the spacer sequence to the target nucleic acid may be less than 100%. Thus, for example, in a guide nucleic acid for a Type V CRISPR-Cas system, the first 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 nucleotides in the 5′ region (i.e., seed region) of, for example, a 20 nucleotide spacer sequence may be 100% complementary to the target nucleic acid, while the remaining nucleotides in the 3′ region of the spacer sequence are substantially complementary (e.g., at least about 70% complementary) to the target nucleic acid. In some embodiments, the first 1 to 8 nucleotides (e.g., the first 1, 2, 3, 4, 5, 6, 7, 8, nucleotides, and any range therein) of the 5′ end of the spacer sequence may be 100% complementary to the target nucleic acid, while the remaining nucleotides in the 3′ region of the spacer sequence are substantially complementary (e.g., at least about 50% complementary (e.g., 50%, 55%, 60%, 65%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or more)) to the target nucleic acid.
As a further example, in a guide nucleic acid for a Type II CRISPR-Cas system, the first 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 nucleotides in the 3′ region (i.e., seed region) of, for example, a 20 nucleotide spacer sequence may be 100% complementary to the target nucleic acid, while the remaining nucleotides in the 5′ region of the spacer sequence are substantially complementary (e.g., at least about 70% complementary) to the target nucleic acid. In some embodiments, the first 1 to 10 nucleotides (e.g., the first 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 nucleotides, and any range therein) of the 3′ end of the spacer sequence may be 100% complementary to the target nucleic acid, while the remaining nucleotides in the 5′ region of the spacer sequence are substantially complementary (e.g., at least about 50% complementary (e.g., at least about 50%, 55%, 60%, 65%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or more or any range or value therein)) to the target nucleic acid.
In some embodiments, a seed region of a spacer may be about 8 to about 10 nucleotides in length, about 5 to about 6 nucleotides in length, or about 6 nucleotides in length.
As used herein, a “target nucleic acid”, “target DNA,” “target nucleotide sequence,” “target region,” and “target region in the genome” are used interchangeably herein and refer to a region of an organism's (e.g., a plant's) genome that comprises a sequence that is fully complementary (100% complementary) or substantially complementary (e.g., at least 70% complementary (e.g., 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or more)) to a spacer sequence in a guide nucleic acid as defined herein. In some embodiments, a target nucleic acid includes a sequence that is fully complementary (100% complementary) or substantially complementary to a spacer sequence in a guide nucleic acid and includes about 0 to about 100 consecutive nucleotides upstream of the sequence that is fully or substantially complementary to the spacer sequence and/or about 0 to about 100 consecutive nucleotides downstream of the sequence that is fully or substantially complementary to the spacer sequence. A target nucleic acid is targeted by an editing system (or a component thereof) as described herein. A target region useful for a CRISPR-Cas system may be located immediately 3′ (e.g., Type V CRISPR-Cas system) or immediately 5′ (e.g., Type II CRISPR-Cas system) to a PAM sequence in the genome of the organism (e.g., a plant genome or mammalian (e.g., human) genome). A target region may be selected from any region of at least 15 consecutive nucleotides (e.g., 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30 nucleotides, and the like) located immediately adjacent to a PAM sequence.
A “protospacer sequence” or “protospacer” as used herein refer to a sequence that is fully or substantially complementary to (and can hybridize to) a spacer sequence of a guide nucleic acid. In some embodiments, the protospacer is all or a portion of a target nucleic acid as defined herein that is fully or substantially complementary (and hybridizes) to the spacer sequence of the CRISPR repeat-spacer sequences (e.g., guide nucleic acids, CRISPR arrays, crRNAs).
In the case of Type V CRISPR-Cas (e.g., Cas12a) systems and Type II CRISPR-Cas (Cas9) systems, the protospacer sequence is flanked by (e.g., immediately adjacent to) a protospacer adjacent motif (PAM). For Type IV CRISPR-Cas systems, the PAM is located at the 5′ end on the non-target strand and at the 3′ end of the target strand (see below, as an example).
In the case of Type II CRISPR-Cas (e.g., Cas9) systems, the PAM is located immediately 3′ of the target region. The PAM for Type I CRISPR-Cas systems is located 5′ of the target strand. There is no known PAM for Type III CRISPR-Cas systems. Makarova et al. describes the nomenclature for all the classes, types and subtypes of CRISPR systems (Nature Reviews Microbiology 13:722-736 (2015)). Guide structures and PAMs are described in by R. Barrangou (Genome Biol. 16:247 (2015)).
Canonical Cas12a PAMs are T rich. In some embodiments, a canonical Cas12a PAM sequence may be 5′-TTN, 5′-TTTN, or 5′-TTTV. In some embodiments, canonical Cas9 (e.g., S. pyogenes) PAMs may be 5′-NGG-3′. In some embodiments, non-canonical PAMs may be used but may be less efficient.
Additional PAM sequences may be determined by those skilled in the art through established experimental and computational approaches. Thus, for example, experimental approaches include targeting a sequence flanked by all possible nucleotide sequences and identifying sequence members that do not undergo targeting, such as through the transformation of target plasmid DNA (Esvelt et al. 2013. Nat. Methods 10:1116-1121; Jiang et al. 2013. Nat. Biotechnol. 31:233-239). In some aspects, a computational approach can include performing BLAST searches of natural spacers to identify the original target DNA sequences in bacteriophages or plasmids and aligning these sequences to determine conserved sequences adjacent to the target sequence (Briner and Barrangou. 2014. Appl. Environ. Microbiol. 80:994-1001; Mojica et al. 2009. Microbiology 155:733-740).
“Recruit,” “recruiting” or “recruitment” as used herein refer to attracting one or more polypeptide(s) or polynucleotide(s) to another polypeptide or polynucleotide (e.g., to a particular location in a genome) using protein-protein interactions, nucleic acid-protein interactions (e.g., RNA-protein interactions), and/or chemical interactions. Protein-protein interactions can include, but are not limited to, peptide tags (epitopes, multimerized epitopes) and corresponding affinity polypeptides, RNA recruiting motifs and corresponding affinity polypeptides, and/or chemical interactions. Example chemical interactions that may be useful with polypeptides and polynucleotides for the purpose of recruitment can include, but are not limited to, rapamycin-inducible dimerization of FRB-FKBP; Biotin-streptavidin interaction; SNAP tag (Hussain et al. Curr Pharm Des. 19(30):5437-42 (2013)); Halo tag (Los et al. ACS Chem Biol. 3(6):373-82 (2008)); CLIP tag (Gautier et al. Chemistry & Biology 15:128-136 (2008)); DmrA-DmrC heterodimer induced by a compound (Tak et al. Nat Methods 14(12):1163-1166 (2017)); Bifunctional ligand approaches (fuse two protein-binding chemicals together) (Voβ et al. Curr Opin Chemical Biology 28:194-201 (2015)) (e.g. dihyrofolate reductase (DHFR) (Kopyteck et al. Cell Cehm Biol 7(5):313-321 (2000)).
A “recruiting motif” as used herein refers to one half of a binding pair that may be used to recruit a compound to which the recruiting motif is bound to another compound that includes the other half of the binding pair (i.e., a “corresponding motif”). The recruiting motif and corresponding motif may bind covalently and/or noncovalently. In some embodiments, a recruiting motif is an RNA recruiting motif (e.g., an RNA recruiting motif that is capable of binding and/or configured to bind to an affinity polypeptide), an affinity polypeptide (e.g., an affinity polypeptide that is capable of binding and/or configured to bind an RNA recruiting motif and/or a peptide tag), or a peptide tag (e.g., a peptide tag that is capable of binding and/or configured to bind an affinity polypeptide). For example, when a recruiting motif is an RNA recruiting motif, the corresponding motif for the RNA recruiting motif may be an affinity polypeptide that binds the RNA recruiting motif. A further example is that when a recruiting motif is a peptide tag, the corresponding motif for the peptide tag may be an affinity polypeptide that binds the peptide tag. Thus, a compound comprising a recruiting motif (e.g., an affinity polypeptide) may be recruited to another compound (e.g., a guide nucleic acid) comprising a corresponding motif for the recruiting motif (e.g., an RNA recruiting motif).
As described herein, a “peptide tag” may be employed to recruit one or more polypeptides. A peptide tag may be any polypeptide that is capable of being bound by a corresponding motif such as an affinity polypeptide. A peptide tag may also be referred to as an “epitope” and when provided in multiple copies, a “multimerized epitope.” Example peptide tags can include, but are not limited to, a GCN4 peptide tag (e.g., Sun-Tag), a c-Myc affinity tag, an HA affinity tag, a His affinity tag, an S affinity tag, a methionine-His affinity tag, an RGD-His affinity tag, a FLAG octapeptide, a strep tag or strep tag II, a V5 tag, and/or a VSV-G epitope. In some embodiments, a peptide tag may also include phosphorylated tyrosines in specific sequence contexts recognized by SH2 domains, characteristic consensus sequences containing phosphoserines recognized by 14-3-3 proteins, proline rich peptide motifs recognized by SH3 domains, PDZ protein interaction domains or the PDZ signal sequences, and an AGO hook motif from plants. Peptide tags are disclosed in WO2018/136783 and U.S. Patent Application Publication No. 2017/0219596, which are incorporated by reference for their disclosures of peptide tags. Peptide tags that may be useful with this invention can include, but are not limited to, SEQ ID NO:39 and SEQ ID NO:40. An affinity polypeptide useful with peptide tags includes, but is not limited to, SEQ ID NO:41.
Any epitope that may be linked to a polypeptide and for which there is a corresponding affinity polypeptide that may be linked to another polypeptide may be used with this invention as a peptide tag. In some embodiments, a peptide tag may comprise 1 or 2 or more copies of a peptide tag (e.g., repeat unit, multimerized epitope (e.g., tandem repeats)) (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or more repeat units. In some embodiments, an affinity polypeptide that interacts with/binds to a peptide tag may be an antibody. In some embodiments, the antibody may be a scFv antibody. In some embodiments, an affinity polypeptide that binds to a peptide tag may be synthetic (e.g., evolved for affinity interaction) including, but not limited to, an affibody, an anticalin, a monobody and/or a DARPin (see, e.g., Sha et al., Protein Sci. 26(5):910-924 (2017)); Gilbreth (Curr Opin Struc Biol 22(4):413-420 (2013)), U.S. Pat. No. 9,982,053, each of which are incorporated by reference in their entireties for the teachings relevant to affibodies, anticalins, monobodies and/or DARPins.
In some embodiments, a guide nucleic acid that is linked to an RNA recruiting motif is provided and a polypeptide comprising an RNA binding polypeptide that binds to the RNA recruiting motif is provided, wherein the guide nucleic acid binds to a target nucleic acid and the RNA recruiting motif binds to the RNA binding polypeptide, which may recruit the polypeptide to the guide nucleic acid and/or vice versa and/or may optionally contact the target nucleic acid with the polypeptide. An RNA recruiting motif may be referred to herein as an RNA motif, and an RNA binding polypeptide may be referred to herein as an affinity polypeptide. In some embodiments, two or more polypeptides may be recruited to a guide nucleic acid, thereby contacting the target nucleic acid with two or more polypeptides.
In some embodiments of the invention, a guide RNA may be linked to one or to two or more RNA recruiting motifs (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or more motifs; e.g., at least 10 to about 25 motifs), optionally wherein the two or more RNA recruiting motifs (i.e., RNA motifs) may be the same RNA recruiting motif or different RNA recruiting motifs. In some embodiments, an RNA recruiting motif and a corresponding motif (i.e., a RNA binding polypeptide such as a corresponding affinity polypeptide) may include, but is not limited, to a telomerase Ku binding motif (e.g., Ku binding hairpin) and an affinity polypeptide of Ku (e.g., Ku heterodimer), a telomerase Sm7 binding motif and an affinity polypeptide of Sm7, an MS2 phage operator stem-loop and an affinity polypeptide of MS2 Coat Protein (MCP), a PP7 phage operator stem-loop and an affinity polypeptide of PP7 Coat Protein (PCP), an SfMu phage Com stem-loop and an affinity polypeptide of Com RNA binding protein, a PUF binding site (PBS) and an affinity polypeptide of pumilio/fem-3 mRNA binding factor (PUF), and/or a synthetic RNA-aptamer and the aptamer ligand as the corresponding affinity polypeptide. In some embodiments, the RNA recruiting motif and corresponding affinity polypeptide may be an MS2 phage operator stem-loop and the affinity polypeptide MS2 Coat Protein (MCP). In some embodiments, the RNA recruiting motif and corresponding affinity polypeptide may be a PUF binding site (PBS) and the affinity polypeptide pumilio/fem-3 mRNA binding factor (PUF). Exemplary RNA motifs or RNA binding polypeptides that may be useful with this invention can include, but are not limited to, SEQ ID NOs:42-52, 57, and 58.
In some embodiments, the components for recruiting polypeptides and nucleic acids may include those that function through chemical interactions that may include, but are not limited to, rapamycin-inducible dimerization of FRB-FKBP; Biotin-streptavidin; SNAP tag; Halo tag; CLIP tag; DmrA-DmrC heterodimer induced by a compound; bifunctional ligand (e.g., fusion of two protein-binding chemicals together; e.g. dihyrofolate reductase (DHFR)).
A peptide tag may comprise or be present in one copy or in 2 or more copies of the peptide tag (e.g., multimerized peptide tag or multimerized epitope) (e.g., about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 9, 20, 21, 22, 23, 24, or 25 or more peptide tags). When multimerized, the peptide tags may be fused directly to one another or they may be linked to one another via one or more amino acids (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 or more amino acids, optionally about 3 to about 10, about 4 to about 10, about 5 to about 10, about 5 to about 15, or about 5 to about 20 amino acids, and the like, and any value or range therein. Thus, in some embodiments, a CRISPR-Cas effector protein of the invention may comprise a CRISPR-Cas effector protein fused to one peptide tag or to two or more peptide tags, optionally wherein the two or more peptide tags are fused to one another via one or more amino acid residues. In some embodiments, a peptide tag useful with the invention may be a single copy of a GCN4 peptide tag or epitope or may be a multimerized GCN4 epitope comprising about 2 to about 25 or more copies of the peptide tag (e.g., about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 or more copies of a GCN4 epitope or any range therein).
In some embodiments, a peptide tag may be fused to a polypeptide (e.g., a CRISPR-Cas effector protein or bacterial transfer protein). In some embodiments, a peptide tag may be fused or linked to the C-terminus of a polypeptide (e.g., a CRISPR-Cas effector protein or bacterial transfer protein) to form a fusion protein. In some embodiments, a peptide tag may be fused or linked to the N-terminus of a polypeptide (e.g., a CRISPR-Cas effector protein or bacterial transfer protein) to form a fusion protein. In some embodiments, a peptide tag may be fused within a polypeptide (e.g., a CRISPR-Cas effector protein or bacterial transfer protein); for example, a peptide tag may be in a loop region of a CRISPR-Cas effector protein.
In some embodiments, when a peptide tag comprises more than one peptide tag, the quantity and spacing of each peptide tag may be optimized to maximize occupation of the peptide tags and minimize steric interference of, for example, deaminase domains, with each other.
An “affinity polypeptide” (e.g., “recruiting polypeptide”) refers to any polypeptide that is capable of binding to its corresponding peptide tag, peptide tag, or RNA motif. An affinity polypeptide for a peptide tag may be, for example, an antibody and/or a single chain antibody that specifically binds the peptide tag, respectively. In some embodiments, an antibody for a peptide tag may be, but is not limited to, an scFv antibody. In some embodiments, an affinity polypeptide may be fused or linked to the N-terminus of a deaminase (e.g., a cytosine deaminase or an adenine deaminase). In some embodiments, the affinity polypeptide is stable under the reducing conditions of a cell or cellular extract.
“Introducing,” “introduce,” “introduced” (and grammatical variations thereof) in the context of a polynucleotide and/or polypeptide means presenting the polynucleotide (e.g., polynucleotide, a nucleic acid construct, and/or a guide nucleic acid) and/or polypeptide to a host organism or cell of said organism (e.g., host cell; e.g., a plant cell) in such a manner that the nucleotide sequence and/or polypeptide gains access to the interior of a cell. Thus, for example, a nucleic acid construct of the invention encoding a nucleic acid binding protein (e.g., a CRISPR-Cas effector protein), a guide nucleic acid, a chimeric protein, and/or a chimeric nucleic acid may be introduced into a cell of an organism, thereby transforming the cell with the nucleic acid binding protein, guide nucleic acid, a chimeric protein, and/or a chimeric nucleic acid. In some embodiments, a polypeptide comprising a nucleic acid binding protein (e.g., a CRISPR-Cas effector protein), a chimeric protein, and/or a chimeric guide nucleic acid may be introduced into a cell of an organism, optionally wherein the nucleic acid binding protein and chimeric guide nucleic acid may be comprised in a complex (e.g., a ribonucleoprotein).
The terms “transformation” or “transfection” may be used interchangeably and as used herein refer to the introduction of a heterologous nucleic acid into a cell. Transformation of a cell may be stable or transient. Thus, in some embodiments, a host cell or host organism may be stably transformed with a polynucleotide/nucleic acid molecule of the invention. In some embodiments, a host cell or host organism may be transiently transformed with a nucleic acid construct of the invention.
“Transient transformation” in the context of a polynucleotide means that a polynucleotide is introduced into the cell and does not integrate into the genome of the cell.
By “stably introducing” or “stably introduced” in the context of a polynucleotide introduced into a cell is intended that the introduced polynucleotide is stably incorporated into the genome of the cell, and thus the cell is stably transformed with the polynucleotide.
“Stable transformation” or “stably transformed” as used herein means that a nucleic acid molecule is introduced into a cell and integrates into the genome of the cell. As such, the integrated nucleic acid molecule is capable of being inherited by the progeny thereof, more particularly, by the progeny of multiple successive generations. “Genome” as used herein includes the nuclear and the plastid genome, and therefore includes integration of the nucleic acid into, for example, the chloroplast or mitochondrial genome. Stable transformation as used herein can also refer to a transgene that is maintained extrachromasomally, for example, as a minichromosome or a plasmid.
Transient transformation may be detected by, for example, an enzyme-linked immunosorbent assay (ELISA) or Western blot, which can detect the presence of a peptide or polypeptide encoded by one or more transgene introduced into an organism. Stable transformation of a cell can be detected by, for example, a Southern blot hybridization assay of genomic DNA of the cell with nucleic acid sequences which specifically hybridize with a nucleotide sequence of a transgene introduced into an organism (e.g., a plant). Stable transformation of a cell can be detected by, for example, a Northern blot hybridization assay of RNA of the cell with nucleic acid sequences which specifically hybridize with a nucleotide sequence of a transgene introduced into a host organism. Stable transformation of a cell can also be detected by, e.g., a polymerase chain reaction (PCR) or other amplification reactions as are well known in the art, employing specific primer sequences that hybridize with target sequence(s) of a transgene, resulting in amplification of the transgene sequence, which can be detected according to standard methods Transformation can also be detected by direct sequencing and/or hybridization protocols well known in the art.
The terms “transgene” or “transgenic” as used herein refer to at least one nucleic acid sequence that is taken from the genome of one organism, or produced synthetically, and which is then introduced into a host cell (e.g., a plant cell) or organism or tissue of interest and which is subsequently integrated into the host's genome by means of “stable” transformation or transfection approaches. In contrast, the term “transient” transformation or transfection or introduction refers to a way of introducing molecular tools including at least one nucleic acid (DNA, RNA, single-stranded or double-stranded or a mixture thereof) and/or at least one amino acid sequence, optionally comprising suitable chemical or biological agents, to achieve a transfer into at least one compartment of interest of a cell, including, but not restricted to, the cytoplasm, an organelle, including the nucleus, a mitochondrion, a vacuole, a chloroplast, or into a membrane, resulting in transcription and/or translation and/or association and/or activity of the at least one molecule introduced without achieving a stable integration or incorporation and thus inheritance of the respective at least one molecule introduced into the genome of a cell. The term “transgene-free” refers to a condition in which a transgene is not present or found in the genome of a host cell or tissue or organism of interest.
Accordingly, in some embodiments, nucleotide sequences, polynucleotides, nucleic acid constructs, and/or expression cassettes of the invention may be expressed transiently and/or they can be stably incorporated into the genome of the host organism. Thus, in some embodiments, a nucleic acid construct of the invention (e.g., one or more expression cassettes encoding a nucleic acid binding protein, an DNA dependent DNA polymerase polypeptide or domain thereof, a domain is capable of interacting with a T-DNA sequence, a T-DNA sequence, and/or nucleic acid modifying polypeptide or domain thereof, and the like) may be transiently introduced into a cell with a guide nucleic acid and as such, no DNA is maintained in the cell.
A nucleic acid construct of the invention may be introduced into a cell (e.g., a plant cell) by any method known to those of skill in the art. In some embodiments, transformation methods include transformation via bacterial-mediated nucleic acid delivery (e.g., via Agrobacteria), viral-mediated nucleic acid delivery, silicon carbide and/or nucleic acid whisker-mediated nucleic acid delivery, liposome mediated nucleic acid delivery, microinjection, microparticle bombardment, calcium-phosphate-mediated transformation, cyclodextrin-mediated transformation, electroporation, nanoparticle-mediated transformation, sonication, infiltration, PEG-mediated nucleic acid uptake, as well as any other electrical, chemical, physical (mechanical) and/or biological mechanism that results in the introduction of nucleic acid into the plant cell, including any combination thereof. In some embodiments of the invention, transformation of a cell comprises nuclear transformation. In some embodiments, transformation of a cell comprises plastid transformation (e.g., chloroplast transformation). In some embodiments, a recombinant nucleic acid construct of the invention can be introduced into a cell via conventional breeding techniques. In some embodiments, one or more of polynucleotide(s), polypeptide(s), expression cassette(s), and/or vector(s) may be introduced into a plant cell via Agrobacterium transformation.
Procedures for transforming both eukaryotic and prokaryotic organisms are well known and routine in the art and are described throughout the literature (See, for example, Jiang et al. 2013. Nat. Biotechnol. 31:233-239; Ran et al. Nature Protocols 8:2281-2308 (2013)). General guides to various plant transformation methods known in the art include Miki et al. (“Procedures for Introducing Foreign DNA into Plants” in Methods in Plant Molecular Biology and Biotechnology, Glick, B. R. and Thompson, J. E., Eds. (CRC Press, Inc., Boca Raton, 1993), pages 67-88) and Rakowoczy-Trojanowska (Cell. Mol. Biol. Lett. 7:849-858 (2002)).
A polynucleotide and/or polypeptide can be introduced into a host organism or its cell (optionally a plant, plant part, and/or plant cell) in any number of ways that are well known in the art. The methods of the invention do not depend on a particular method for introducing one or more nucleotide sequences into the organism (e.g., a plant), only that they gain access to the interior of at least one cell of the organism. When more than one polynucleotide is to be introduced, it can be assembled as part of a single nucleic acid construct, as separate nucleic acid constructs, can be located on the same or different nucleic acid constructs, and/or as a complex (e.g., a ribonucleoprotein). A polynucleotide and/or polypeptide can be introduced into the cell of interest in a single transformation event, or in separate transformation events, or, alternatively, a polynucleotide and/or polypeptide can be incorporated into a plant as part of a breeding protocol.
Provided according to embodiments of the present invention are nucleic acid constructs that can be useful as a reporter (e.g., a reporter for an editing system) and/or that can be used to report on modification of a target nucleic acid and/or on gene editing. A nucleic acid construct of the present invention may be used to report on the activity of an editing system (e.g., a genome editing tool) such as, but not limited to, an editing system that uses a reverse transcriptase. In some embodiments, an editing system in a system and/or method of the present invention comprises a CRISPR-Cas effector protein.
A nucleic acid construct, composition, system, and/or method of the present invention may mimic the exact condition in which an editing system is used and/or intended to be used in the native sequence context of the editing system. Since all or a portion of a sequence of a target nucleic acid (e.g., a native nucleic acid) is included in a nucleic acid construct of the present invention, the nucleic acid construct and/or a composition, system, and/or method of the present invention can mimic/model the exact condition (e.g., the sequence) of the target nucleic acid (e.g., in a cell and/or organism) and/or can report on the modification of the target nucleic acid by an editing system and thereby report on the editing system. In some embodiments, a nucleic acid construct of the present invention is a plasmid-based reporter system and/or is present and/or used in a plasmid-based reporter system.
In some embodiments, a nucleic acid construct and/or method of the present invention may be used to measure and/or determine the efficiency and/or effectiveness of a spacer in an editing system. For example, in some embodiments, a nucleic acid construct and/or method of the present invention may be used to measure and/or determine the efficiency and/or effectiveness of a spacer in an editing system based on a modification to a target nucleic acid using the spacer and editing system. In some embodiments, a nucleic acid construct and/or method of the present invention may be used to measure and/or determine the efficiency and/or effectiveness of an editing system and/or of a nuclease, base editor, and/or reverse transcriptase in modifying a target nucleic acid. The efficiency and/or effectiveness of an editing system and/or a component thereof (e.g., a spacer, a nuclease, a base editor, and/or a reverse transcriptase) may be performed in any organism (e.g., an animal, a plant, a fungus, an archaeon, or a bacterium) such as in a cell of any organism in vitro or in vivo. In some embodiments, the efficiency and/or effectiveness of an editing system and/or a component thereof may be measured and/or determined by quantifying and/or measuring the frequency and/or amount of a detectable signal (e.g., a fluorescent signal). For example, the frequency and/or amount of a fluorescent signal (e.g., the number of fluorescing cells and/or fluorescence intensity in a respective cell) may be measured, optionally by using flow cytometry and/or fluorescence-activated single cell sorting (FACS). In some embodiments, determining and/or measuring the efficiency and/or effectiveness of a first editing system and/or a component thereof may comprise measuring the frequency and/or amount of a detectable signal (e.g., a fluorescent signal) in one or more cell(s) comprising the first editing system and comparing the frequency and/or amount of the detectable signal in the one or cell(s) comprising the first editing system to the frequency and/or amount of another detectable signal for one or more cell(s) comprising a second editing system that is different than the first editing system. In some embodiments, determining and/or measuring the efficiency and/or effectiveness of an editing system and/or a component thereof may comprise measuring the frequency and/or amount of a detectable signal (e.g., a fluorescent signal) in one or more cell(s) comprising the editing system at a first point in time (e.g., at initial introduction of the editing system into the one or more cell(s)) and comparing the frequency and/or amount of the detectable signal in the one or cell(s) at the first point in time to the frequency and/or amount of the detectable signal for the one or more cell(s) at a second point in time that is different than the first point in time (e.g., 1, 2, 3, 4, or more hour(s) or day(s) after introduction of the editing system into the one or more cell(s)).
A nucleic acid construct of the present invention may comprise a promoter; a first nucleic acid including a target sequence; and a second nucleic acid encoding a polypeptide (e.g., a fluorescent polypeptide), wherein the promoter is operably associated with the first and second nucleic acids and the first nucleic acid is between the promoter and the second nucleic acid, and wherein the first nucleic acid includes a stop codon (e.g., TGA, TAG, TAA, UGA, UAG, and/or UAA) that prevents translation of the second nucleic acid or the first nucleic acid includes a codon (e.g., a UGG codon) that, upon modification of the codon to a stop codon, prevents translation of the second nucleic acid. One or more (e.g., 1, 2, 3, 4, or more) stop codon(s) may be present in the first nucleic acid. Accordingly, such a nucleic acid construct can be configured to prevent or not allow translation of the second nucleic acid when a stop codon is present in the first nucleic acid and to allow translation when the stop codon is modified (e.g., by an editing system that modifies and/or is configured to modify the target sequence and/or stop codon), which can thereby allow for production of the polypeptide (e.g., fluorescent polypeptide). Alternatively, such a nucleic acid construct can be configured to allow translation of the second nucleic acid when a codon (e.g., a UGG codon) is present in the first nucleic acid and to prevent or not allow translation of the second nucleic acid when the codon is modified (e.g., by an editing system that modifies and/or is configured to modify the target sequence and/or the codon), which can thereby prevent or stop production of the polypeptide (e.g., fluorescent polypeptide). One or more (e.g., 1, 2, 3, 4, or more) codon(s) may modified to provide a stop codon to thereby prevent or stop production of the polypeptide (e.g., fluorescent polypeptide). In the first nucleic acid, any in frame codon can be modified into a stop codon (e.g., using Prime Editing or Redraw), which can thereby modify (e.g., reduce or stop) production of the polypeptide (e.g., fluorescent polypeptide). Thus, in some embodiments, an editing system modifies a codon in the first nucleic acid in frame such that the codon becomes a stop codon and such that the second nucleic acid is not translated or translation is prevented. In some embodiments, the first nucleic acid comprises a UGG or UGA codon that is modified (e.g., with a base editing) to a stop codon (e.g., UAA). In some embodiments, the second nucleic acid encodes a polypeptide that can provide a detectable signal. For example, in some embodiments, the second nucleic acid encodes all or a portion of a fluorescent polypeptide or the second nucleic acid encodes all or a portion of a luciferase. In some embodiments, by including one or more stop codon(s) in the first nucleic acid and/or by modifying one or more codon(s) to a stop codon may reduce background noise in a method of the present invention.
In some embodiments, a nucleic acid construct may comprise a promoter; a first nucleic acid including a target sequence; and a second nucleic acid encoding a recombinase (e.g., a Cre recombinase), wherein the promoter is operably associated with the first and second nucleic acids and the first nucleic acid is between the promoter and the second nucleic acid, and wherein the first nucleic acid includes a stop codon (e.g., TGA, TAG, TAA, UGA, UAG, and/or UAA) that prevents translation of the second nucleic acid or the first nucleic acid includes a codon (e.g., a UGG codon) that, upon modification of the codon to a stop codon, prevents translation of the second nucleic acid. Accordingly, such a nucleic acid construct can be configured to prevent or not allow translation of the second nucleic acid when a stop codon is present in the first nucleic acid and to allow translation when the stop codon is modified (e.g., by an editing system that modifies and/or is configured to modify the target sequence and/or stop codon), which can thereby allow for production of the recombinase. Alternatively, such a nucleic acid construct can be configured to allow translation of the second nucleic acid when a codon (e.g., a UGG codon is present in the first nucleic acid and to prevent or not allow translation of the second nucleic acid when the codon is modified (e.g., by an editing system that modifies and/or is configured to modify the target sequence and/or codon), which can thereby prevent or stop production of the recombinase. In the first nucleic acid, any in frame codon can be modified into a stop codon (e.g., using Prime Editing or Redraw), which can thereby modify (e.g., reduce or stop) production of the recombinase. Thus, in some embodiments, an editing system modifies a codon in the first nucleic acid in frame such that the codon becomes a stop codon and such that the recombinase is not translated or translation is prevented. In some embodiments, the first nucleic acid comprises a UGG or UGA codon that is modified (e.g., with a base editing) to a stop codon (e.g., UAA). In some embodiments, a nucleic acid construct of the present invention comprising a nucleic acid encoding a recombinase (e.g., a Cre recombinase) and/or a method using the same may be used to increase the sensitivity of the system and/or increase the sensitivity of the method of reporting on and/or determining and/or measuring the efficiency and/or effectiveness of an editing system.
Exemplary recombinases include, but are not limited to, Cre recombinases, serine recombinases, and/or tyrosine recombinases. In some embodiments, a recombinase comprises a sequence having at least about 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or more sequence identity to any one of SEQ ID NOs:67-69. In some embodiments, a recombinase comprises a sequence having about 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5%. 99.9% or 100% identity to any one of SEQ ID NOs:67-69.
The first nucleic acid of a nucleic acid construct of the present invention may comprise a protein coding nucleic acid and/or a noncoding nucleic acid. In some embodiments, the first nucleic acid is a protein coding nucleic acid. In some embodiments, the first nucleic acid is a noncoding nucleic acid (e.g., a noncoding nucleic acid that can be transcribed). In some embodiments, the first nucleic acid comprises a protein coding nucleic acid and a noncoding nucleic acid.
A first nucleic acid of the present invention may comprise a protospacer (i.e., a sequence that is fully or substantially complementary to (and can hybridize to) a spacer sequence of a guide nucleic acid). A protospacer may have a length of about 10 nucleotides to about 20 or 30 nucleotides such as about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 nucleotides. In some embodiments, the protospacer may have a length of about 10 nucleotides to about 20 nucleotides such as about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 nucleotides. A first nucleic acid may comprise about 10 consecutive nucleotides to about 100 consecutive nucleotides that are upstream and/or downstream of a protospacer sequence such as about 10 to about 30, 10 to about 50, about 10 to about 80, about 20 to about 80, or about 20 to about 50 consecutive nucleotides or about 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 consecutive nucleotides that are upstream and/or downstream of a protospacer sequence. Thus, the first nucleic acid may comprise, in order, optionally about 10 consecutive nucleotides to about 100 consecutive nucleotides, a protospacer, and optionally about 10 consecutive nucleotides to about 100 consecutive nucleotides. In some embodiments, a first nucleic acid of the present invention comprises a protospacer having a length of about 10 nucleotides to about 20 nucleotides and the first nucleic acid further comprises about 10 consecutive nucleotides to about 100 consecutive nucleotides that are upstream and/or downstream of the protospacer sequence. In some embodiments, a first nucleic acid of the present invention has a total length of about 10, 20, 30, 40, or 50 nucleotides to about 100, 150, 200, 220, or 250 nucleotides. In some embodiments, a first nucleic acid has a length of about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, or 250 nucleotides.
The first nucleic acid comprises a target sequence. A “target sequence” as used herein refers to a sequence that is at least about 90%, 90.5%, 91%, 91.5%, 92%, 92.5%, 93%, 93.5%, 94%, 94.5%, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, 99.5%, or 100% identical to a target nucleic acid as defined herein (e.g., a native nucleic acid (i.e., a nucleic acid sequence that is naturally occurring in a cell (e.g., a plant cell or other eukaryotic cell such as a mammalian cell))). In this manner, the nucleic acid construct may mimic the exact condition in which an editing system is used and/or intended to be used in a cell (e.g., the editing system may be intended to be used to modify a native nucleic acid in the cell). A target sequence thus corresponds to and is based on a particular target nucleic acid, thereby a target sequence has a corresponding target nucleic acid. The description provided herein for a target nucleic acid (e.g., components, compositions, systems, expression cassettes, and/or methods such as methods for modifying a target nucleic acid) can equally apply to a target sequence. In some embodiments, a target sequence differs from a corresponding target nucleic acid in that the target sequence at least includes a stop codon that is not present in the corresponding target nucleic acid. A stop codon may be included at any position and/or region of the target sequence. A target sequence comprises a protospacer and the protospacer of the target sequence may be about 90%, 90.5%, 91%, 91.5%, 92%, 92.5%, 93%, 93.5%, 94%, 94.5%, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, 99.5%, or 100% identical to a protospacer present in a target nucleic acid. In some embodiments, a target sequence may comprise a first number of consecutive nucleotides that correspond to the same number of consecutive nucleotides that are upstream of a protospacer present in a target nucleic acid, a protospacer that corresponds to the protospacer present in the target nucleic acid, and a second number of consecutive nucleotides that correspond to the same number of consecutive nucleotides that are downstream of the protospacer present in the target nucleic acid. The first number and/or second number of consecutive nucleotides in the target sequence may each individually be about 90%, 90.5%, 91%, 91.5%, 92%, 92.5%, 93%, 93.5%, 94%, 94.5%, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, 99.5%, or 100% identical to the consecutive nucleotides that are upstream and/or downstream, respectively, of the protospacer present in the target nucleic acid.
In some embodiments, the first nucleic acid comprises a sequence that is about 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to a target nucleic acid (e.g., a native nucleic acid in a cell and/or organism). In some embodiments, the first nucleic acid comprises a sequence that is 100% identical to a native nucleic acid. The target sequence may be a genomic sequence from any organism (e.g., a plant or eukaryote such as a mammal). In some embodiments, the target sequence is a genomic sequence from a model organism such as, but not limited to, Escherichia coli, an immortalized human cell line (e.g., HEK293, HeLa, etc.), Caenorhabditis elegans, and/or Drosophila Melanogaster. In some embodiments, the target sequence is a genomic sequence from a non-model organism. Exemplary non-model organisms include, but are not limited to crop plants (e.g., fruit crop plants, vegetable crop plants, and/or field crop plants) and/or animals such as humans, primates and/or mice. In some embodiments, the non-model organism is a crop plant such as corn, soybean, wheat, or canola. In some embodiments, the non-model organism is an animal for testing and/or use of a human therapeutic.
In some embodiments, a first nucleic acid may comprise about 10 consecutive nucleotides to about 100 consecutive nucleotides that are present upstream and/or downstream of a protospacer that is present in a target nucleic acid such as about 10 to about 30, about 10 to about 50, about 10 to about 80, about 20 to about 80, or about 20 to about 50 consecutive nucleotides or about 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100 consecutive nucleotides that are present upstream and/or downstream of the protospacer present in the target nucleic acid, which may preserve the sequence-context of the target nucleic acid relative to the first nucleic acid. In some embodiments, a first nucleic acid may comprise a target sequence that comprises about 10-100 consecutive nucleotides that correspond to about 10-100 consecutive nucleotides that are upstream of a protospacer that is present in a target nucleic acid, a protospacer that corresponds to the protospacer of the target nucleic acid, and about 10-100 consecutive nucleotides that correspond to about 10-100 consecutive nucleotides that are downstream of the protospacer of the target nucleic acid, which may preserve the sequence-context of the target nucleic acid relative to the target sequence. In some embodiments, a first nucleic acid may comprise a target sequence that includes about 10 consecutive nucleotides to about 100 consecutive nucleotides upstream and/or downstream of a protospacer, wherein the consecutive nucleotides upstream and/or downstream of the protospacer each individually have a sequence that is least about 90%, 90.5%, 91%, 91.5%, 92%, 92.5%, 93%, 93.5%, 94%, 94.5%, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, 99.5%, or 100% identical to a region of the corresponding target nucleic acid for the target sequence, which may preserve the sequence-context of the target nucleic acid relative to the target sequence.
A nucleic acid construct of the present invention may comprise a linker. In some embodiments, a nucleic acid construct of the present invention comprises a linker that encodes a self-cleaving peptide. A “self-cleaving peptide” as used herein refers to a peptide that provides cleavage between its N-terminus and its immediate downstream polypeptide, optionally due to ribosome skipping. Exemplary self-cleaving peptides are known in the art and include, but are not limited to, porcine teschovirus-1 (P2A) peptides, foot-and-mouth disease virus (FMDV) 2A (e.g., FMDV 2A) peptides, equine rhinitis A virus (ERAV) 2A peptides, Thoseaasigna virus 2A (T2A) peptides, and/or self-cleaving peptides described in Kim et al. (2011) PLoS ONE 6(4): e18556, which is incorporated herein by reference. In some embodiments, a linker and/or self-cleaving peptide has a sequence that is at least 70%, 75%, 80%, 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to any one of SEQ ID NOs:59-66. In some embodiments, a linker and/or self-cleaving peptide comprises a sequence of any one of SEQ ID NOs:59-66. In some embodiments, a nucleic acid construct of the present invention comprises a linker that encodes a porcine teschovirus-1 (P2A) peptide. A linker (e.g., a linker encoding a self-cleaving peptide) may be between a first nucleic acid and second nucleic acid.
In some embodiments, a nucleic acid construct of the present invention from the start of the first nucleic acid (e.g., 5′ end) to the end of the second nucleic acid (3′ end) has a length of about 1500 consecutive nucleotides or less. In some embodiments, from the 5′ end of the first nucleic acid to the 3′ end of the second nucleic acid, the nucleic acid construct has a length of about 100, 200, 300, 400, 500, 600, 700, 800, or 900 consecutive nucleotides to about 1000, 1100, 1200, 1300, 1400, or 1500 consecutive nucleotides. In some embodiments, from the 5′ end of the first nucleic acid to the 3′ end of the second nucleic acid, the nucleic acid construct has a length of about 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, or 1500 consecutive nucleotides.
A method of the present invention may comprise providing a nucleic acid construct of the present invention that comprises a target sequence, contacting an editing system and the target sequence, wherein, responsive to modification of the target sequence, a detectable signal (e.g., a fluorescent signal) appears or is reduced; and detecting the appearance or a reduction of the detectable signal. A method of the present invention can be used to detect modification of a target sequence and the modification can be done and/or carried out by the editing system. The method may comprise introducing a nucleic acid construct of the present invention to a cell (e.g., a plant cell, other eukaryotic cell such as a mammalian cell, or prokaryotic cell) comprising a target nucleic acid (e.g., a native nucleic acid). A native nucleic acid may comprise a sequence that is at least about 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to the target sequence and/or first nucleic acid. In this manner, the nucleic acid construct may mimic the exact condition (e.g., the exact sequence) in which an editing system is used and/or intended to be used in a cell (e.g., the editing system may be intended to be used to modify the native nucleic acid in the cell and thus the nucleic acid construct can mimic/model the exact or substantially the same sequence of the native nucleic acid). In some embodiments, the native nucleic acid comprises a sequence that is about 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100% identical to the target sequence. In some embodiments, the native nucleic acid comprises a sequence that is 100% identical to the target sequence. A method of the present invention may be performed and/or carried out in any organism (e.g., an animal, a plant, a fungus, an archaeon, or a bacterium) such as in a cell of any organism in vitro or in vivo.
A method of the present invention may comprise introducing the editing system into the cell. The editing system may comprise a nuclease, base editor, and/or reverse transcriptase and the editing system may be used in a method of the present invention. In some embodiments, the editing system modifies and/or is configured to modify a target sequence in a nucleic acid construct of the present invention and/or may be configured to modify a target nucleic acid (e.g., a native nucleic acid) in a cell. In some embodiments, the nucleic acid construct comprising the first and second nucleic acids of the present invention may further comprise at least a portion or all of the editing system and/or a second nucleic acid construct may encode at least a portion or all of the editing system. In some embodiments, two or more different nucleic acid constructs (e.g., a nucleic acid construct comprising the first and second nucleic acids of the present invention and a nucleic acid encoding at least a portion of the editing system) may be introduced to a cell (e.g., a plant cell or eukaryotic cell such as a mammalian cell) at the same time or at different times (e.g., concurrently or sequentially) using the same or a different method. In some embodiments, two or more different nucleic acid constructs may be present in the same composition or may be present in separate compositions that are introduced to a cell.
The editing system may modify the target sequence in the nucleic acid construct of the present invention that is introduced into a cell, and the cell may comprise a native nucleic acid that may have a sequence similar or substantially identical to the target sequence. In some embodiments, the target sequence is modified using homologous recombination and/or prime editing. In some embodiments, the target sequence is modified by a nuclease and optionally the modification to the target sequence may provide a frameshift mutation. In some embodiments, the modification to the target sequence is not a nuclease-induced frameshift mutation. In some embodiments, the modification to the target sequence is a nuclease-induced frameshift mutation and at least one additional different mutation than a nuclease-induced frameshift mutation. In some embodiments, the target sequence is modified by an adenine base editor and optionally the modification removes a stop codon that prevents translation of the second nucleic acid to thereby allow for translation of the second nucleic acid. A stop codon may be removed according to a method of the present invention by deletion of the stop codon and/or by converting one or more nucleic acid residues to a different residue that removes the stop codon. Alternatively, a deletion and/or insertion may result in and/or restore an open reading frame. In some embodiments, the target sequence is modified by a reverse transcriptase and optionally the modification removes a stop codon that prevents translation of the second nucleic acid to thereby allow for translation of the second nucleic acid. In some embodiments, the target sequence is modified by a cytosine base editor and optionally the modification converts a UGG codon or a UGA codon to a stop codon to thereby prevent translation of the second nucleic acid. In some embodiments, UGG codon or a UGA codon may be converted to a stop codon according to a method of the present invention by converting one or more nucleic acid base(s) to a different base, and the base conversion results in and/or provides a UGG codon or a UGA codon being changed to a stop codon.
A method of the present invention may comprise quantifying the amount of modification of the target sequence. In some embodiments, the method and/or step of quantifying the amount of modification of the target sequence may comprise measuring the frequency, intensity (e.g., brightness), level, and/or amount of the detectable signal. Methods of measuring the frequency, intensity, level, and/or amount of a detectable signal (e.g., a fluorescence signal) are known in the art and such methods and/or techniques include, but are not limited to, fluorometry and/or flow cytometry and/or use of an assay (e.g., a luminescence assay). The frequency, intensity, level, and/or amount of the detectable signal may correspond to the amount of modification of the target sequence. In some embodiments, the method comprises correlating the amount of modification of the target sequence to an estimated amount of modification for a native nucleic acid using the editing system (e.g., optionally the same editing system used to modify the target sequence and the native nucleic acid).
In some embodiments, the detectable signal is a fluorescence signal. The fluorescence signal may be provided by any fluorescent polypeptide. In some embodiments, the fluorescent polypeptide is a reporter protein or a portion thereof that can fluoresce. In some embodiments, the fluorescent polypeptide exhibits fluorescence when exposed to light (e.g., in a particular wavelength range). In some embodiments, the fluorescent signal may be quantifiable such as by using fluorometry and/or flow cytometry. Exemplary fluorescent polypeptides include, but are not limited to, a green fluorescent protein (GFP) or (e.g., OFF, GFP-2, tagGFP, turboGFP, enhanced GFP (EGFP), Emerald, Azami Green, Monomeric Azami Green, CopGFP, AceGFP, ZsGreen1), yellow fluorescent proteins (e.g. YFP, EYFP, Citrine, Venus, YPet, PhiYFP, ZsYellow1), blue fluorescent proteins (e.g. EBFP, EBFP2, Azurite, mKalama1, GFPuv, Sapphire, T-sapphire,), cyan fluorescent proteins (e.g. ECFP, Cerulean, CyPet, AmCyan1, Midoriishi-Cyan), red fluorescent proteins (mKate, mKate2, mPlum, DsRed monomer, mCherry, mRFP1, DsRed-Express, DsRed2, DsRed-Monomer, HcRed-Tandem, HcRed1, AsRed2, eqFP611, mRasberry, mStrawberry, Jred), and/or orange fluorescent proteins (mOrange, mKO, Kusabira-Orange, Monomeric Kusabira-Orange, mTangerine, tdTomato).
In some embodiments, the detectable signal is luminescence. Luminescence may be provided by a luciferase. Thus, the polypeptide providing the detectable signal may comprise all or a portion of a luciferase that can provide luminescence. In some embodiments, the luminescence signal may be quantifiable such as by using a luminescence assay. Exemplary luciferases include, but are not limited to, firefly luciferase and/or Renilla luciferase.
In some embodiments, a method of the present invention comprises providing a nucleic acid construct including: a promoter; a first nucleic acid including a target sequence; and a second nucleic acid encoding a polypeptide (e.g., a fluorescent polypeptide) that provides a detectable signal (e.g., a fluorescent signal), wherein the promoter is operably associated with the first and second nucleic acids and the first nucleic acid is between the promoter and the second nucleic acid, and wherein the first nucleic acid includes a stop codon (e.g., TGA, TAG, TAA, UGA, UAG, and/or UAA) that prevents translation of the second nucleic acid or the first nucleic acid includes a codon (e.g., a UGG codon) that, upon modification of the codon to a stop codon, prevents translation of the second nucleic acid; contacting an editing system and the target sequence, wherein, responsive to modification of the target sequence, the detectable signal appears or is reduced; and detecting the appearance or a reduction of the detectable signal, thereby detecting modification of the target sequence. In some embodiments, the second nucleic acid encodes all or a portion of a fluorescent polypeptide. In some embodiments, the second nucleic acid encodes all or a portion of a luciferase.
In some embodiments, the editing system modifies the target sequence and, responsive to the modification, the stop codon is removed and thereby the second nucleic acid encoding the polypeptide (e.g., fluorescent polypeptide) is translated. Thus, prior to contacting the editing system and the target sequence, the detectable signal may be absent and, after contacting the editing system and the target sequence, the detectable signal may be present. Accordingly, the detecting step may comprise detecting the appearance of the detectable signal when, prior to contacting the editing system and the target sequence, the detectable signal was absent and, after contacting the editing system and the target sequence, the detectable signal is present.
In some embodiments, the editing system modifies the target sequence and, responsive to the modification, a codon (e.g., a UGG codon) is converted to a stop codon thereby preventing or stopping translation of the second nucleic acid encoding the polypeptide (e.g., fluorescent polypeptide). Thus, prior to contacting the editing system and the target sequence, the detectable signal may be present and, after contacting the editing system and the target sequence, the detectable signal may be reduced or absent. Accordingly, the detecting step may comprise detecting a reduction of the detectable signal when, prior to contacting the editing system and the target sequence, the detectable signal was present and, after contacting the editing system and the target sequence, the detectable signal is reduced or absent.
In some embodiments, a method of the present invention comprises providing a nucleic acid construct including: a promoter; a first nucleic acid including a target sequence; and a second nucleic acid encoding a recombinase (e.g., a Cre recombinase), wherein the promoter is operably associated with the first and second nucleic acids and the first nucleic acid is between the promoter and the second nucleic acid, and wherein the first nucleic acid includes a stop codon (e.g., TGA, TAG, TAA, UGA, UAG, and/or UAA) that prevents translation of the second nucleic acid or the first nucleic acid includes a codon (e.g., a UGG codon) that, upon modification of the codon to a stop codon, prevents translation of the second nucleic acid; contacting an editing system and the target sequence, wherein, responsive to modification of the target sequence, a detectable signal (e.g., a fluorescent signal) appears; and detecting the appearance of the detectable signal, thereby detecting modification of the target sequence.
The detectable signal may be produced responsive to the recombinase modifying a third nucleic acid encoding a polypeptide (e.g., a fluorescent polypeptide) that provides the detectable signal. Modification of the third nucleic acid by the recombinase may allow for expression of the polypeptide (e.g., fluorescent polypeptide). In some embodiments, the recombinase removes a stop codon from the third nucleic acid thereby allowing for expression of the polypeptide (e.g., fluorescent polypeptide). The third nucleic acid may be separate from the nucleic acid construct encoding the recombinase. In some embodiments, the third nucleic acid is present in genomic DNA of a cell in which the nucleic acid construct encoding the recombinase is present and/or introduced. In some embodiments, the third nucleic acid encodes all or a portion of a fluorescent polypeptide. In some embodiments, the third nucleic acid encodes all or a portion of a luciferase.
In some embodiments, the editing system modifies the target sequence and, responsive to the modification, the stop codon is removed and thereby the second nucleic acid encoding the recombinase is translated. Thus, prior to contacting the editing system and the target sequence, the detectable signal may be absent and, after contacting the editing system and the target sequence, the detectable signal may be present. Accordingly, the detecting step may comprise detecting the appearance of the detectable signal when, prior to contacting the editing system and the target sequence, the detectable signal was absent and, after contacting the editing system and the target sequence, the detectable signal is present.
In some embodiments, the editing system modifies the target sequence and, responsive to the modification, a codon (e.g., a UGG codon) is converted to a stop codon thereby preventing translation of the second nucleic acid encoding the recombinase. Thus, prior to contacting the editing system and the target sequence, the detectable signal may be present and, after contacting the editing system and the target sequence, the detectable signal may be reduced or absent. Accordingly, the detecting step may comprise detecting a reduction of the detectable signal when, prior to contacting the editing system and the target sequence, the detectable signal was present and, after contacting the editing system and the target sequence, the detectable signal is reduced or absent.
In some embodiments, a method of determining and/or measuring the efficiency and/or effectiveness of a first editing system and/or a component thereof in modifying a target sequence and/or target nucleic acid is provided. The method may comprise providing a nucleic acid construct including: a promoter; a first nucleic acid including the target sequence; and a second nucleic acid encoding a polypeptide (e.g., a fluorescent polypeptide) that provides a first detectable signal (e.g., a fluorescent signal), wherein the promoter is operably associated with the first and second nucleic acids and the first nucleic acid is between the promoter and the second nucleic acid, and wherein the first nucleic acid includes a stop codon (e.g., TGA, TAG, and/or TAA) that prevents translation of the second nucleic acid or the first nucleic acid includes a codon (e.g., a UGG codon) that, upon modification of the codon to a stop codon, prevents translation of the second nucleic acid; contacting the first editing system and the target sequence, wherein, responsive to modification of the target sequence, the first detectable signal appears or is reduced; and measuring the frequency and/or amount (e.g., intensity) of the first detectable signal to provide a first signal amount; separately contacting a second editing system and the target sequence, wherein, responsive to modification of the target sequence, a second detectable signal appears or is reduced, and wherein the first editing system is different than the second editing system; measuring the frequency and/or amount (e.g., intensity) of the second detectable signal to provide a second signal amount; and comparing the first signal amount to the second signal amount, wherein a greater amount for the first signal amount compared to the second signal amount indicates an increased efficiency and/or effectiveness of the first editing system and/or a component thereof in modifying the target sequence and/or target nucleic acid. In some embodiments, the first editing system comprises a first guide nucleic acid and the second editing system comprises a second guide nucleic acid and the first and second editing systems are different in that the first guide nucleic acid is different than the second guide nucleic acid such as in sequence and/or length.
In some embodiments, a method of determining and/or measuring the efficiency and/or effectiveness of a first editing system and/or a component thereof in modifying a target sequence and/or target nucleic acid, the method comprises providing a nucleic acid construct including: a promoter; a first nucleic acid including a target sequence; and a second nucleic acid encoding a recombinase (e.g., a Cre recombinase), wherein the promoter is operably associated with the first and second nucleic acids and the first nucleic acid is between the promoter and the second nucleic acid, and wherein the first nucleic acid includes a stop codon (e.g., TGA, TAG, and/or TAA) that prevents translation of the second nucleic acid or the first nucleic acid includes a codon (e.g., a UGG codon) that, upon modification of the codon to a stop codon, prevents translation of the second nucleic acid; contacting the first editing system and the target sequence, wherein, responsive to modification of the target sequence, a first detectable signal (e.g., a fluorescent signal) appears; measuring the frequency and/or amount (e.g., intensity) of the first detectable signal to provide a first signal amount; separately contacting a second editing system and the target sequence, wherein, responsive to modification of the target sequence, a second detectable signal appears, and wherein the first editing system is different than the second editing system; measuring the frequency and/or amount (e.g., intensity) of the second detectable signal to provide a second signal amount; and comparing the first signal amount to the second signal amount, wherein a greater amount for the first signal amount compared to the second signal amount indicates an increased efficiency and/or effectiveness of the first editing system and/or a component thereof in modifying the target sequence and/or target nucleic acid. In some embodiments, the first editing system comprises a first guide nucleic acid and the second editing system comprises a second guide nucleic acid and the first and second editing systems are different in that the first guide nucleic acid is different than the second guide nucleic acid such as in sequence and/or length.
Embodiments of the present invention can provide a plasmid-based reporter system that can report on any editing system such as, but not limited to, gene editing tools including and/or involving nucleases, base editors, homologous recombination, and/or reverse transcriptase. In some embodiments, a nucleic acid construct of the present invention (e.g., a reporter) can test the activity of an editing system in the intended sequence environment of any genomic sequence and/or target, which can provide higher confidence on the likelihood of success in applying the editing system outside of the reporter context in a non-model organism or a cell thereof (e.g., higher confidence on the likelihood of success in modifying a native sequence in an organism). In some embodiments, a nucleic acid construct of the present invention can report on two or more (e.g., 2, 3, 4, 5, or more) different types of editing systems. For example, a nucleic acid construct of the present invention can report on a gene editing tool than provides a nuclease-induced frameshift mutation and at least one different gene editing tool than one that provides a nuclease-induced frameshift mutation.
In some embodiments, a nucleic acid construct and/or system of the present invention preserves the sequence-context of a native nucleic acid present in a cell (e.g., by inserting in a nucleic acid construct of the present invention a target sequence that corresponds to the native nucleic acid and includes, in the same order as in the native nucleic acid, a protospacer that is present in the native nucleic acid and about 20 bases that are present upstream and/or downstream of the protospacer). Preserving the sequence context can provide several advantages. One advantage is that, by inserting a significant region around a protospacer, genome editing tools that work outside of the protospacer of an editing system can be tested. For example, prime editing enables targeted mutagenesis outside of the protospacer, and the sequence context of several bases adjacent to the spacer (e.g., 10-100) can be important parameters for optimizing the tool performance for prime editing. This is because the pegRNA that guides prime editors contain parts of sequences around the protospacer region to program the reverse transcriptase activity. Therefore, in order to optimize such editing tools for their use in an endogenous context, the reporter system must also encompass the same sequence range.
In some embodiments, a nucleic acid construct, composition, system, and/or method of the present invention can quickly and accurately optimize guide RNA architecture that targets a native sequence in the genome of a non-model organisms. In some embodiments, a nucleic acid construct, composition, and/or system of the present invention encodes priming and templating necessary for reverse transcriptase activity. In some embodiments, a nucleic acid construct, composition, system, and/or method of the present invention reports on and/or detects reverse transcriptase activity.
According to some embodiments of the present invention, a reporter system can be provided and may be used to optimize the activity of an editing system (e.g., an editing tool) in its intended target in native genomic sequences. A nucleic acid construct and/or reporter of the present invention can be encoded in a plasmid. In some embodiments, a nucleic acid construct and/or promoter of the present invention comprises a promoter followed by a fluorescent protein whose brightness will be measured. In some embodiments, as shown in
Depending on the editing system being tested, different deleterious mutations that prevent the translation of a downstream fluorescent protein can be introduced at a specific location (usually a stop codon, at the editing tool's target window) which can be used to demonstrate and/or report on the activity of the editing system being tested. For example, as shown in
In some embodiments, a nucleic acid construct and/or reporter of the present invention can have heightened sensitivity. In some embodiments, a system and/or reporter having heightened sensitivity provides a signal that is generated from an editing activity that is amplified through a secondary circuit. In some embodiments, a system and/or reporter involving a secondary circuit (e.g., a secondary circuit that provides a detectable signal such as a fluorescent signal) has increased sensitivity compared to a system and/or reporter that does not involve a secondary circuit. An example of a secondary circuit includes, but is not limited to, a recombinase-responsive nucleic acid construct and/or a recombinase-responsive circuit (e.g., a nucleic acid that can be acted on by a recombinase). For example, as shown in
In some embodiments, a polynucleotide, expression cassette and/or vector of the invention may be codon optimized for expression in an organism (e.g., an animal, a plant, a bacterium, an archaeon, and the like). In some embodiments, the polynucleotides, expression cassettes, and/or vectors may be codon optimized for expression in a plant, optionally a dicot plant or a monocot plant.
In some embodiments, the polynucleotides, nucleic acid constructs, expression cassettes or vectors of the invention that are optimized for expression in an organism (e.g., a plant or eukaryote) may be about 70% to 100% identical (e.g., about 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5% or 100%) to the polynucleotides, nucleic acid constructs, expression cassettes or vectors encoding the same but which have not been codon optimized for expression in the organism (e.g., the plant or eukaryote).
The nucleic acid constructs of the invention and/or guide nucleic acids may be comprised in one or more expression cassettes as described herein. In some embodiments, a nucleic acid construct of the invention may be comprised in the same or in a separate expression cassette or vector from that comprising a guide nucleic acid.
As described herein, the nucleic acids of the invention and/or expression cassettes and/or vectors comprising the same may be codon optimized for expression in an organism. An organism useful with this invention may be any organism or cell thereof for which nucleic acid modification may be useful. An organism can include, but is not limited to, any animal, any plant, any fungus, any archaeon, or any bacterium. In some embodiments, the organism may be a plant or cell thereof.
In some embodiments, an expression cassette of the invention may be codon optimized for expression in a dicot plant or it may be codon optimized for expression in a monocot plant. In some embodiments, the expression cassettes of the invention may be used in a method of modifying a target sequence and/or target nucleic acid in a plant or plant cell, the method comprising introducing one or more expression cassettes of the invention into the plant or plant cell, thereby modifying the target sequence and/or target nucleic acid in the plant or plant cell to produce a plant or plant cell comprising the modified target sequence and/or modified target nucleic acid. In some embodiments, an expression cassette and/or vector of the invention may be introduced via an engineered bacterial cell comprising one or more of the polynucleotides, expression cassettes and/or vectors of the invention. In some embodiments, the method may further comprise regenerating the plant cell that comprises the modified target sequence and/or modified target nucleic acid to produce a plant comprising the modified target sequence and/or modified target nucleic acid.
In some embodiments, the nucleic acid constructs, expression cassettes or vectors of the invention that are optimized for expression in a plant may be about 70% to 100% identical (e.g., about 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 99.5% or 100%) to the nucleic acid constructs, expression cassettes or vectors comprising the same polynucleotide(s) but which have not been codon optimized for expression in a plant.
A target nucleic acid of any plant or plant part may be modified using the nucleic acid constructs of the invention. Any plant (or groupings of plants, for example, into a genus or higher order classification) may be modified using a polypeptide and/or polynucleotide of the present invention including an angiosperm, a gymnosperm, a monocot, a dicot, a C3, C4, CAM plant, a bryophyte, a fern and/or fern ally, a microalgae, and/or a macroalgae. A plant and/or plant part useful with this invention may be a plant and/or plant part of any plant species/variety/cultivar. The term “plant part,” as used herein, includes but is not limited to, embryos, pollen, ovules, seeds, leaves, stems, shoots, flowers, branches, fruit, kernels, ears, cobs, husks, stalks, roots, root tips, anthers, plant cells including plant cells that are intact in plants and/or parts of plants, plant protoplasts, plant tissues, plant cell tissue cultures, plant calli, plant clumps, and the like. As used herein, “shoot” refers to the above ground parts including the leaves and stems. Further, as used herein, “plant cell” refers to a structural and physiological unit of the plant, which comprises a cell wall and also may refer to a protoplast. A plant cell can be in the form of an isolated single cell or can be a cultured cell or can be a part of a higher-organized unit such as, for example, a plant tissue or a plant organ.
In some embodiments, when a plant part or plant cell is stably transformed, it can then be used to regenerate a stably transformed plant comprising one or more modifications as described herein using the compositions and methods of the invention.
Non-limiting examples of plants useful with the present invention include turf grasses (e.g., bluegrass, bentgrass, ryegrass, fescue), feather reed grass, tufted hair grass, miscanthus, arundo, switchgrass, vegetable crops, including artichokes, kohlrabi, arugula, leeks, asparagus, lettuce (e.g., head, leaf, romaine), malanga, melons (e.g., muskmelon, watermelon, crenshaw, honeydew, cantaloupe), cole crops (e.g., brussels sprouts, cabbage, cauliflower, broccoli, collards, kale, Chinese cabbage, bok choy), cardoni, carrots, napa, okra, onions, celery, parsley, chick peas, parsnips, chicory, peppers, potatoes, cucurbits (e.g., marrow, cucumber, zucchini, squash, pumpkin, honeydew melon, watermelon, cantaloupe), radishes, dry bulb onions, rutabaga, eggplant, salsify, escarole, shallots, endive, garlic, spinach, green onions, squash, greens, beet (sugar beet and fodder beet), sweet potatoes, chard, horseradish, tomatoes, turnips, and spices; a fruit crop such as apples, apricots, cherries, nectarines, peaches, pears, plums, prunes, cherry, quince, fig, nuts (e.g., chestnuts, pecans, pistachios, hazelnuts, pistachios, peanuts, walnuts, macadamia nuts, almonds, and the like), citrus (e.g., clementine, kumquat, orange, grapefruit, tangerine, mandarin, lemon, lime, and the like), blueberries, black raspberries, boysenberries, cranberries, currants, gooseberries, loganberries, raspberries, strawberries, blackberries, grapes (wine and table), avocados, bananas, kiwi, persimmons, pomegranate, pineapple, tropical fruits, pomes, melon, mango, papaya, and lychee, a field crop plant such as clover, alfalfa, timothy, evening primrose, meadow foam, corn/maize (field, sweet, popcorn), hops, jojoba, buckwheat, safflower, quinoa, wheat, rice, barley, rye, millet, sorghum, oats, triticale, sorghum, tobacco, kapok, a leguminous plant (beans (e.g., green and dried), lentils, peas, soybeans), an oil plant (rape, canola, mustard, poppy, olive, sunflower, coconut, castor oil plant, cocoa bean, groundnut, oil palm), duckweed, Arabidopsis, a fiber plant (cotton, flax, hemp, jute), Cannabis (e.g., Cannabis sativa, Cannabis indica, and Cannabis ruderalis), lauraceae (cinnamon, camphor), or a plant such as coffee, sugar cane, tea, and natural rubber plants; and/or a bedding plant such as a flowering plant, a cactus, a succulent and/or an ornamental plant (e.g., roses, tulips, violets), as well as trees such as forest trees (broad-leaved trees and evergreens, such as conifers; e.g., elm, ash, oak, maple, fir, spruce, cedar, pine, birch, cypress, eucalyptus, willow), as well as shrubs and other nursery stock. In some embodiments, the nucleic acid constructs of the invention and/or expression cassettes and/or vectors encoding the same may be used to modify maize, soybean, wheat, canola, rice, cotton, tomato, pepper, sunflower, raspberry, blackberry, black raspberry and/or cherry.
In some embodiments, the invention provides cells (e.g., plant cells, animal cells, bacterial cells, archaeon cells, and the like) comprising one or more polypeptide(s), polynucleotide(s), guide nucleic acid(s), nucleic acid construct(s), expression cassette(s), and/or vector(s) of the invention.
The present invention further comprises a kit or kits to carry out the methods of this invention. A kit of this invention can comprise reagents, buffers, and apparatus for mixing, measuring, sorting, labeling, etc., as well as instructions and the like as would be appropriate for modifying a target nucleic acid.
In some embodiments, the invention provides a kit comprising one or more polypeptide(s) of the invention, one or more polynucleotide(s) of the invention (e.g., nucleic acid constructs), and/or one or more expression cassette(s), vector(s), and/or cell(s) or the invention, with optional instructions for the use thereof. In some embodiments, a kit may comprise a CRISPR-Cas guide nucleic acid (corresponding to a CRISPR-Cas effector protein of the invention) and/or an expression cassette, cell, and/or vector comprising the same. In some embodiments, a guide nucleic acid may be provided on the same expression cassette and/or vector as one or more nucleic acid constructs of the invention. In some embodiments, the guide nucleic acid may be provided on a separate expression cassette or vector from that comprising the one or more nucleic acid constructs of the invention.
In some embodiments, kits are provided comprising a nucleic acid construct comprising (a) a polynucleotide(s) as provided herein and (b) a promoter that drives expression of the polynucleotide(s) of (a). In some embodiments, the kit may further comprise a nucleic acid construct encoding a guide nucleic acid, wherein the construct comprises a cloning site for cloning of a nucleic acid sequence identical or complementary to a target nucleic acid sequence into backbone of the guide nucleic acid.
In some embodiments, a nucleic acid construct of the invention may be an mRNA that may encode one or more introns within the encoded polynucleotide(s). In some embodiments, the nucleic acid constructs of the invention and/or an expression cassettes and/or vectors comprising the same, may further encode one or more selectable markers useful for identifying transformants (e.g., a nucleic acid encoding an antibiotic resistance gene, herbicide resistance gene, and the like).
A polypeptide, polynucleotide, nucleic acid construct, expression cassette, vector, composition, kit, system and/or cell of the present invention may comprise all or a portion of a sequence of one or more of SEQ ID NOs:1-83. In some embodiments, a polypeptide, polynucleotide, nucleic acid construct, expression cassette, vector, composition, kit, system and/or cell of the present invention may comprise at least about 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or more consecutive amino acids of a sequence of one or more of SEQ ID NOs:1-83.
The invention will now be described with reference to the following examples. It should be appreciated that these examples are not intended to limit the scope of the claims to the invention, but are rather intended to be exemplary of certain embodiments. Any variations in the exemplified methods that occur to the skilled artisan are intended to fall within the scope of the invention.
Prime Editing is a genome editing method that uses reverse transcriptase (RT) with non-template strand nickase Cas9 (H840A). In Prime Editing, guide RNA is fused to a sequence complementary to the target site which allows RT-mediated DNA polymerization. Prime Editing window extends several bases downstream of protospacer, and the pegRNA that contains the desired edit and the template may contain long RNA sequences complementary to the genomic loci. Optimization of pegRNA is one of the key determinants of successful Prime Editing. The present invention will be useful because pegRNA has been shown to display varying levels of efficiency depending on their length and sequence composition, which is hard to predict. As pegRNA contains sequences in the target genomic loci outside of the protospacer, previous art, which only contains the protospacer sequence in the reporter module, cannot be used to optimize pegRNA designs.
In this experiment, two different target sequences were tested: DNMT1 and RNF2. These are endogenous genes within human cells. The two different target sequences were separately introduced upstream of mCherry protein as a P2A protein fusion, so that editing at those loci is functionally linked to fluorescence.
Both target sequences were modified to contain a single stop codon in the Prime Editing window when translated as a fusion to a downstream mCherry protein. Upon successful Prime Editing, the stop codon will be replaced by an amino acid residue, enabling translation of downstream mCherry. One can use this reporter system to optimize pegRNA designs.
The following plasmids were transfected into HEK293T cells:
(1) Nucleic acid reporter plasmid that contains target sequence (60 base sequence of endogenous gene (DNMT1 or RNF2) that contains spacer sequence in the middle) as a protein coding sequence at the N-terminus of mCherry,
(2) Plasmid expressing Cas9 Prime Editor (PE2) (Anzalone et al, 2019), and
(3) Plasmid expressing pegRNA targeting the ‘target sequence’ and whose edit is designed to remove a stop codon designed into the ‘target sequence’ via reverse-transcriptase-mediated Prime Editing.
After a three-day incubation, the fluorescence level of the cells was analyzed using flow cytometry and the results are provided in
Similar to Example 1, a target sequence (an endogenous gene sequence within human cells) was inserted upstream of a mCherry sequence. A single base insertion or deletion was introduced in the target sequence, which introduced a frameshift mutation that prevents translation of mCherry downstream. The reporter construct was then targeted with Cas9 and a guide RNA at the protospacer within the target sequence. The desired outcome was that Cas9 mediated cleavage and the resulting DNA repair would generate a converse insertion or deletion that may restore the open reading frame that includes functional mCherry.
The following plasmids were transfected into HEK293T cells:
(1) Nucleic acid reporter plasmid that contains target sequence (60 base sequence of endogenous gene (RUNX1) that contains spacer sequence in the middle) as a protein coding sequence at the N-terminus of mCherry,
(2) Plasmid expressing Cas9 nuclease, and
(3) Plasmid expressing a guide RNA targeting the ‘target sequence’.
After a three-day incubation, the fluorescence level of the cells was analyzed using flow cytometry and the results are provided in
Approximately 60 base pairs of a target sequence from Zea maize (corn) was inserted upstream of mCherry in frame of translation consistent with the diagram of
Various RNA extension sequences for reverse-transcriptase-mediated sequence correction of the stop codons were tested, as well as comparing an editing construct with and without reverse transcriptase. In addition, a sequence for stabilizing the RNA extension was evaluated. Specifically, four different RNA extension sequences (SEQ ID NOs:74-77) that could enable reverse transcriptase-mediated correction of stop codons in the reporter sequence and a crRNA without RNA extension sequence (SEQ ID NO:73) were tested with both LbCpf1 (i.e., LbCas12a as the editing enzyme without reverse transcriptase), and RT(5M)-LbCpf1-Brex27 (i.e., LbCas12a as the editing enzyme that is fused to a reverse transcriptase, SEQ ID NO:78). Compared to SEQ ID NO:73, SEQ ID NOs:74-75 each included a 100 base pair extension following the guide nucleic acid and SEQ ID NOs:76-77 each included a 113 base pair extension following the guide nucleic acid. Additionally, SEQ ID NOs:75 and 77 each included an RNA stabilizing sequence (SEQ ID NO:79) following their 100 or 113 base pair extension sequence.
As shown in
These results indicate that, when RT(5M)-LbCpf1-Brex27 was used, RNA extensions of 100 bp (SEQ ID NOs:74-75) or 113 bp (SEQ ID NOs:76-77) increased editing of the stop codons as demonstrated by comparing the RNA extended sequences (SEQ ID NOs:74-77) with the “no extension” control (SEQ ID NO:73). The reverse transcriptase construct data also suggests that the RNA stabilizing sequence in SEQ ID NO:75 was able to stabilize the RNA extension and result in an increase in fluorescence. This result was not observed with the RNA stabilizing sequence in SEQ ID NO:77. In addition, inclusion of reverse transcriptase increased the editing efficiency of the editing construct overall since the fluorescence observed with RT(5M)-LbCpf1-Brex27 was higher than the fluorescence obtained with LbCfp1, which did not include reverse transcriptase. This demonstrates that RNA sequence dependent activity is present with RT(5M)-LbCpf1-Brex27 and not with LbCfp1 without reverse transcriptase.
The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. The invention is defined by the following claims, with equivalents of the claims to be included therein.
| Number | Date | Country | |
|---|---|---|---|
| 63210151 | Jun 2021 | US |
