Patent Application
20220049273
The instant application contains a Sequence Listing which has been submitted electronically in ASCII format and is hereby incorporated by reference in its entirety. Said ASCII copy, created on Feb. 27, 2020, is named A2186-7015WO_SL.txt and is 1,436,701 bytes in size.
The present disclosure relates to novel CRISPR-Cas system compositions and methods of using the compositions, for example, nucleic acid targeting.
Recent application of advances in genome sequencing technologies and analysis have yielded significant insights into the genetic underpinning of biological activities in many diverse areas of nature, ranging from prokaryotic biosynthetic pathways to human pathologies. To fully understand and evaluate the vast quantities of information produced by genetic sequencing technologies, equivalent increases in the scale, efficacy, and ease of technologies for genome and epigenome manipulation are needed. These novel genome and epigenome engineering technologies will accelerate the development of novel applications in numerous areas, including biotechnology, agriculture, and human therapeutics.
Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and the CRISPR-associated (Cas) genes, collectively known as the CRISPR-Cas or CRISPR/Cas systems, are currently understood to provide immunity to bacteria and archaea against phage infection. The CRISPR-Cas systems of prokaryotic adaptive immunity are an extremely, diverse group of proteins effectors, non-coding elements, as well as loci architectures, some examples of which have been engineered and adapted to produce important biotechnologies.
The components of the system involved in host defense include one or more effector proteins capable of modifying DNA or RNA and an RNA guide element that is responsible to targeting these protein activities to a specific sequence on the phage DNA or RNA. The RNA guide is composed of a CRISPR RNA (crRNA) and may require an additional trans-activating RNA (tracrRNA) to enable targeted nucleic acid manipulation by the effector protein(s). The crRNA consists of a direct repeat responsible for protein binding to the crRNA and a spacer sequence that is complementary to the desired nucleic acid target sequence. CRISPR-Cas systems can be reprogrammed to target alternative DNA or RNA targets by modifying the spacer sequence of the crRNA.
CRISPR-Cas systems can be broadly classified into two classes: Class 1 systems are composed of multiple effector proteins that together form a complex around a crRNA, and Class 2 systems consist of a single effector protein that complexes with the crRNA to target DNA or RNA substrates. The single-subunit effector composition of the Class 2 systems provides a simpler component set for engineering and application translation and have thus far been an important source of programmable effectors. Thus, the discovery, engineering, and optimization of novel Class 2 systems may lead to widespread and powerful programmable technologies for genome engineering and beyond.
The characterization and engineering of Class 2 CRISPR-Cas systems, exemplified by CRISPR-Cas9, have paved the way for a diverse array of biotechnology applications in genome editing and beyond. For example, the effector proteins Cas12a (Cpf1) and Cas13a (C2c2) possess non-target-specific “collateral” single-stranded-nuclease cleavage activities, which may be harnessed to create novel diagnostics, methods, and other applications. Nevertheless, there remains a need for additional programmable effectors and systems for modifying nucleic acids and polynucleotides (i.e., DNA, RNA, or any hybrid, derivative, or modification) beyond the current CRISPR-Cas systems that enable novel applications through their unique properties.
It is against the above background that the present invention provides certain advantages and advancements over the prior art.
Although this invention disclosed herein is not limited to specific advantages or functionalities, the invention provides a composition comprising a CRISPR-Cas effector protein or a nucleic acid encoding the CRISPR-Cas effector protein, wherein the CRISPR-Cas effector protein has at least 80% (e.g., 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%) identity to an amino acid sequence set forth in any one of SEQ ID NOs: 1057-1066.
In one aspect of the composition, the CRISPR-Cas effector protein has an amino acid sequence set forth in any one of SEQ ID NOs: 1057-1066.
The invention further provides a composition comprising a CRISPR-Cas effector protein or a nucleic acid encoding the CRISPR-Cas effector protein, wherein the CRISPR-Cas effector protein comprises a mutation in a RuvC motif.
In one aspect of a composition of invention, the CRISPR-Cas effector protein comprises a mutation in a catalytic residue of a RuvC motif.
In one aspect of a composition of invention, the RuvC motif is a RuvC I, RuvC II, and/or RuvC III motif.
In one aspect of a composition of invention, the CRISPR-Cas effector protein comprises at least 10% (e.g., 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%) less nuclease activity than a reference composition.
In one aspect of a composition of invention, the CRISPR-Cas effector protein lacks nuclease activity.
In one aspect of a composition of invention, the CRISPR-Cas effector protein comprises at least 10% (e.g., 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100%) greater nuclease activity than a reference composition.
In one aspect of a composition of invention, the composition further comprises an RNA guide or a nucleic acid encoding the RNA guide, wherein the RNA guide comprises a direct repeat sequence and a spacer sequence, wherein the CRISPR-Cas effector protein binds to the RNA guide, and wherein the spacer sequence binds to a target nucleic acid.
In one aspect of a composition of invention, the spacer sequence comprises between 15 and 24 nucleotides in length. In one aspect of a composition of invention, the spacer sequence comprises between 16 and 22 nucleotides in length.
In one aspect of a composition of invention, the target nucleic acid comprises a sequence complementary to a nucleotide sequence in the spacer sequence.
In one aspect of a composition of invention, the CRISPR-Cas effector protein recognizes a protospacer adjacent motif (PAM) sequence in the target nucleic acid, wherein the PAM sequence comprises a nucleotide sequence set forth as 5′-TTN-3′ or 5′-YTN-3′, wherein N is any nucleotide and Y is cytosine or thymine.
In one aspect of a composition of invention, the target nucleic acid is DNA. In one aspect of a composition of invention, the target nucleic acid is supercoiled (e.g., plasmid) DNA. In one aspect of a composition of invention, the CRISPR-Cas effector protein further comprises at least one nuclear localization signal (NLS), at least one nuclear export signal (NES), or at least one NLS and at least one NES.
In one aspect of a composition of invention, the nucleic acid encoding the CRISPR-Cas effector protein is codon-optimized for expression in a cell.
In one aspect of a composition of invention, the nucleic acid encoding the CRISPR-Cas effector protein is operably linked to a promoter.
In one aspect of a composition of invention, the nucleic acid encoding the CRISPR-Cas effector protein is in a vector. In one aspect of a composition of invention, the vector comprises a retroviral vector, a lentiviral vector, a phage vector, an adenoviral vector, an adeno-associated vector, or a herpes simplex vector.
In one aspect of a composition of invention, the composition is present in a delivery system comprising a nanoparticle, a liposome, an exosome, a microvesicle, or a gene-gun.
The invention further provides a cell comprising a composition of the invention. In one aspect of the cell, the cell is a eukaryotic cell. In one aspect of the cell, the cell is a prokaryotic cell.
The invention further provides a method of expressing a composition of the invention, wherein the method comprises providing a composition of the invention and delivering the composition to the cell.
The present disclosure further provides non-naturally-occurring, engineered systems and compositions for new single-effector Class 2 CRISPR-Cas systems, together with methods for computational identification of new CRISPR-Cas systems from genomic databases, together with the development of the natural loci into engineered systems, and experimental validation and application translation. These new effectors are divergent in sequence to orthologs and homologs of existing Class 2 CRISPR effectors, and also have unique domain organizations. They provide additional features that include, but are not limited to, 1) novel DNA/RNA editing properties and control mechanisms, 2) smaller size for greater versatility in delivery strategies, 3) genotype triggered cellular processes such as cell death, and 4) programmable RNA-guided DNA insertion, excision, and mobilization. Adding the novel DNA-targeting systems described herein to the toolbox of techniques for genome and epigenome manipulation enables broad applications for specific, programmed perturbations.
This disclosure relates to new CRISPR-Cas systems including newly discovered enzymes and other components used to create minimal systems that can be used in non-natural environments, e.g., in bacteria other than those in which the system was initially discovered or in mammalian cells.
As used herein, the term “catalytic residue” refers to an amino acid that activates catalysis. A catalytic residue is an amino acid that is involved (e.g., directly involved) in catalysis. In some embodiments, a catalytic residue is a histidine, an aspartic acid, or a glutamic acid residue.
The term “cleavage event,” as used herein, refers to a DNA break in a target nucleic acid created by a nuclease of a CRISPR-Cas system described herein. In some embodiments, the cleavage event is a double-stranded DNA break. In some embodiments, the cleavage event is a single-stranded DNA break.
The term “CRISPR-Cas system” as used herein refers to nucleic acids and/or proteins involved in the expression of, or directing the activity of, CRISPR-Cas effectors, including sequences encoding CRISPR-Cas effectors, RNA guides, and other sequences and transcripts from a CRISPR locus.
The term “CRISPR array” as used herein refers to the nucleic acid (e.g., DNA) segment that includes CRISPR repeats and spacers, starting with the first nucleotide of the first CRISPR repeat and ending with the last nucleotide of the last (terminal) CRISPR repeat. Typically, each spacer in a CRISPR array is located between two repeats. The term “CRISPR repeat,” or “CRISPR direct repeat,” or “direct repeat,” as used herein, refers to multiple short direct repeating sequences, which show very little or no sequence variation within a CRISPR array.
The term “CRISPR RNA” or “crRNA” as used herein refers to an RNA molecule comprising a guide sequence used by a CRISPR effector to specifically target a nucleic acid sequence. Typically, crRNAs contain a sequence that mediates target recognition and a sequence that forms a duplex with a tracrRNA. The crRNA: tracrRNA duplex binds to a CRISPR effector. The term “donor template nucleic acid,” as used herein refers to a nucleic acid molecule that can be used by one or more cellular proteins to alter the structure of a target nucleic acid after a CRISPR enzyme described herein has altered a target nucleic acid. In some embodiments, the donor template nucleic acid is a double-stranded nucleic acid. In some embodiments, the donor template nucleic acid is a single-stranded nucleic acid. In some embodiments, the donor template nucleic acid is linear. In some embodiments, the donor template nucleic acid is circular (e.g., a plasmid). In some embodiments, the donor template nucleic acid is an exogenous nucleic acid molecule. In some embodiments, the donor template nucleic acid is an endogenous nucleic acid molecule (e.g., a chromosome).
The term “CRISPR-Cas effector,” “CRISPR effector,” “effector,” “CRISPR-associated protein,” or “CRISPR enzyme” as used herein refers to a protein that carries out an enzymatic activity or that binds to a target site on a nucleic acid specified by an RNA guide. In some embodiments, a CRISPR effector is a nuclease. In some embodiments, a CRISPR effector has endonuclease activity, nickase activity, exonuclease activity, and/or excision activity.
As used herein, the terms “domain” and “protein domain” refer to a distinct functional and/or structural unit of a protein. In some embodiments, a domain may comprise a conserved amino acid sequence.
As used herein, the term “enzymatic activity” refers to the catalytic ability of an enzyme. For example, enzymatic activity may include nuclease activity.
As used herein, the terms “engineered,” “genetically-engineered,” “genetically-modified,” “recombinant,” and “modified” are used interchangeably and indicate intentional human manipulation to create, or cause a change in, a sequence, combination of sequences, or composition such that the sequence, combination of sequences, or composition does not exist in nature. In some embodiments, a composition of the invention is a genetically-engineered composition.
As used herein, the term “nuclease” refers to an enzyme capable of cleaving a phosphodiester bond. A nuclease hydrolyzes phosphodiester bonds in a nucleic acid backbone.
As used herein the term “operably linked” refers to nucleic acid sequences or amino acid sequences placed into a functional relationship with one another. For instance, a promoter or enhancer is operably linked to a coding sequence if it affects the modulation of the transcription of the coding sequence. Operably linked DNA sequences encoding regulatory sequences are typically contiguous to the coding sequence. However, enhancers can be functional when separated from a promoter, e.g., by up to several kilobases or more. Accordingly, some nucleic acid molecules may be operably linked, but not contiguous.
As used herein, the terms “protospacer adjacent motif” and “PAM sequence” refer to a sequence located near or adjacent to a target sequence. As used herein, a PAM sequence is required for cleavage by a nuclease described herein.
As used herein, the terms “parent,” “nuclease parent,” and “parent sequence” refer to a nuclease to which an alteration is made to produce a variant nuclease of the present invention.
In some embodiments, the parent is a nuclease having an identical amino acid sequence of the variant at one or more of specified positions. The parent may be a naturally occurring (wild-type) polypeptide. In a particular embodiment, the parent is a nuclease with at least 60%, at least 61%, at least 62%, at least 63%, at least 64%, at least 65%, at least 70%, at least 72%, at least 73%, at least 74%, at least 75%, at least 80%, at least 81%, at least 82%, at least 83%, at least 84%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, at least 99% or 100% identity to a polypeptide of SEQ ID NO: 1 or SEQ ID NO: 20.
As used herein, the terms “reference composition,” “reference sequence,” and “reference” refer to a control, such as a negative control or a parent (e.g., a parent sequence, a parent protein, or a wild-type protein). In some embodiments, a reference sequence is set forth in SEQ ID NO: 1 or SEQ ID NO: 20.
As used herein, the terms “RNA guide” or “RNA guide sequence” refer to a molecule that recognizes (e.g., binds to) a target nucleic acid. An RNA guide may be designed to be complementary to a specific nucleic acid sequence. An RNA guide comprises a spacer sequence and a direct repeat (DR) sequence. The terms CRISPR RNA (crRNA), pre-crRNA, mature crRNA, and CRISPR array are also used herein to refer to an RNA guide.
As used herein, the term “RuvC domain” refers to a conserved domain or motif of amino acids having nuclease (e.g., endonuclease) activity. As used herein, a protein having a split RuvC domain refers to a protein having two or more RuvC motifs, at sequentially disparate sites within a sequence, that interact in a tertiary structure to form a RuvC domain.
As used herein, the terms “target nucleic acid” and “target sequence” refer to a nucleic acid that is specifically bound by a targeting moiety. In some embodiments, the spacer sequence of an RNA guide binds to the target nucleic acid.
As used herein, the terms “trans-activating crRNA” and “tracrRNA” refer to an RNA molecule involved in or required for the binding of an RNA guide to a target nucleic acid.
As used herein, the terms “variant” and “mutant” refer to a protein comprising an alteration, e.g., a substitution, insertion, deletion and/or fusion, at one or more (or one or several) positions, compared to its parent sequence. In some embodiments, the variant is a CRISPR-Cas effector protein variant. In some embodiments, the variant has an amino acid sequence set forth in any one of SEQ ID NOs: 1057-1066.
As used herein, the term “subject,” refers to any mammals, including, without limitation, humans and other primates, including rhesus macaques, chimpanzees and other monkey and ape species; farm animals, such as cattle, sheep, pigs, goats, and horses; domestic mammals, such as dogs and cats; laboratory animals, including rabbits, mice, rats, and guinea pigs; as well as birds, including domestic, wild, and game birds, such as chickens, turkeys, ducks, and geese; and the like. The term includes adult, young, and newborn individuals as well as male and female subjects. In some embodiments, a host cell is derived from a subject (e.g., stem cells, progenitor cells, or tissue-specific cells). In some embodiments, the subject is a non-human subject.
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. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.
Other features and advantages of the invention will be apparent from the following detailed description, and from the claims.
The present disclosure relates to novel compositions comprising CRISPR-Cas effector proteins and methods of use thereof. In some aspects, a composition comprising a CRISPR-Cas effector protein having one or more characteristics is described herein. In some aspects, a method of producing the composition is described. In some aspects, a method of delivering the composition is described.
In one aspect, the disclosure provides Class 2 CRISPR-Cas systems referred to herein as CLUST.018837. These Class 2 CRISPR-Cas systems contain an isolated CRISPR-associated protein having a RuvC domain.
In some embodiments, the CRISPR-associated protein and the RNA guide form a “binary” complex that may include other components. The binary complex is activated upon binding to a nucleic acid substrate that is complementary to a spacer sequence in the RNA guide (i.e., a sequence-specific substrate or target nucleic acid). In some embodiments, the sequence-specific substrate is a double-stranded DNA. In some embodiments, the sequence-specific substrate is a single-stranded DNA. In some embodiments, the sequence-specific substrate is a single-stranded RNA. In some embodiments, the sequence-specific substrate is a double-stranded RNA. In some embodiments, the sequence-specificity requires a complete match of the spacer sequence in the RNA guide (e.g., crRNA) to the target substrate. In other embodiments, the sequence specificity requires a partial (contiguous or non-contiguous) match of the spacer sequence in the RNA guide (e.g., crRNA) to the target substrate.
In some embodiments, the binary complex becomes activated upon binding to the target substrate. In some embodiments, the activated complex exhibits “multiple turnover” activity, whereby upon acting on (e.g., cleaving) the target substrate the activated complex remains in an activated state. In some embodiments, the activated binary complex exhibits “single turnover” activity, whereby upon acting on the target substrate the binary complex reverts to an inactive state. In some embodiments, the activated binary complex exhibits non-specific (i.e., “collateral”) cleavage activity whereby the complex cleaves non-target nucleic acids. In some embodiments, the non-target nucleic acid is a DNA (e.g., a single-stranded or a double-stranded DNA). In some embodiments, the non-target nucleic acid is an RNA (e.g., a single-stranded or a double-stranded RNA).
In some embodiments, the composition of the present invention includes a CRISPR-Cas effector protein described herein. A nucleic acid sequence encoding the CRISPR-Cas effector protein described herein may be substantially identical to a reference nucleic acid sequence if the nucleic acid encoding the CRISPR-Cas effector protein comprises a sequence having least about 60%, least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or at least about 99.5% sequence identity to the reference nucleic acid sequence. The percent identity between two such nucleic acids can be determined manually by inspection of the two optimally aligned nucleic acid sequences or by using software programs or algorithms (e.g., BLAST, ALIGN, CLUSTAL) using standard parameters. One indication that two nucleic acid sequences are substantially identical is that the two nucleic acid molecules hybridize to each other under stringent conditions (e.g., within a range of medium to high stringency).
In some embodiments, the CRISPR-Cas effector protein is encoded by a nucleic acid sequence having at least about 60%, least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or at least about 99.5% sequence identity to a reference nucleic acid sequence.
The CRISPR-Cas effector protein described herein may substantially identical to a reference polypeptide if the CRISPR-Cas effector protein comprises an amino acid sequence having at least about 60%, least about 65%, least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or at least about 99.5% sequence identity to the amino acid sequence of the reference polypeptide. The percent identity between two such polypeptides can be determined manually by inspection of the two optimally aligned polypeptide sequences or by using software programs or algorithms (e.g., BLAST, ALIGN, CLUSTAL) using standard parameters. One indication that two polypeptides are substantially identical is that the first polypeptide is immunologically cross-reactive with the second polypeptide. Typically, polypeptides that differ by conservative amino acid substitutions are immunologically cross-reactive. Thus, a polypeptide is substantially identical to a second polypeptide, for example, where the two peptides differ only by a conservative amino acid substitution or one or more conservative amino acid substitutions.
In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1. In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having greater than 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1.
In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 20. In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having greater than 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 20.
In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1057. In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having greater than 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1057.
In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1058. In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having greater than 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1058.
In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1059. In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having greater than 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1059.
In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1060. In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having greater than 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1060.
In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1061. In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having greater than 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1061.
In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1062. In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having greater than 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1062.
In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1063. In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having greater than 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1063.
In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1064. In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having greater than 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1064.
In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1065. In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having greater than 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1065.
In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1066. In some embodiments, the CRISPR-Cas effector protein of the present invention comprises a polypeptide sequence having greater than 50, 60, 65, 70, 75, 80, 85, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 100% identity to SEQ ID NO: 1066.
In some embodiments, the CRISPR-Cas effector protein of the present invention is a CRISPR-Cas effector protein having a specified degree of amino acid sequence identity to one or more reference polypeptides, e.g., at least 60%, at least 65%, at least 70%, at least 75%, at least 80%, at least 85%, at least 90%, at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, or even at least 99% sequence identity to the amino acid sequence of SEQ ID NO: 1 or SEQ ID NO: 20. Homology or identity can be determined by amino acid sequence alignment, e.g., using a program such as BLAST, ALIGN, or CLUSTAL, as described herein.
In some embodiments, the CRISPR-Cas effector protein comprises a protein with an amino acid sequence with at least about 60%, least about 65%, at least about 70%, at least about 75%, at least about 80%, at least about 85%, at least about 90%, at least about 91%, at least about 92%, at least about 93%, at least about 94%, at least about 95%, at least about 96%, at least about 97%, at least about 98%, at least about 99%, or at least about 99.5% sequence identity to the reference amino acid sequence.
Also provided is a CRISPR-Cas effector protein of the present invention and comprising an amino acid sequence which differs from the amino acid sequences of any one of SEQ ID NO: 1, SEQ ID NO: 20, SEQ ID NO: 1057, SEQ ID NO: 1058, SEQ ID NO: 1059, SEQ ID NO: 1060, SEQ ID NO: 1061, SEQ ID NO: 1062, SEQ ID NO: 1063, SEQ ID NO: 1064, SEQ ID NO: 1065, or SEQ ID NO: 1066 by no more than 50, no more than 40, no more than 35, no more than 30, no more than 25, no more than 20, no more than 19, no more than 18, no more than 17, no more than 16, no more than 15, no more than 14, no more than 13, no more than 12, no more than 11, no more than 10, no more than 9, no more than 8, no more than 7, no more than 6, no more than 5, no more than 4, no more than 3, no more than 2, or no more than 1 amino acid residue(s), when aligned using any of the previously described alignment methods.
In some embodiments, the CRISPR-Cas effector protein comprises a RuvC domain. In some embodiments, the CRISPR-Cas effector protein comprises a split RuvC domain or two or more (e.g., 3) partial RuvC domains. For example, the CRISPR-Cas effector protein comprises RuvC motifs that are not contiguous with respect to the primary amino acid sequence of the CRISPR-Cas effector protein but form a RuvC domain once the protein folds. In some embodiments, the catalytic residue of a RuvC motif is a histidine, glutamic acid residue, and/or an aspartic acid residue, including H297, D303, E311, E504, or D559 according to the numbering of SEQ ID NO: 1 or H300, D306, E332, E516, or D569 according to the numbering of SEQ ID NO: 20.
In some embodiments, the invention includes an isolated, recombinant, substantially pure, or non-naturally occurring CRISPR-Cas effector protein comprising a RuvC domain, wherein the CRISPR-Cas effector protein has enzymatic activity, e.g., nuclease or endonuclease activity, wherein the CRISPR-Cas effector protein comprises an amino acid sequence having at least about 60%, 65%, 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to SEQ ID NO: 1, SEQ ID NO: 20, SEQ ID NO: 1057, SEQ ID NO: 1058, SEQ ID NO: 1059, SEQ ID NO: 1060, SEQ ID NO: 1061, SEQ ID NO: 1062, SEQ ID NO: 1063, SEQ ID NO: 1064, SEQ ID NO: 1065, or SEQ ID NO: 1066.
In some embodiments, the invention includes a CRISPR-Cas effector protein comprising a mutated RuvC domain, wherein the CRISPR-Cas effector protein has modified enzymatic activity, e.g., nuclease or endonuclease activity, wherein the CRISPR-Cas effector protein comprises an amino acid sequence having at least about 60%, 65%, 70%, 75%, 80%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100% sequence identity to SEQ ID NO: 1057, SEQ ID NO: 1058, SEQ ID NO: 1059, SEQ ID NO: 1060, SEQ ID NO: 1061, SEQ ID NO: 1062, SEQ ID NO: 1063, SEQ ID NO: 1064, SEQ ID NO: 1065, or SEQ ID NO: 1066.
Modified CRISPR Enzyme Activity
In some embodiments, the present invention includes variants of the nuclease described herein. In some embodiments, the nuclease described herein can be mutated at one or more amino acid residues to modify one or more functional activities. For example, in some embodiments, the nuclease is mutated at one or more amino acid residues to modify its nuclease activity (e.g., cleavage activity). For example, in some embodiments, the nuclease may comprise one or more mutations that increase the ability of the nuclease to cleave a target nucleic acid. In some embodiments, the nuclease is mutated at one or more amino acid residues to modify its ability to functionally associate with an RNA guide. In some embodiments, the nuclease is mutated at one or more amino acid residues to modify its ability to functionally associate with a target nucleic acid.
Where the CRISPR enzymes described herein have nuclease activity, the CRISPR enzymes can be modified to have diminished nuclease activity, e.g., nuclease inactivation of at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 97%, or 100% as compared with the wild type CRISPR enzymes. The nuclease activity can be diminished by several methods known in the art, e.g., introducing mutations into the nuclease domains of the proteins. In some embodiments, catalytic residues for the nuclease activities are identified, and these amino acid residues can be substituted by different amino acid residues (e.g., glycine or alanine) to diminish the nuclease activity. In some embodiments, a catalytic residue of a RuvC motif (RuvC I, RuvC II, or RuvC III) is mutated to decrease or inactivate nuclease activity. See, e.g.,
Where the CRISPR enzymes described herein have nuclease activity, the CRISPR enzymes can be modified to have increased nuclease activity, e.g., nuclease activation of at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, at least 95%, at least 97%, or 100% as compared with the wild type CRISPR enzymes. The nuclease activity can be increased by several methods known in the art, e.g., introducing mutations into the nuclease domains of the proteins. In some embodiments, catalytic residues for the nuclease activities are identified, and these amino acid residues can be substituted by different amino acid residues (e.g., glycine or alanine) to increase or activate the nuclease activity. See, e.g.,
As used herein, a “biologically active portion” is a portion that maintains the function (e.g. completely, partially, minimally) of the nuclease (e.g., a “minimal” or “core” domain). In some embodiments, a nuclease fusion protein is useful in the methods described herein. Accordingly, in some embodiments, a nucleic acid encoding the fusion nuclease is described herein. In some embodiments, all or a portion of one or more components of the nuclease fusion protein are encoded in a single nucleic acid sequence.
In some embodiments, a variant nuclease has a conservative or non-conservative amino acid substitution, deletion or addition. In some embodiments, the variant nuclease has a silent substitution, deletion or addition, or a conservative substitution, none of which alter the polypeptide activity of the present invention. Typical examples of the conservative substitution include substitution whereby one amino acid is exchanged for another, such as exchange among aliphatic amino acids Ala, Val, Lu and Ile, exchange between hydroxyl residues Ser and Thr, exchange between acidic residues Asp and Glu, substitution between amide residues Asn and Gln, exchange between basic residues Lys and Arg, and substitution between aromatic residues Phe and Tyr. In some embodiments, one or more residues of a nuclease disclosed herein are mutated to an Arg residue. In some embodiments, one or more residues of a nuclease disclosed herein are mutated to a Gly residue.
A variety of methods are known in the art that are suitable for generating modified polynucleotides that encode variant nucleases of the invention, including, but not limited to, for example, site-saturation mutagenesis, scanning mutagenesis, insertional mutagenesis, deletion mutagenesis, random mutagenesis, site-directed mutagenesis, and directed-evolution, as well as various other recombinatorial approaches. Methods for making modified polynucleotides and proteins (e.g., nucleases) include DNA shuffling methodologies, methods based on non-homologous recombination of genes, such as ITCHY (See, Ostermeier et al., 7:2139-44 [1999]), SCRACHY (See, Lutz et al. 98:11248-53 [2001]), SHIPREC (See, Sieber et al., 19:456-60 [2001]), and NRR (See, Bittker et al., 20:1024-9 [2001]; Bittker et al., 101:7011-6 [2004]), and methods that rely on the use of oligonucleotides to insert random and targeted mutations, deletions and/or insertions (See, Ness et al., 20:1251-5 [2002]; Coco et al., 20:1246-50 [2002]; Zha et al., 4:34-9 [2003]; Glaser et al., 149:3903-13 [1992]).
Generation of Fusion Proteins
Additionally, nuclease dead CRISPR enzymes, whether in their native form or with mutations to modulate their nuclease activity, can provide a foundation from which fusion proteins with additional functional proteins can be created. The nuclease dead CRISPR enzymes can comprise or be associated (e.g., via fusion protein, linker peptides, and “GS” linkers) with one or more functional domains. These functional domains can have various activities, e.g., methylase activity, demethylase activity, transcription activation activity, transcription repression activity, transcription release factor activity, histone modification activity, RNA cleavage activity, DNA cleavage activity, nucleic acid binding activity, and switch activity (e.g., light inducible). In some embodiments, the functional domains are Krüppel associated box (KRAB), VP64, VP16, FokI, P65, HSF1, MyoD1, and biotin-APEX.
The positioning of the one or more functional domains on the nuclease dead CRISPR enzymes is one that allows for correct spatial orientation for the functional domain to affect the target with the attributed functional effect. For example, if the functional domain is a transcription activator (e.g., VP16, VP64, or p65), the transcription activator is placed in a spatial orientation that allows it to affect the transcription of the target. Likewise, a transcription repressor is positioned to affect the transcription of the target, and a nuclease (e.g., FokI) is positioned to cleave or partially cleave the target. In some embodiments, the functional domain is positioned at the N-terminus of the CRISPR enzyme. In some embodiments, the functional domain is positioned at the C-terminus of the CRISPR enzyme. In some embodiments, the inactivated CRISPR enzyme is modified to comprise a first functional domain at the N-terminus and a second functional domain at the C-terminus.
The addition of functional domains to the CRISPR enzymes or onto other effector proteins in the complex may provide an ability for the CRISPR-Cas system to modify the physical DNA (e.g., methylation, etc.) or its regulation (e.g., transcriptional or repression) in situ.
Split Enzymes
The present disclosure also provides a split version of the CRISPR enzymes described herein. The split version of the CRISPR enzymes may be advantageous for delivery. In some embodiments, the CRISPR enzymes are split to two parts of the enzymes, which together substantially comprises a functioning CRISPR enzyme.
The split can be done in a way that the catalytic domain(s) are unaffected. The CRISPR enzymes may function as a nuclease or may be inactivated enzymes, which are essentially RNA-binding proteins with very little or no catalytic activity (e.g., due to mutation(s) in its catalytic domains).
In some embodiments, the nuclease lobe and α-helical lobe are expressed as separate polypeptides. Although the lobes do not interact on their own, the RNA guide recruits them into a ternary complex that recapitulates the activity of full-length CRISPR enzymes and catalyzes site-specific DNA cleavage. The use of a modified RNA guide abrogates split-enzyme activity by preventing dimerization, allowing for the development of an inducible dimerization system. The split enzyme is described, e.g., in Wright, Addison V., et al. “Rational design of a split-Cas9 enzyme complex,” Proc. Nat'l. Acad. Sci., 112.10 (2015): 2984-2989, which is incorporated herein by reference in its entirety.
In some embodiments, the split enzyme can be fused to a dimerization partner, e.g., by employing rapamycin sensitive dimerization domains. This allows the generation of a chemically inducible CRISPR enzyme for temporal control of CRISPR enzyme activity. The CRISPR enzymes can thus be rendered chemically inducible by being split into two fragments and rapamycin-sensitive dimerization domains can be used for controlled reassembly of the CRISPR enzymes.
The split point is typically designed in silico and cloned into the constructs. During this process, mutations can be introduced to the split enzyme and non-functional domains can be removed. In some embodiments, the two parts or fragments of the split CRISPR enzyme (i.e., the N-terminal and C-terminal fragments), can form a full CRISPR enzyme, comprising, e.g., at least 70%, at least 80%, at least 90%, at least 95%, or at least 99% of the sequence of the wild-type CRISPR enzyme.
Self-Activating or Inactivating Enzymes
The CRISPR enzymes described herein can be designed to be self-activating or self-inactivating. In some embodiments, the CRISPR enzymes are self-inactivating. For example, the target sequence can be introduced into the CRISPR enzyme coding constructs. Thus, the CRISPR enzymes can modify, e.g., cleave, the target sequence, as well as the construct encoding the enzyme thereby self-inactivating their expression. Methods of constructing a self-inactivating CRISPR-Cas system is described, e.g., in Epstein, Benjamin E., and David V. Schaffer. “Engineering a Self-Inactivating CRISPR-Cas System for AAV Vectors,” Mol. Ther., 24 (2016): S50, which is incorporated herein by reference in its entirety.
In some other embodiments, an additional RNA guide, expressed under the control of a weak promoter (e.g., 7SK promoter), can target the nucleic acid sequence encoding the CRISPR enzyme to prevent and/or block its expression (e.g., by preventing the transcription and/or translation of the nucleic acid). The transfection of cells with vectors expressing the CRISPR enzyme, and RNA guides that target the nucleic acid encoding the CRISPR enzyme can lead to efficient disruption of the nucleic acid encoding the CRISPR enzyme and decrease the levels of CRISPR enzyme, thereby limiting the genome editing activity.
In some embodiments, the genome editing activity of the CRISPR enzymes can be modulated through endogenous RNA signatures (e.g., miRNA) in mammalian cells. The CRISPR enzyme switch can be made by using a miRNA-complementary sequence in the 5′-UTR of mRNA encoding the CRISPR enzyme. The switches selectively and efficiently respond to miRNA in the target cells. Thus, the switches can differentially control the genome editing by sensing endogenous miRNA activities within a heterogeneous cell population. Therefore, the switch systems can provide a framework for cell-type selective genome editing and cell engineering based on intracellular miRNA information (Hirosawa, Moe et al. “Cell-type-specific genome editing with a microRNA-responsive CRISPR-Cas9 switch,” Nucl. Acids Res., 2017 Jul. 27; 45(13): e118).
Inducible CRISPR Enzymes
The CRISPR enzymes can be inducible, e.g., light inducible or chemically inducible. This mechanism allows for activation of the functional domain in the CRISPR enzymes. Light inducibility can be achieved by various methods known in the art, e.g., by designing a fusion complex wherein CRY2PHR/CIBN pairing is used in split CRISPR Enzymes (see, e.g., Konermann et al. “Optical control of mammalian endogenous transcription and epigenetic states,” Nature, 500.7463 (2013): 472). Chemical inducibility can be achieved, e.g., by designing a fusion complex wherein FKBP/FRB (FK506 binding protein/FKBP rapamycin binding domain) pairing is used in split CRISPR Enzymes. Rapamycin is required for forming the fusion complex, thereby activating the CRISPR enzymes (see, e.g., Zetsche, Volz, and Zhang, “A split-Cas9 architecture for inducible genome editing and transcription modulation,” Nature Biotech., 33.2 (2015): 139-142).
Furthermore, expression of the CRISPR enzymes can be modulated by inducible promoters, e.g., tetracycline or doxycycline controlled transcriptional activation (Tet-On and Tet-Off expression system), hormone inducible gene expression system (e.g., an ecdysone inducible gene expression system), and an arabinose-inducible gene expression system. When delivered as RNA, expression of the RNA targeting effector protein can be modulated via a riboswitch, which can sense a small molecule like tetracycline (see, e.g., Goldfless, Stephen J. et al. “Direct and specific chemical control of eukaryotic translation with a synthetic RNA-protein interaction,” Nuc. Acids Res., 40.9 (2012): e64-e64).
Various embodiments of inducible CRISPR enzymes and inducible CRISPR-Cas systems are described, e.g., in U.S. Pat. No. 8,871,445, US20160208243, and WO2016205764, each of which is incorporated herein by reference in its entirety.
Functional Mutations
Various mutations or modifications can be introduced into CRISPR enzymes as described herein to improve specificity and/or robustness. In some embodiments, the amino acid residues that recognize the Protospacer Adjacent Motif (PAM) are identified. The CRISPR enzymes described herein can be modified further to recognize different PAMs, e.g., by substituting the amino acid residues that recognize PAM with other amino acid residues. In some embodiments, the CRISPR enzymes can recognize a PAM, e.g., 5′-TTN-3′ or 5′-YTN-3′, wherein N is any nucleobase and Y is cytosine or thymine.
In some embodiments, at least one Nuclear Localization Signal (NLS) is attached to the nucleic acid sequences encoding the CRISPR enzyme. In some embodiments, at least one Nuclear Export Signal (NES) is attached to the nucleic acid sequences encoding the CRISPR enzyme. In a preferred embodiment a C-terminal and/or N-terminal NLS or NES is attached for optimal expression and nuclear targeting in eukaryotic cells, e.g., human cells.
In some embodiments, the CRISPR enzyme is mutated at one or more amino acid residues to alter its ability to functionally associate with an RNA guide. In some embodiments, the CRISPR enzyme is mutated at one or more amino acid residues to alter its ability to functionally associate with a target nucleic acid.
In some embodiments, the CRISPR enzymes described herein are capable of binding to or modifying a target nucleic acid molecule. In some embodiments, the CRISPR enzyme modifies both strands of the target nucleic acid molecule. However, in some embodiments, the CRISPR enzyme is mutated at one or more amino acid residues to alter its nucleic acid manipulation activity. For example, in some embodiments, the CRISPR enzyme may comprise one or more mutations which render the enzyme incapable of cleaving a target nucleic acid. In other embodiments, the CRISPR enzyme may comprise one or more mutations such that the enzyme is capable of cleaving a single strand of the target nucleic acid (i.e., nickase activity). In some embodiments, the CRISPR enzyme is capable of cleaving the strand of the target nucleic acid that is complementary to the strand to which the RNA guide hybridizes. In some embodiments, the CRISPR enzyme is capable of cleaving the strand of the target nucleic acid to which the RNA guide hybridizes.
In some embodiments, a CRISPR enzyme described herein may be engineered to comprise a deletion in one or more amino acid residues to reduce the size of the enzyme while retaining one or more desired functional activities (e.g., nuclease activity and the ability to interact functionally with an RNA guide). The truncated CRISPR enzyme may be advantageously used in combination with delivery systems having load limitations.
Nucleic Acids Encoding the CRISPR-Associated Proteins
Nucleic acids encoding the proteins (e.g., a CRISPR-associated protein) and RNA guides (e.g., a crRNA) described herein are also provided. In some embodiments, the nucleic acid is a synthetic nucleic acid. In some embodiments, the nucleic acid is a DNA molecule. In some embodiments, the nucleic acid is an RNA molecule (e.g., an mRNA molecule). In some embodiments, the nucleic acid is an mRNA. In some embodiments, the mRNA is capped, polyadenylated, substituted with 5-methylcytidine, substituted with pseudouridine, or a combination thereof. In some embodiments, the nucleic acid (e.g., DNA) is operably-linked to a regulatory element (e.g., a promoter) to control the expression of the nucleic acid. In some embodiments, the promoter is a constitutive promoter. In some embodiments, the promoter is an inducible promoter. In some embodiments, the promoter is a cell-specific promoter. In some embodiments, the promoter is an organism-specific promoter. Suitable promoters are known in the art and include, for example, a pol I promoter, a pol II promoter, a pol III promoter, a T7 promoter, a U6 promoter, a H1 promoter, retroviral Rous sarcoma virus LTR promoter, a cytomegalovirus (CMV) promoter, a SV40 promoter, a dihydrofolate reductase promoter, and a β-actin promoter. For example, a U6 promoter can be used to regulate the expression of an RNA guide molecule described herein.
In some embodiments, the nucleic acids are modified, e.g., optimized, e.g., codon-optimized, for expression in a eukaryotic cell, e.g., a mammalian cell, such as a human cell.
In some embodiments, the nucleic acid(s) are present in a vector (e.g., a viral vector or a phage). The vectors can include one or more regulatory elements that allow for the propagation of the vector in a cell of interest (e.g., a bacterial cell or a mammalian cell). In some embodiments, the vector includes a nucleic acid encoding a single component of a CRISPR-associated (Cas) system described herein. In some embodiments, the vector includes multiple nucleic acids, each encoding a component of a CRISPR-associated (Cas) system described herein.
Spacer Lengths
The spacer length of RNA guides can range from about 15 to 50 nucleotides. In some embodiments, the spacer length of an RNA guide is at least 16 nucleotides, at least 17 nucleotides, at least 18 nucleotides, at least 19 nucleotides, at least 20 nucleotides, at least 21 nucleotides, or at least 22 nucleotides. In some embodiments, the spacer length is from 15 to 17 nucleotides, from 15 to 23 nucleotides, from 16 to 22 nucleotides, from 17 to 20 nucleotides, from 20 to 24 nucleotides (e.g., 20, 21, 22, 23, or 24 nucleotides), from 23 to 25 nucleotides (e.g., 23, 24, or 25 nucleotides), from 24 to 27 nucleotides, from 27 to 30 nucleotides, from 30 to 45 nucleotides (e.g., 30, 31, 32, 33, 34, 35, 40, or 45 nucleotides), from 30 or 35 to 40 nucleotides, from 41 to 45 nucleotides, from 45 to 50 nucleotides, or longer. In some embodiments, the direct repeat length of the RNA guide is at least 16 nucleotides, or is from 16 to 20 nucleotides (e.g., 16, 17, 18, 19, or 20 nucleotides). In some embodiments, the direct repeat length of the RNA guide is 19 nucleotides.
Exemplary RNA guide direct repeat sequences and effector protein pairs are provided in Table 3. In some embodiments, the RNA guide includes a direct repeat sequence comprising or consisting of a nucleic acid sequence listed in Table 3 (e.g., SEQ ID Nos: 27-47, 263-440).
The RNA guide sequences can be modified in a manner that allows for formation of the CRISPR complex and successful binding to the target, while at the same time not allowing for successful effector activity (i.e., without nuclease activity/without causing indels). These modified guide sequences are referred to as “dead guides” or “dead guide sequences.” These dead guides or dead guide sequences may be catalytically inactive or conformationally inactive with regard to nuclease activity. Dead guide sequences are typically shorter than respective guide sequences that result in active DNA modification. In some embodiments, dead guides are 5%, 10%, 20%, 30%, 40%, or 50%, shorter than respective RNA guides that have nuclease activity. Dead guide sequences of RNA guides can be from 13 to 15 nucleotides in length (e.g., 13, 14, or 15 nucleotides in length), from 15 to 19 nucleotides in length, or from 17 to 18 nucleotides in length (e.g., 17 nucleotides in length).
Thus, in one aspect, the disclosure provides non-naturally occurring or engineered CRISPR-Cas systems including a functional CRISPR enzyme as described herein, and an RNA guide wherein the RNA guide includes a dead guide sequence whereby the RNA guide is capable of hybridizing to a target sequence such that the CRISPR-Cas system is directed to a genomic locus of interest in a cell without detectable nucleic acid modification activity.
A detailed description of dead guides is described, e.g., in WO 2016094872, which is incorporated herein by reference in its entirety.
Inducible Guides
RNA guides can be generated as components of inducible systems. The inducible nature of the systems allows for spatiotemporal control of gene editing or gene expression. In some embodiments, the stimuli for the inducible systems include, e.g., electromagnetic radiation, sound energy, chemical energy, and/or thermal energy.
In some embodiments, the transcription of RNA guides can be modulated by inducible promoters, e.g., tetracycline or doxycycline controlled transcriptional activation (Tet-On and Tet-Off expression systems), hormone inducible gene expression systems (e.g., ecdysone inducible gene expression systems), and arabinose-inducible gene expression systems. Other examples of inducible systems include, e.g., small molecule two-hybrid transcription activations systems (FKBP, ABA, etc.), light inducible systems (Phytochrome, LOV domains, or cryptochrome), or Light Inducible Transcriptional Effector (LITE). These inducible systems are described, e.g., in WO 2016205764 and U.S. Pat. No. 8,795,965, both of which are incorporated herein by reference in their entirety.
Chemical Modifications
Chemical modifications can be applied to the RNA guide's phosphate backbone, sugar, and/or base. Backbone modifications such as phosphorothioates modify the charge on the phosphate backbone and aid in the delivery and nuclease resistance of the oligonucleotide (see, e.g., Eckstein, “Phosphorothioates, essential components of therapeutic oligonucleotides,” Nucl. Acid Ther., 24 (2014), pp. 374-387); modifications of sugars, such as 2′-O-methyl (2′-OMe), 2′-F, and locked nucleic acid (LNA), enhance both base pairing and nuclease resistance (see, e.g., Allerson et al. “Fully 2′-modified oligonucleotide duplexes with improved in vitro potency and stability compared to unmodified small interfering RNA,” J. Med. Chem., 48.4 (2005): 901-904). Chemically modified bases such as 2-thiouridine or N6-methyladenosine, among others, can allow for either stronger or weaker base pairing (see, e.g., Bramsen et al., “Development of therapeutic-grade small interfering RNAs by chemical engineering,” Front. Genet., 2012 Aug. 20; 3:154). Additionally, RNA is amenable to both 5′ and 3′ end conjugations with a variety of functional moieties including fluorescent dyes, polyethylene glycol, or proteins.
A wide variety of modifications can be applied to chemically synthesized RNA guide molecules. For example, modifying an oligonucleotide with a 2′-OMe to improve nuclease resistance can change the binding energy of Watson-Crick base pairing. Furthermore, a 2′-OMe modification can affect how the oligonucleotide interacts with transfection reagents, proteins or any other molecules in the cell. The effects of these modifications can be determined by empirical testing.
In some embodiments, the RNA guide includes one or more phosphorothioate modifications. In some embodiments, the RNA guide includes one or more locked nucleic acids for the purpose of enhancing base pairing and/or increasing nuclease resistance.
A summary of these chemical modifications can be found, e.g., in Kelley et al., “Versatility of chemically synthesized guide RNAs for CRISPR-Cas9 genome editing,” J. Biotechnol. 2016 Sep. 10; 233:74-83; WO 2016205764; and U.S. Pat. No. 8,795,965 B2; each which is incorporated by reference in its entirety.
Sequence Modifications
The sequences and the lengths of the RNA guides described herein can be optimized. In some embodiments, the optimized length of RNA guide can be determined by identifying the processed form of tracrRNA and/or crRNA, or by empirical length studies for guide RNAs, tracrRNAs, crRNAs, and the tracrRNA tetraloops.
The RNA guides can also include one or more aptamer sequences. Aptamers are oligonucleotide or peptide molecules that can bind to a specific target molecule. The aptamers can be specific to gene effectors, gene activators, or gene repressors. In some embodiments, the aptamers can be specific to a protein, which in turn is specific to and recruits/binds to specific gene effectors, gene activators, or gene repressors. The effectors, activators, or repressors can be present in the form of fusion proteins. In some embodiments, the RNA guide has two or more aptamer sequences that are specific to the same adaptor proteins. In some embodiments, the two or more aptamer sequences are specific to different adaptor proteins. The adaptor proteins can include, e.g., MS2, PP7, Qβ, F2, GA, fr, JP501, M12, R17, BZ13, JP34, JP500, KU1, M11, MX1, TW18, VK, SP, FI, ID2, NL95, TW19, AP205, φCb5, φCb8r, φCb12r, φCb23r, 7s, and PRR1. Accordingly, in some embodiments, the aptamer is selected from binding proteins specifically binding any one of the adaptor proteins as described herein. In some embodiments, the aptamer sequence is a MS2 loop. A detailed description of aptamers can be found, e.g., in Nowak et al., “Guide RNA engineering for versatile Cas9 functionality,” Nucl. Acid. Res., 2016 Nov. 16; 44(20):9555-9564; and WO 2016205764, which are incorporated herein by reference in their entirety.
Guide: Target Sequence Matching Requirements
In classic CRISPR-Cas systems, the degree of complementarity between a guide sequence and its corresponding target sequence can be about 50%, 60%, 75%, 80%, 85%, 90%, 95%, 97.5%, 99%, or 100%. In some embodiments, the degree of complementarity is 100%. The RNA guides can be about 5, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 35, 40, 45, 50, 75, or more nucleotides in length.
To reduce off-target interactions, e.g., to reduce the guide interacting with a target sequence having low complementarity, mutations can be introduced to the CRISPR-Cas systems so that the CRISPR-Cas systems can distinguish between target and off-target sequences that have greater than 80%, 85%, 90%, or 95% complementarity. In some embodiments, the degree of complementarity is from 80% to 95%, e.g., about 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, or 95% (for example, distinguishing between a target having 18 nucleotides from an off-target of 18 nucleotides having 1, 2, or 3 mismatches). Accordingly, in some embodiments, the degree of complementarity between a guide sequence and its corresponding target sequence is greater than 94.5%, 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, 99.5%, or 99.9%. In some embodiments, the degree of complementarity is 100%.
It is known in the field that complete complementarity is not required provided that there is sufficient complementarity to be functional. For CRISPR nucleases, modulation of cleavage efficiency can be exploited by introduction of mismatches, e.g., one or more mismatches, such as 1 or 2 mismatches between spacer sequence and target sequence, including the position of the mismatch along the spacer/target. The more central (i.e., not at the 3′ or 5′ ends) a mismatch, e.g., a double mismatch, is located; the more cleavage efficiency is affected. Accordingly, by choosing mismatch positions along the spacer sequence, cleavage efficiency can be modulated. For example, if less than 100% cleavage of targets is desired (e.g., in a cell population), 1 or 2 mismatches between spacer and target sequence can be introduced in the spacer sequences.
The CRISPR-Cas systems described herein have a wide variety of utilities including modifying (e.g., deleting, inserting, translocating, inactivating, or activating) a target polynucleotide in a multiplicity of cell types. The CRISPR-Cas systems have a broad spectrum of applications in, e.g., DNA/RNA detection (e.g., specific high sensitivity enzymatic reporter unlocking (SHERLOCK)), tracking and labeling of nucleic acids, enrichment assays (extracting desired sequence from background), detecting circulating tumor DNA, preparing next generation library, drug screening, disease diagnosis and prognosis, and treating various genetic diseases or disorders, and treating various non-genetic diseases or disorders, or augmenting health via manipulation of the genome.
DNA/RNA Detection
In one aspect, the CRISPR-Cas systems described herein can be used in DNA/RNA detection. Single effector RNA-guided DNases can be reprogrammed with CRISPR RNAs (crRNAs) to provide a platform for specific single-stranded DNA (ssDNA) sensing. Upon recognition of its DNA target, activated Type V single effector DNA-guided DNases engage in “collateral” cleavage of nearby non-targeted ssDNAs. This crRNA-programmed collateral cleavage activity allows the CRISPR-Cas systems to detect the presence of a specific DNA by nonspecific degradation of labeled ssDNA.
The collateral ssDNA activity can be combined with a reporter in DNA detection applications such as a method called the DNA Endonuclease-Targeted CRISPR trans reporter (DETECTR) method, which achieves attomolar sensitivity for DNA detection (see, e.g., Chen et al., Science, 360(6387):436-439, 2018), which is incorporated herein by reference in its entirety. One application of using the enzymes described herein is to degrade non-specific ssDNA in an in vitro environment. A “reporter” ssDNA molecule linking a fluorophore and a quencher can also be added to the in vitro system, along with an unknown sample of DNA (either single-stranded or double-stranded). Upon recognizing the target sequence in the unknown piece of DNA, the effector complex cleaves the reporter ssDNA resulting in a fluorescent readout.
In other embodiments, the SHERLOCK method (Specific High Sensitivity Enzymatic Reporter UnLOCKing) also provides an in vitro nucleic acid detection platform with attomolar (or single-molecule) sensitivity based on nucleic acid amplification and collateral cleavage of a reporter ssDNA, allowing for real-time detection of the target. Methods of using CRISPR in SHERLOCK are described in detail, e.g., in Gootenberg, et al. “Nucleic acid detection with CRISPR-Cas13a/C2c2,” Science, 356(6336):438-442 (2017), which is incorporated herein by reference in its entirety.
In some embodiments, the CRISPR-Cas systems described herein can be used in multiplexed error-robust fluorescence in situ hybridization (MERFISH). These methods are described in, e.g., Chen et al., “Spatially resolved, highly multiplexed RNA profiling in single cells,” Science, 2015 Apr. 24; 348(6233):aaa6090, which is incorporated herein by reference in its entirety.
Tracking and Labeling of Nucleic Acids
Cellular processes depend on a network of molecular interactions among proteins, RNAs, and DNAs. Accurate detection of protein-DNA and protein-RNA interactions is key to understanding such processes. In vitro proximity labeling techniques employ an affinity tag combined with, a reporter group, e.g., a photoactivatable group, to label polypeptides and RNAs in the vicinity of a protein or RNA of interest in vitro. After UV irradiation, the photoactivatable groups react with proteins and other molecules that are in close proximity to the tagged molecules, thereby labelling them. Labelled interacting molecules can subsequently be recovered and identified. The RNA targeting effector proteins can for instance be used to target probes to selected RNA sequences. These applications can also be applied in animal models for in vivo imaging of diseases or difficult-to culture cell types. The methods of tracking and labeling of nucleic acids are described, e.g., in U.S. Pat. No. 8,795,965; WO 2016205764; and WO 2017070605; each of which is incorporated herein by reference in its entirety.
High-Throughput Screening
The CRISPR-Cas systems described herein can be used for preparing next generation sequencing (NGS) libraries. For example, to create a cost-effective NGS library, the CRISPR-Cas systems can be used to disrupt the coding sequence of a target gene, and the CRISPR enzyme transfected clones can be screened simultaneously by next-generation sequencing (e.g., on an Illumina system). A detailed description regarding how to prepare NGS libraries can be found, e.g., in Bell et al., “A high-throughput screening strategy for detecting CRISPR-Cas9 induced mutations using next-generation sequencing,” BMC Genomics, 15.1 (2014): 1002, which is incorporated herein by reference in its entirety.
Engineered Microorganisms
Microorganisms (e.g., E. coli, yeast, and microalgae) are widely used for synthetic biology. The development of synthetic biology has a wide utility, including various clinical applications. For example, the programmable CRISPR-Cas systems can be used to split proteins of toxic domains for targeted cell death, e.g., using cancer-linked RNA as target transcript. Further, pathways involving protein-protein interactions can be influenced in synthetic biological systems with e.g. fusion complexes with the appropriate effectors such as kinases or enzymes.
In some embodiments, RNA guide sequences that target phage sequences can be introduced into the microorganism. Thus, the disclosure also provides methods of vaccinating a microorganism (e.g., a production strain) against phage infection.
In some embodiments, the CRISPR-Cas systems provided herein can be used to engineer microorganisms, e.g., to improve yield or improve fermentation efficiency. For example, the CRISPR-Cas systems described herein can be used to engineer microorganisms, such as yeast, to generate biofuel or biopolymers from fermentable sugars, or to degrade plant-derived lignocellulose derived from agricultural waste as a source of fermentable sugars. More particularly, the methods described herein can be used to modify the expression of endogenous genes required for biofuel production and/or to modify endogenous genes, which may interfere with the biofuel synthesis. These methods of engineering microorganisms are described e.g., in Verwaal et al., “CRISPR/Cpf1 enables fast and simple genome editing of Saccharomyces cerevisiae,” Yeast, 2017 Sep. 8. doi: 10.1002/yea.3278; and Hlavova et al., “Improving microalgae for biotechnology—from genetics to synthetic biology,” Biotechnol. Adv., 2015 Nov. 1; 33:1194-203, both of which are incorporated herein by reference in their entirety.
Application in Plants
The CRISPR-Cas systems described herein have a wide variety of utility in plants. In some embodiments, the CRISPR-Cas systems can be used to engineer genomes of plants (e.g., improving production, making products with desired post-translational modifications, or introducing genes for producing industrial products). In some embodiments, the CRISPR-Cas systems can be used to introduce a desired trait to a plant (e.g., with or without heritable modifications to the genome), or regulate expression of endogenous genes in plant cells or whole plants.
In some embodiments, the CRISPR-Cas systems can be used to identify, edit, and/or silence genes encoding specific proteins, e.g., allergenic proteins (e.g., allergenic proteins in peanuts, soybeans, lentils, peas, green beans, and mung beans). A detailed description regarding how to identify, edit, and/or silence genes encoding proteins is described, e.g., in Nicolaou et al., “Molecular diagnosis of peanut and legume allergy,” Curr. Opin. Allergy Clin. Immunol., 11(3):222-8 (2011), and WO 2016205764 A1; both of which are incorporated herein by reference in their entirety.
Gene Drives
Gene drive is the phenomenon in which the inheritance of a particular gene or set of genes is favorably biased. The CRISPR-Cas systems described herein can be used to build gene drives. For example, the CRISPR-Cas systems can be designed to target and disrupt a particular allele of a gene, causing the cell to copy the second allele to fix the sequence. Because of the copying, the first allele will be converted to the second allele, increasing the chance of the second allele being transmitted to the offspring. A detailed method regarding how to use the CRISPR-Cas systems described herein to build gene drives is described, e.g., in Hammond et al., “A CRISPR-Cas9 gene drive system targeting female reproduction in the malaria mosquito vector Anopheles gambiae,” Nat. Biotechnol., 2016 January; 34(1):78-83, which is incorporated herein by reference in its entirety.
Pooled-Screening
As described herein, pooled CRISPR screening is a powerful tool for identifying genes involved in biological mechanisms such as cell proliferation, drug resistance, and viral infection. Cells are transduced in bulk with a library of RNA guide-encoding vectors described herein, and the distribution of RNA guides is measured before and after applying a selective challenge. Pooled CRISPR screens work well for mechanisms that affect cell survival and proliferation, and they can be extended to measure the activity of individual genes (e.g., by using engineered reporter cell lines). Arrayed CRISPR screens, in which only one gene is targeted at a time, make it possible to use RNA-seq as the readout. In some embodiments, the CRISPR-Cas systems as described herein can be used in single-cell CRISPR screens. A detailed description regarding pooled CRISPR screenings can be found, e.g., in Datlinger et al., “Pooled CRISPR screening with single-cell transcriptome read-out,” Nat. Methods., 2017 March; 14(3):297-301, which is incorporated herein by reference in its entirety.
Saturadon Mutagenesis (“Bashing”)
The CRISPR-Cas systems described herein can be used for in situ saturating mutagenesis. In some embodiments, a pooled RNA guide library can be used to perform in situ saturating mutagenesis for particular genes or regulatory elements. Such methods can reveal critical minimal features and discrete vulnerabilities of these genes or regulatory elements (e.g., enhancers). These methods are described, e.g., in Canver et al., “BCL11A enhancer dissection by Cas9-mediated in situ saturating mutagenesis,” Nature, 2015 Nov. 12; 527(7577):192-7, which is incorporated herein by reference in its entirety.
Quantitative Trait Mapping (crisprQTL)
The CRISPR-Cas systems described herein can be used for mapping coding and non-coding regions of a genome that influence gene expression. For example, in some embodiments, a population of cells may be transduced with multiple random, barcoded, CRISPR guide RNA-programmed perturbations in each cell. Single-cell RNA-sequencing may then be used to profile gene expression and the collection of RNA guides in each cell. The generated data can then be used to identify associations between RNA guides and quantitative changes in gene expression, which facilitates the analysis of the cis-regulatory architecture of the cells. These methods are described, for example, in Gasperini et al., “crisprQTL mapping as a genome-wide association framework for cellular genetic screens,” bioRxiv 314344, posted May 4, 2018, doi: doi.org/10.1101/314344, which is incorporated herein by reference in its entirety.
Therapeutic Applications
The CRISPR-Cas systems described herein can have various therapeutic applications. In some embodiments, the new CRISPR-Cas systems can be used to treat various diseases and disorders, e.g., genetic disorders (e.g., monogenetic diseases), diseases that can be treated by nuclease activity (e.g., Pcsk9 targeting, Duchenne Muscular Dystrophy (DMD), BCL11a targeting), and various cancers, etc.
In some embodiments, the CRISPR-Cas systems described herein can be used to edit a target nucleic acid to modify the target nucleic acid (e.g., by inserting, deleting, or mutating one or more amino acid residues). For example, in some embodiments the CRISPR-Cas systems described herein comprise an exogenous donor template nucleic acid (e.g., a DNA molecule or an RNA molecule), which comprises a desirable nucleic acid sequence. Upon resolution of a cleavage event induced with the CRISPR-Cas system described herein, the molecular machinery of the cell utilizes the exogenous donor template nucleic acid in repairing and/or resolving the cleavage event. Alternatively, the molecular machinery of the cell can utilize an endogenous template in repairing and/or resolving the cleavage event. In some embodiments, the CRISPR-Cas systems described herein may be used to alter a target nucleic acid resulting in an insertion, a deletion, and/or a point mutation). In some embodiments, the insertion is a scarless insertion (i.e., the insertion of an intended nucleic acid sequence into a target nucleic acid resulting in no additional unintended nucleic acid sequence upon resolution of the cleavage event). Donor template nucleic acids may be double stranded or single stranded nucleic acid molecules (e.g., DNA or RNA). Methods of designing exogenous donor template nucleic acids are described, for example, in PCT Publication No. WO 2016094874 A1, the entire contents of which are expressly incorporated herein by reference.
In one aspect, the CRISPR-Cas systems described herein can be used for treating a disease caused by overexpression of RNAs, toxic RNAs, and/or mutated RNAs (e.g., splicing defects or truncations). For example, expression of the toxic RNAs may be associated with the formation of nuclear inclusions and late-onset degenerative changes in brain, heart, or skeletal muscle. In some embodiments, the disorder is myotonic dystrophy. In myotonic dystrophy, the main pathogenic effect of the toxic RNAs is to sequester binding proteins and compromise the regulation of alternative splicing (see, e.g., Osborne et al., “RNA-dominant diseases,” Hum. Mol. Genet., 2009 Apr. 15; 18(8):1471-81). Myotonic dystrophy (dystrophia myotonica (DM)) is of particular interest to geneticists because it produces an extremely wide range of clinical features. The classical form of DM, which is now called DM type 1 (DM1), is caused by an expansion of CTG repeats in the 3′-untranslated region (UTR) of DMPK, a gene encoding a cytosolic protein kinase. The CRISPR-Cas systems as described herein can target overexpressed RNA or toxic RNA, e.g., the DMPK gene or any of the mis-regulated alternative splicing in DM1 skeletal muscle, heart, or brain.
The CRISPR-Cas systems described herein can also target trans-acting mutations affecting RNA-dependent functions that cause various diseases such as, e.g., Prader Willi syndrome, Spinal muscular atrophy (SMA), and Dyskeratosis congenita. A list of diseases that can be treated using the CRISPR-Cas systems described herein is summarized in Cooper et al., “RNA and disease,” Cell, 136.4 (2009): 777-793, and WO 2016205764 A1, both of which are incorporated herein by reference in their entirety. Those of skill in this field will understand how to use the new CRISPR-Cas systems to treat these diseases.
The CRISPR-Cas systems described herein can also be used in the treatment of various tauopathies, including, e.g., primary and secondary tauopathies, such as primary age-related tauopathy (PART)/Neurofibrillary tangle (NFT)-predominant senile dementia (with NFTs similar to those seen in Alzheimer Disease (AD), but without plaques), dementia pugilistica (chronic traumatic encephalopathy), and progressive supranuclear palsy. A useful list of tauopathies and methods of treating these diseases are described, e.g., in WO 2016205764, which is incorporated herein by reference in its entirety.
The CRISPR-Cas systems described herein can also be used to target mutations disrupting the cis-acting splicing codes that can cause splicing defects and diseases. These diseases include, e.g., motor neuron degenerative disease that results from deletion of the SMN1 gene (e.g., spinal muscular atrophy), Duchenne Muscular Dystrophy (DMD), frontotemporal dementia, and Parkinsonism linked to chromosome 17 (FTDP-17), and cystic fibrosis.
The CRISPR-Cas systems described herein can further be used for antiviral activity, in particular against RNA viruses. The effector proteins can target the viral RNAs using suitable RNA guides selected to target viral RNA sequences.
Furthermore, in vitro RNA sensing assays can be used to detect specific RNA substrates. The RNA targeting effector proteins can be used for RNA-based sensing in living cells. Examples of applications are diagnostics by sensing of, for examples, disease-specific RNAs.
A detailed description of therapeutic applications of the CRISPR-Cas systems described herein can be found, e.g., in U.S. Pat. No. 8,795,965, EP 3009511, WO 2016205764, and WO 2017070605; each of which is incorporated herein by reference in its entirety.
Delivery of CRISPR-Cas Systems
Through this disclosure and the knowledge in the art, the CRISPR-Cas systems described herein, or components thereof, nucleic acid molecules thereof, or nucleic acid molecules encoding or providing components thereof, can be delivered by various delivery systems such as vectors, e.g., plasmids, viral delivery vectors. The new CRISPR enzymes and/or any of the RNAs (e.g., RNA guides) can be delivered using suitable vectors, e.g., plasmids or viral vectors, such as adeno-associated viruses (AAV), lentiviruses, adenoviruses, and other viral vectors, or combinations thereof. The proteins and one or more RNA guides can be packaged into one or more vectors, e.g., plasmids or viral vectors.
In some embodiments, the vectors, e.g., plasmids or viral vectors, are delivered to the tissue of interest by, e.g., intramuscular injection, intravenous administration, transdermal administration, intranasal administration, oral administration, or mucosal administration. Such delivery may be either via a single dose or multiple doses. One skilled in the art understands that the actual dosage to be delivered herein may vary greatly depending upon a variety of factors, such as the vector choices, the target cells, organisms, tissues, the general conditions of the subject to be treated, the degrees of transformation/modification sought, the administration routes, the administration modes, the types of transformation/modification sought, etc.
In certain embodiments, the delivery is via adenoviruses, which can be at a single dose containing at least 1×105 particles (also referred to as particle units, pu) of adenoviruses. In some embodiments, the dose preferably is at least about 1×106 particles, at least about 1×107 particles, at least about 1×108 particles, and at least about 1×109 particles of the adenoviruses. The delivery methods and the doses are described, e.g., in WO 2016205764 A1 and U.S. Pat. No. 8,454,972 B2, both of which are incorporated herein by reference in their entirety.
In some embodiments, the delivery is via a recombinant adeno-associated virus (rAAV) vector. For example, in some embodiments, a modified AAV vector may be used for delivery. Modified AAV vectors can be based on one or more of several capsid types, including AAV1, AV2, AAV5, AAV6, AAV8, AAV 8.2, AAV9, AAV rhlO, modified AAV vectors (e.g., modified AAV2, modified AAV3, modified AAV6) and pseudotyped AAV (e.g., AAV2/8, AAV2/5 and AAV2/6). Exemplary AAV vectors and techniques that may be used to produce rAAV particles are known in the art (see, e.g., Aponte-Ubillus et al. (2018) Appl. Microbiol. Biotechnol. 102(3): 1045-54; Zhong et al. (2012) J. Genet. Syndr. Gene Ther. S1: 008; West et al. (1987) Virology 160: 38-47 (1987); Tratschin et al. (1985) Mol. Cell. Biol. 5: 3251-60); U.S. Pat. Nos. 4,797,368 and 5,173,414; and International Publication Nos. WO 2015/054653 and WO 93/24641, each of which is incorporated herein by reference in its entirety).
In some embodiments, the delivery is via plasmids. The dosage can be a sufficient number of plasmids to elicit a response. In some cases, suitable quantities of plasmid DNA in plasmid compositions can be from about 0.1 to about 2 mg. Plasmids generally include (i) a promoter, (ii) a sequence encoding a nucleic acid-targeting CRISPR enzymes, operably linked to the promoter; (iii) a selectable marker, (iv) an origin of replication; and (v) a transcription terminator downstream of and operably linked to (ii). The plasmids can also encode the RNA components of a CRISPR complex, but one or more of these may instead be encoded on different vectors. The frequency of administration is within the ambit of the medical or veterinary practitioner (e.g., physician, veterinarian), or a person skilled in the art.
In another embodiment, the delivery is via liposomes or lipofectin formulations and the like, and can be prepared by methods known to those skilled in the art. Such methods are described, for example, in WO 2016205764 and U.S. Pat. Nos. 5,593,972; 5,589,466; and 5,580,859; each of which is incorporated herein by reference in its entirety.
In some embodiments, the delivery is via nanoparticles or exosomes. For example, exosomes have been shown to be particularly useful in delivery RNA.
Further means of introducing one or more components of the new CRISPR-Cas systems to the cell is by using cell penetrating peptides (CPP). In some embodiments, a cell penetrating peptide is linked to the CRISPR enzymes. In some embodiments, the CRISPR enzymes and/or RNA guides are coupled to one or more CPPs to transport them inside cells effectively (e.g., plant protoplasts). In some embodiments, the CRISPR enzymes and/or RNA guide(s) are encoded by one or more circular or non-circular DNA molecules that are coupled to one or more CPPs for cell delivery.
CPPs are short peptides of fewer than 35 amino acids derived either from proteins or from chimeric sequences capable of transporting biomolecules across cell membrane in a receptor independent manner. CPPs can be cationic peptides, peptides having hydrophobic sequences, amphipathic peptides, peptides having proline-rich and anti-microbial sequences, and chimeric or bipartite peptides. Examples of CPPs include, e.g., Tat (which is a nuclear transcriptional activator protein required for viral replication by HIV type 1), penetratin, Kaposi fibroblast growth factor (FGF) signal peptide sequence, integrin β3 signal peptide sequence, polyarginine peptide Args sequence, Guanine rich-molecular transporters, and sweet arrow peptide. CPPs and methods of using them are described, e.g., in Hallbrink et al., “Prediction of cell-penetrating peptides,” Methods Mol. Biol., 2015; 1324:39-58; Ramakrishna et al., “Gene disruption by cell-penetrating peptide-mediated delivery of Cas9 protein and guide RNA,” Genome Res., 2014 June; 24(6):1020-7; and WO 2016205764 A1; each of which is incorporated herein by reference in its entirety.
Various delivery methods for the CRISPR-Cas systems described herein are also described, e.g., in U.S. Pat. No. 8,795,965, EP 3009511, WO 2016205764, and WO 2017070605; each of which is incorporated herein by reference in its entirety.
The invention is further described in the following examples, which do not limit the scope of the invention described in the claims.
Genome and metagenome sequences were downloaded from NCBI (Benson et al., 2013; Pruitt et al., 2012), NCBI whole genome sequencing (WGS), and DOE JGI Integrated Microbial Genomes (Markowitz et al., 2012) and processed as described in the Detailed Description of this disclosure.
The identified CRISPR-Cas system described herein, designated CLUST.018837, contains a large single effector associated with CRISPR arrays found in Acidithiobacillus, Clostridiales, Gordonia, Metallibacterium, Mycobacterium, Pelobacter, Rhodanobacter, Thioalkalivibrio, and Thiobacillus bacteria, as well as uncultured metagenomic sequences collected from a range of environments, including termite gut, soil, ground water, waste water, marine, and hot springs environments (TABLE 1). CLUST.018837 effectors include the exemplary proteins detailed in TABLES 1 and 2. Exemplary direct repeat sequences for these systems are shown in TABLE 3.
Having identified the minimal components of CLUST.018837 CRISPR-Cas systems, multiple example systems were selected for functional validation, from the sources designated NZ_LDOS01000005 (SEQ ID NO: 1), 3300009004 (SEQ ID NO: 9), APMI01033782 (SEQ ID NO: 26), NZ_LVXZ01000012 (SEQ ID NO: 3), and ADIG01000806 (SEQ ID NO: 20).
To test the activity of an exemplary CLUST.018837 CRISPR-Cas system, systems containing the pET28a(+) vector were designed and synthesized. The E. coli codon-optimized nucleic acid sequences encoding the selected CLUST.018837 effector proteins (amino acid sequence provided in TABLE 2) were synthesized (Genscript) and cloned into a custom expression system derived from the pET-28a(+) (EMD-Millipore) to create the Effector Plasmid. The engineered, non-naturally occurring vector included a nucleic acid encoding the CLUST.018837 effector protein under the control of a lac promoter and an E. coli ribosome binding sequence. The vector also included an acceptor site for a CRISPR array library driven by a J23119 promoter following the open reading frame for the CLUST.018837 effector protein (
For the minimal CRISPR array, oligonucleotide library synthesis (OLS) pools comprising two direct repeats flanking natural-length spacer sequences targeting the pACYC184 plasmid, select E. coli essential genes, and non-targeting negative control spacers were designed for a total of 8900 elements in the array library. The spacer length was determined by the mode of the spacer lengths found in the endogenous CRISPR array. Flanking the minimal CRISPR array were unique PCR priming sites that enabled amplification of a specific library from a larger pool of oligo synthesis. These sequences were placed under the control of a J23119 promoter and cloned into the Effector Plasmid in both the forward and reverse orientations for a total library of ˜18,000 plasmid elements
The minimal CRISPR array library was next cloned into the Effector Plasmid using the Golden Gate assembly method. Briefly, each minimal CRISPR array from the OLS pool (Agilent Genomics) was first amplified using unique PCR primers, and pre-linearized the plasmid backbone using BsaI to reduce potential background. Both DNA fragments were purified with Ampure® XP (Beckman Coulter) prior to addition to Golden Gate Assembly Master Mix (New England Biolabs) and incubated per the manufacturer's instructions. The Golden Gate reaction was further purified and concentrated to enable maximum transformation efficiency in the subsequent steps of the bacterial screen.
The plasmid library containing the distinct minimal CRISPR array and CLUST.018837 effector sequence was electroporated into E. Cloni® electrocompetent E. coli (Lucigen) using a Gene Pulser Xcell® (BioRad) following the protocol recommended by Lucigen. The library was co-transformed with purified pACYC184 plasmid, plated onto agar containing chloramphenicol (Fisher), tetracycline (Alfa Aesar), and kanamycin (Alfa Aesar) in BioAssay® dishes (Thermo Fisher), and incubated for 10-12 hours at 37° C. After estimation of approximate colony count to ensure sufficient library representation on the bacterial plate, the bacteria were harvested and plasmid DNA extracted using a QIAprep Spin Miniprep® Kit (Qiagen) to create an “output library.” By performing a PCR using custom primers containing barcodes and sites compatible with Illumina sequencing chemistry, a barcoded next generation sequencing library was generated from both the pre-transformation “input library” and the post-harvest “output library,” which were then pooled and loaded onto a Nextseq 550 (Illumina) to evaluate the effectors. At least two independent biological replicates were performed for each screen to ensure consistency.
Next generation sequencing (NGS) data for screen input and output libraries were demultiplexed using Illumina bcl2fastq. Reads in resulting fastq files for each sample contained the CRISPR array elements for the screening plasmid library. The direct repeat sequence of the CRISPR array was used to determine the array orientation, and the spacer sequence was mapped to the source (pACYC184 or E. coli essential genes) or negative control sequence (GFP) to determine the corresponding target.
To identify specific parameters resulting in enzymatic activity and bacterial cell death, NGS was used to quantify and compare the representation of individual CRISPR arrays (i.e., repeat-spacer-repeat) in the PCR product of the input and output plasmid libraries. The array depletion ratio was defined as the normalized output read count divided by the normalized input read count. An array was considered to be “strongly depleted” if the depletion ratio was less than 0.33 (more than 3-fold depletion). When calculating the array depletion ratio across biological replicates, the maximum depletion ratio value for a given CRISPR array across all experiments (i.e., a strongly depleted array must be strongly depleted in all biological replicates) was taken. A matrix including array depletion ratios and the following features for each spacer target: target strand, transcript targeting, ORI targeting, target sequence motifs, flanking sequence motifs, and target secondary structure were generated. The degree to which different features in this matrix explained target depletion for CLUST.018837 systems was investigated, thereby yielding a broad survey of functional parameters within a single screen.
A matrix including array depletion ratios and the following features for each spacer target: target strand, transcript targeting, ORI targeting, target sequence motifs, flanking sequence motifs, and target secondary structure were generated. The degree to which different features in this matrix explained target depletion for CLUST.018837 systems was investigated, thereby yielding a broad survey of functional parameters within a single screen.
To quantify depletion activity, an enrichment ratio was calculated as Rtreated/Rinput for each direct repeat and spacer. The normalized input read count was computed as:
R
input=# reads containing DR+spacer/total reads
where the reads counts were obtained from next-generation sequencing of the plasmid DNA library expressing a CLUST.018837 effector and associated crRNA prior to transformation. The normalized treated read count was computed as:
R
treated=(1+# reads containing DR+spacer)/total reads
where the read counts were obtained from next-generation sequencing of the plasmid DNA extracted from the surviving cells expressing CLUST.018837 effector and associated crRNA after antibiotic screening. A strongly depleted target had an enrichment less than ⅓, which was marked by the first vertical dashed line. Each CLUST.018837 effector was paired with a CRISPR array that took the form 5′-DR-[spacer]-DR-3′ or 5′-reverse_complement(DR)-[spacer]-reverse_complement(DR)-3′, and the depletion activity of both orientations of the DR are shown in the figure as indicated in the legend.
The results are plotted for each DR transcriptional orientation. In the functional screen for each composition, an active effector complexed with an active crRNA (expressed as a DR::spacer::DR) interferes with the ability of the pACYC184 to confer E coli resistance to chloramphenicol and tetracycline, resulting in cell death and depletion of the spacer element within the pool. Comparing the results of deep sequencing the initial DNA library (screen input) versus the surviving transformed E. coli (screen output) suggest specific target sequences and DR transcriptional orientation that enable an active, programmable CRISPR-Cas system. The screen also indicates that the effector complex is only active with one orientation of the DR.
RNA-Sequencing Mature crRNA from In Vivo Bacterial Screen
Sequencing the small RNA from the in vivo bacterial screen began by extracting total RNA from harvested screen bacteria using the Direct-zol RNA MiniPrep® Plus w/ TRI Reagent (Zymo Research). Ribosomal RNA was removed using a Ribo-Zero® rRNA Removal Kit for Bacteria, followed by cleanup using an RNA Clean and Concentrator-5 kit. The resultant ribosomal RNA depleted total RNA was treated with T4 PNK, RNA 5′ polyphosphatase, prepared for sequencing using the NEBNext® Small RNA Library Prep Set.
The pre-crRNA processing in the screen output samples for the direct repeat orientation that demonstrated successful targeting of pACYC184 and E. coli essential genes was investigated.
In an effort to reconstitute processing of the NZ_LDOS0100005 pre-crRNA into a mature crRNA in vitro, a pre-crRNA oligonucleotide template containing a T7 promoter followed the sequence, direct repeat (DR)-spacer1-DR-spacer2-DR, was synthesized. The purified oligonucleotide template was PCR amplified to select for full-length products and expressed the pre-crRNA using T7 in vitro transcription. The in vitro transcribed pre-crRNA was incubated with 0.0675 uM-1 μM of purified NZ_LDOS0100005 in 1×NEB Buffer2 with or without magnesium for 30 min. at 37° C. The resulting product was treated with proteinase K, supplemented with EDTA, denatured at 65° C. for 3 min., and run out on a 15% TBE-urea PAGE gel for analysis by SYBR-gold staining.
DNA-modifying CRISPR-Cas systems such as CLUST.018837, systems described herein have important applications in eukaryotic cells such as therapeutic modification of the genome, with example modifications including but not limited to; genotype correction, gene knockout, genetic sequence insertion/deletion (by homology directed repair or otherwise), single nucleotide modification, or gene regulation. These gene modification modalities can utilize either natural or engineered activities of the CLUST.018837 CRISPR-Cas systems.
Without wishing to be limited, the applications in eukaryotic cells for the CLUST.018837 CRISPR-Cas system can be divided up into those utilizing nuclease and non-nuclease (also known as nuclease-dead) functionalities. For nucleases, in some embodiments, the natural nuclease activity of the CLUST.018837 CRISPR effector may be sufficient for applications such as gene modification, while in other embodiments, the targeted nuclease activity can be augmented by the fusion of additional nuclease domains (such as FokI) to either a nuclease-weak or nuclease-inactivated CLUST.018837 CRISPR effector. For non-nuclease functionalities, such nuclease-weak or nuclease inactivated CLUST.018837 CRISPR effectors can either be used directly or be fused to other functional domains. Both nuclease and non-nuclease functionalities are subsequently described in greater detail.
To develop CLUST.018837 CRISPR Cas systems for eukaryotic applications, the constructs encoding the protein effectors and/or their fusions are first codon-optimized for expression in mammalian cells, and specific localization tags are optionally appended to either or both the N-terminus or C-terminus of the effector protein. These localization tags can include sequences such as nuclear localization signal (NLS) sequences, which localize the effector to the nucleus for modification of genomic DNA. Other accessory proteins, such as fluorescent proteins, may be further appended. It has been demonstrated that the addition of robust, “superfolding” proteins such as superfolding green fluorescent protein (GFP) can increase the activity of CRISPR enzymes in mammalian cells when appended to the effector (Abudayyeh et al. (2017) Nature 550(7675): 280-4, and Cox et al. (2017) Science 358(6366): 1019-27).
The codon-optimized sequence coding for the CLUST.018837 effector and appended accessory proteins, fusion proteins, and/or localization signals is then cloned into a eukaryotic expression vector with the appropriate 5′ Kozak eukaryotic translation initiation sequence, eukaryotic promoters, and polyadenylation signals. In mammalian expression vectors, these promoters can include, e.g., general promoters such as CMV, EF1a, EFS, CAG, SV40, and cell-type specific RNA polymerase II promoters such as Syn and CamKIIa for neuronal expression, and thyroxine binding globulin (TBG) for hepatocyte expression to name a few. Similarly, useful polyadenylation signals include, but are not limited to, SV40, hGH, and BGH. For expression of the pre-crRNA or mature crRNA, RNA polymerase III promoters such as H1 or U6 can be used.
Delivery of the complete effector and RNA guide to the eukaryotic cells or tissues of choice can come in many different forms. For delivery to cells, in some embodiments. Transfection or nucleofection can deliver DNA or RNA from which the protein and/or RNA guide(s) is/are synthesized and assembled by the cellular machinery into active protein complexes, or the ribonucleoproteins (RNPs) themselves can be pre-formed extracellularly and delivered as a complete complex. Other applications may require the use of viral delivery, in which case the eukaryotic expression vector can be a lentiviral plasmid backbone, adeno-associated viral (AAV) plasmid backbone, or similar plasmid backbone capable of use in recombinant viral vector production. In particular, the small size of the CLUST.018837 CRISPR effectors make them ideally make them ideally suited for packaging, even when fused with other functional domains, along with its crRNA and appropriate control sequences into a single adeno-associated virus particle; the packaging size limit of 4.7 kb for AAV may preclude the use of larger effectors, particularly if large cell-type specific promoters are used for expression control.
After adapting the sequences, delivery vectors, and methods for eukaryotic and mammalian use, the different constructs as described herein are characterized for performance. For nuclease-based applications, in some instances, for testing of the mammalian nuclease activity of various constructs, a genomic dsDNA cleavage assay was used with either NGS or Surveyor nuclease readout to quantify the efficiency of indel formation (Hsu et al. (2013). In addition to testing various construct configurations and accessory sequences on individual targets, pooled library-based approaches are used to determine 1) any targeting dependency of specific constructs in mammalian cells as well as 2) the effect of mismatch locations and combinations along the length of the targeting crRNA. Briefly, the pooled library includes a selection plasmid that expresses a target DNA containing different flanking sequences as well as mismatches to the guide or guides used in the screening experiment, such that the successful target recognition and cleavage results in depletion of the sequence from the library. Furthermore, targeted indel sequencing or unbiased genome-wide cleavage assays can be used to evaluate the specificity of the CLUST.018837 nuclease constructs (Hsu et al. (2013), Tsai et al. (2015), Kim et al. (2015), Tsai et al. (2017)).
In addition to nuclease-based genome editing using CLUST.018837 effectors and a crRNA, additional template DNA sequences can be co-delivered either in a vector, such as an AAV viral vector, or as linear single stranded or double stranded DNA fragments. For insertion of template DNA by homology directed repair (HDR), template sequences are designed containing a payload sequence to be inserted into the locus of interest as well as flanking sequences that are homologous to endogenous sequences flanking the desired insertion site. In some instances, for insertion of short DNA payloads less than (for example: less than 1 kb in length), flanking homologous sequences can be short (for example: ranging from 15 to 200 nt in length). In other instances, for the insertion of long DNA payloads (for example: 1 kb or greater in length), long homologous flanking sequences are required to facilitate efficient HDR (for example: greater than 200 nt in length). Cleavage of target genomic loci for HDR between sequences homologous to template DNA flanking regions can significantly increase the frequency of HDR. CLUST.018837 effector cleavage events facilitating HDR include, but are not limited to dsDNA cleavage, double nicking, and single strand nicking activity.
Applications can also be based on non-nuclease functionalities of the CLUST.018837 effector and constructs from the fusion of the effector with a functional domain. In this context, the CLUST.018837 effector refers to both the natural effector amino acid sequence as well as any functional modifications to reduce or eliminate its nuclease activity. CLUST.018837 effectors have programmable DNA binding activity, which can be directly used in applications such as DNA immunoprecipitation, or other domains can be appended onto the effector to provide further functionality. Activities of these domains include, but are not limited to, DNA base modification (ex: ecTAD and its evolved forms, APOBEC), DNA methylation (m6A methyltransferases and demethylases), localization factors (KDEL retention sequence, mitochondrial targeting signal), transcription modification factors (ex: KRAB, VP64). Additionally, domains can be appended to provide additional control, such as light-gated control (cryptochromes) and chemically inducible components (FKBP-FRB chemically inducible dimerization).
Optimizing the activity of such fusion proteins requires a systematic way of comparing linkers that connect the CLUST.018837 effector with the appended domain. These linkers may include, but are not limited to, flexible glycine-serine (GS) linkers in various combinations and lengths, rigid linkers such as the alpha-helix forming EAAAK sequence, XTEN linker (Schellenberger V, et al. Nat. Biotechnol. 2009; 27:1186-1190), as well as different combinations thereof (see TABLE 5). The various designs are then assayed in parallel over the same crRNA target complex and functional readout to determine which one yields the desired properties.
For adapting CLUST.018837 effectors for use in targeted DNA base modification (see, e.g., Gaudelli et al. (2017) “Programmable base editing of A•T to G•C in genomic DNA without DNA cleavage” Science 25 Oct. 2017), one begins with a panel of CLUST.018837 effectors that yielded strong interference activity in in vivo E. coli bacterial screens. These effectors, whether with nuclease-inactivating mutations or in their natural forms, are mammalian codon optimized and tested for specific and programmable dsDNA binding in an in vitro environment such as using an electrophoretic mobility shift assay (EMSA).
Next, a linker is used to create the fusion protein between CLUST.018837 effector and the base editing domain. Initially, this domain consists of the ecTadA(wt)/ecTadA*(7.10) heterodimer (hereafter referred to as the dCas12i-TadA heterodimer) engineered previously for hyperactivity and modification of dsDNA A•T dinucleotides to G•C (TABLE 7). Given the structural differences between the smaller CLUST.018837 effectors versus the previously characterized Cas9 effectors, alternate linker designs and lengths may yield the optimal design of the base editing fusion protein. Further optimization of the location of the nuclear localization sequence may also be required.
To evaluate the activity of the CLUST.018837-derived base editors, the HEK 293T cells are transiently transfected with the CLUST.018837 effector-TadA heterodimer construct, a plasmid expressing the crRNA, and optionally, a reporter plasmid if targeting the reporter and not an endogenous locus. The cells are harvested 48 hours after transient transfection, and the DNA is extracted and prepared for next generation sequencing. Analysis of the base composition of loci of samples containing the targeting vs. negative control non-targeting crRNAs provide information about the editing efficiency, and analysis of the sequences at computationally predicted sites of close sequence similarity yields information about the off-target activity.
One particular advantage of developing a DNA base editing system using CLUST.018837 effectors is that the small size, smaller than the existing Cas9 and Cas12a effectors, enables more ready packaging in AAV of CLUST.018837 effector-TadA heterodimer along with its crRNA and control elements without the need for protein truncations. This all-in-one AAV vector enables greater efficacy of in vivo base editing in tissues, which is particularly relevant as a path towards therapeutic applications of CLUST.018837 effectors.
To recapitulate interference activity seen in in vivo screens, effectors were targeted against GFP in an in vitro transcription-translation assay. Pre-crRNAs under a 17 promoter containing direct repeat (DR)-spacer-direct repeat (DR), with a spacer targeting GFP, were PCR amplified to select for full-length product. Effector and sigma28 templates also under a T7 promoter, and RFP and GFP templates under a fliC promoter were PCR amplified as well. All templates were then incubated together in an in vitro transcription-translation assay at 37° C. GFP and RFP fluorescence were read every 10 minutes by a TECAN Infinite M Plex plate reader for 12 hours.
To calculate the fold depletion of GFP fluorescence, GFP signal was normalized to RFP signal at each time point, then the average fluorescence of two technical replicates was taken. GFP fluorescence depletion was then calculated by dividing the GFP signal of an effector incubated with a non-GFP targeting pre-crRNA by the GFP signal of an effector incubated with a GFP targeting pre-crRNA. Depletion of the GFP signal indicates that the effector has formed a functional RNP and interfered with the production of GFP.
Pre-crRNA 17 template DNA sequences and primers used in the in vitro transcription-translation assay are listed in Table 6. Sequences for the GFP linear DNA and plasmid target DNA used for the in vitro transcription-translation assay are set forth in SEQ ID NO: 1075 and SEQ ID NO: 1076, respectively.
To assess the roles of the conserved putative RuvC domains found in NZ_LDOS01000005 and ADIG01000806 systems, point mutants were generated within putative RuvC I (H297A, D303A for NZ_LDOS01000005, H300A, D306A for ADIG01000806), RuvC II (E311A, D504A for NZ_LDOS01000005 and E332A. E516A for ADIG01000806), and RuvC III (D559A for NZ_LDOS01000005 and D569A for ADIG01000806) motifs and the resultant variants were evaluated for in vitro interference activity.
Detection of Supercoiled dsDNA Cleavage by Type V-UI CRISPR Effectors
To elucidate the molecular basis of interference of gene expression by the NZ_LDOS01000005 and ADIG01000806 systems, reactions from the above in vitro GFP interference assay were prepared for next generation sequencing (NGS). Reactions were quenched with EDTA and RNAse, then SPRI purified to isolate plasmid DNA. The plasmid DNA was then treated with NEBNext dsDNA Fragmentase (NEB) to generate fragments of DNA of ˜75 or 150 base pairs (bio-replicate 1 and 2, respectively) in length.
Fragments were then prepared for Illumiina next generation sequencing using New England Biolab's NEBNext Ultra DNA Library Prep Kit for Illumina. Sequencing was performed on an Illumina NextSeq 550 using. Reads were aligned to the sequence of GFP plasmid and normalized to total reads. Both NZ_LDOS01000005 and ADIG01000806 displayed nuclease activity when either the top or bottom strand was targeted across two biological replicates, with NZ_LDOS01000005 having a higher average cleavage frequency than ADIG01000806.
It is to be understood that while the invention has been described in conjunction with the detailed description thereof, the foregoing description is intended to illustrate and not limit the scope of the invention, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are within the scope of the following claims.
This application claims priority to U.S. Ser. No. 62/812,919, filed Mar. 1, 2019, and U.S. Ser. No. 62/869,454, filed Jul. 1, 2019. The content of each of the foregoing applications is hereby incorporated by reference in its entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2020/020426 | 2/28/2020 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62812919 | Mar 2019 | US | |
| 62869454 | Jul 2019 | US |
