Patent Application
20210340510
The present invention relates to the field of genetic engineering, particularly to a fumonisin degrading enzyme FumDPS, gene and application thereof.
Fumonisins (FB) are a water-soluble secondary metabolites produced by Fusarium spp. under specific conditions and are diesters composed of polyhydric alcohols and propionic tricarboxylic acids, with the main active functional groups of primary amines, tricarboxylic acids, hydroxyl groups and aliphatic skeletons, which are closely related to their toxic effects. It has been reported that fumonisin can cause renal tumor and liver cancer in rats, leukomalacia equina (ELEM), pulmonary edema (PPE) in pigs, and is closely related to the pathogenesis of human esophageal cancer. Up to now, 28 analogues of fumonisin have been found, which can be divided into four categories of FA, FB, FC and FP, wherein FB series mainly include fumonisins B1 (FB1), B2 (FB2) and B3 (FB3) in nature, wherein FB1 accounts for about 70% to 80% of the total amount in nature, is the most toxic and the most extensively polluted. Fumonisins can be removed by physical and chemical methods, wherein chemical methods have great limitations of introducing new chemicals and increasing the potential safety risks, in spite of reducing the content of FB1, which is prohibited to eliminate mycotoxins in the European Union, and physical method can remove a certain amount of fumonisin, but its requirements are hard to match and easily change the quality and flavor of food. The biodegradation of fumonisin has the advantages of mild reaction, strong specificity and wide application prospect.
The pollution of mycotoxins is increasing all over the world, which causes the waste of valuable food resources and is carcinogenic to human beings. Therefore, the research of enzymes for degrading mycotoxin can well prevent the contaminated food crops from producing the toxin and retrieve economic losses.
In order to degrade fumonisin by biodegradation method, the present invention provides fumonisin degrading enzyme FumDPS, gene and application thereof.
The order of the present invention is to provide a fumonisin degrading enzyme FumDPS.
Another order of the present invention is to provide a gene encoding said fumonisin degrading enzyme FumDPS.
Another order of the present invention is to provide a recombinant expression vector comprising said gene encoding fumonisin degrading enzyme FumDPS.
Another order of the present invention is to provide a recombinant strain comprising said gene encoding fumonisin degrading enzyme FumDPS.
Another order of the present invention is to provide a method for preparing the above fumonisin degrading enzyme FumDPS.
Another order of the present invention is to provide application of said fumonisin degrading enzyme FumDPS.
In a preferred embodiment of the present invention, said fumonisin degrading enzyme FumDPS comprises the amino acid sequence of SEQ ID No: 1 having 552 amino acids and one stop codon, and a signal peptide of 54 amino acids in N-terminal.
Therefore, the theoretical molecular weight of mature FumDPS is 53.26 kDa and the mature FumDPS has the amino acid sequence of SEQ ID NO:2.
In a yet preferred embodiment of the present invention, the amino acid sequence of FumDPS has 90% to 99% consistency with the sequence of SEQ ID NO: 1, preferably 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% consistency.
In a yet preferred embodiment of the present invention, the amino acid sequence of FumDPS has 90% to 99% consistency with the sequence of SEQ ID NO: 2, preferably 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% consistency.
The present invention provides a gene encoding said fumonisin degrading enzyme FumDP, comprises a nucleotide sequence of SEQ ID NO:3.
The present invention provides a gene encoding a mature fumonisin degrading enzyme FumDP, and comprises the nucleotide sequence of SEQ ID NO:4.
In a yet preferred embodiment of the present invention, the nucleotide sequence of said gene encoding said fumonisin degrading enzyme FumDPS has 90% to 99% consistency with the sequence of SEQ ID NO: 3, preferably 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% consistency.
In a yet preferred embodiment of the present invention, the nucleotide sequence of said gene encoding said fumonisin degrading enzyme FumDPS has 90% to 99% consistency with the sequence of SEQ ID NO: 4, preferably 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% consistency.
In a yet preferred embodiment of the present invention, the gene encoding said fumonisin degrading enzyme FumDPS is isolated and cloned by PCR method, and has the full length of 1659 bp as shown by DNA sequence analysis.
The fumonisin degrading enzyme FumDPS of the present invention has 45% identity of amino acid sequence with that of sphingosine box bacteria MTA 144, and is a new fumonisin degrading enzyme by BLASTting in GenBank.
The present invention provides a recombinant vector comprising the gene encoding said fumonisin degrading enzyme FumDPS, named pET28a (+)—FumDPS. The gene encoding said fumtoxin degrading enzyme of the present invention is inserted between the suitable restriction enzyme sites of the expression vector, so as to be operably connected with the expression regulation sequence. In the preferred embodiment of the present invention, it is preferred to insert the fumonisin degrading enzyme gene between the restriction site of EcoR I and Xho I of the plasmid pET28a (+), so that the nucleotide sequence is located downstream of T7 promoter and regulated by it, so as to obtain the recombinant Escherichia coli expression plasmid pET28a (+)-FumDPS.
The present invention also provides a recombinant strain containing said gene encoding said fumonisin degrading enzyme FumDPS, and said strain is preferably Escherichia coli.
The preparation method of fumonisin degrading enzyme FumDPS according to the present invention comprises the following steps of transforming the host cells with the recombinant vector containing the gene encoding the fumonisin degrading enzyme FumDPS to obtain the recombinant strain; cultivating the obtained recombinant strain to induce the expression of fumonisin degrading enzyme; and isolating and purifying the fumonisin degrading enzyme.
The preparation method of fumonisin degrading enzyme FumDPS according to the present invention, wherein said host cell preferably is E. coli cell, Saccharomyces cerevisiae cell or Saccharomyces polymorpha cell, and more preferably is E. coli BL21strain (DE3).
The present invention also provides an application of said fumonisin degrading enzyme FumDPS, especially in the degradation of fumonisin.
The fumonisin degrading enzyme of the present invention has the optimum temperature of 37° C., the optimum pH of 8 to 9, remains more than 60% of the activity in the range of pH 3-7, and has 100% of the degradation rate of FB1 at the optimum temperature and the optimum pH.
The present invention provides a fumonisin degrading enzyme with the excellent properties, which can be used to reduce the harm of fumonisin to animals and human health in agriculture, feed and food.
Test Materials and Reagents
1. Strains and vectors: E. coli expression vector pET28a (+) and strain BL21 (DE3).
2. Medium:
E. coli LB medium: 1% peptone, 0.5% yeast extract, and 1% NaCl, pH 7.0.
The artificial nucleotide sequence of the coding region of the gene encoding the fumonisin degrading enzyme FumDPS was chemically synthesized, and was add with the the restriction enzyme sites EcoR I and Xho I in its 5 ‘end and 3’ end respectively.
The expression vector pET28a(+) and the gene encoding fumonisin degrading enzyme was digested with the restriction enzyme EcoR I and Xho I, respectively, and the obtained gene fragment encoding mature fumonisin degrading enzyme was connected with the expression vector pET28a (+) to obtain the recombinant plasmid pET28a(+)-FumDPS containing FumDPS which was transformed into strain E. coli BL21 (DE3) to obtain the recombinant strain E. coli BL21 (DE3)/FumDPSs.
The recombinant expression vector comprising the fumonisin degrading enzyme gene with signal peptide sequence was constructed by the same way.
Furthermore, the strain BL21 (DE3) comprising the recombinant plasmid was inoculated in 100 mL of LB medium, cultured by shaking at 37° C. and 220 rpm for 2 to 3 h, and add with IPTG in a final concentration of 1 mM when OD600 was 0.6 to 0.8, followed by inducing at 25° C. for 20 h, and collecting the cells by centrifugation at 4° C. The supernatant was collected after ultrasonic crushing and the protein was purified by nickel column. The results of SDS-PAGE showed that the recombinant fumonisin degrading enzyme was expressed in E. coli shown as shown by the lane 1 indicating the purified FumDPS of
The enzyme activity of the fumarotoxin degrading enzyme was detected by high performance liquid chromatography (HPLC) including the following steps of
(1) preparing FB1 standard stock solution, wherein 1 mg of standard sample, was dissolve with 10 mL of acetonitrile and water in a ratio of 1:1, to obtain the standard solution in the concentration of 100 ug/mL, being stored at −20° C.
(2) preparing sample wherein 900 ul of the purified fumonisin degrading enzyme solution was added with 100 ul of FB1 standard stock solution to 10 ug/ml of the final concentration of FB1 followed by being cultured for 20 min at 37° C. and 220 rpm in dark. and
(3) deriving the sample wherein 400 uL of acetonitrile water at the concentration of 50% was added to 100 uL of sample to obtain 500 uL of OPA derivatization solution which was mixed evenly for 30 s, and derived for 2 min followed by being loaded into the filter membrane to determine the activity of FumDPS by comparing the peak diagram with that of FB1 standard.
1. Determination of the Optimum Temperature of Fumonisin Degrading Enzyme
100 μL of FB1 as substrate was added with 900 μL of enzyme solution until the final concentration of 10 μg/mL to react for 20 min in citric acid disodium hydrogen phosphate buffer in pH7.0 at different temperatures, and then be inactivated by boiling for 10 min, followed by detecting after cooling to the room temperature and membrane filtration.
As shown in
2. Determination of the Optimum pH of Fumonisin Degrading Enzyme
The purified recombinant enzyme FumDPS was perform the enzymatic reaction to determine the optimum pH wherein the enzyme reacted with the substrate FB1 at the final concentration of 1 μg/mL min at 37° C. for 30 min in the different pH buffers, and boiled for 10 min followed by high performance liquid chromatography (HPLC), wherein the buffer gradients of the buffer solutions were 100 mM of citric acid disodium hydrogen phosphate from pH 3.0 to 8.0, 100 mM of Tris Hcl from pH 8.0 to 9.0, and 100 mM of glycine-NaOH from pH 9.0 to 12.0.
As shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 201811171693.5 | Oct 2018 | CN | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/CN2019/108923 | 9/29/2019 | WO | 00 |
