CN113913399A

CN113913399A - Ketopantolactone reductase derived from Candida maltosa Xu316

Info

Publication number: CN113913399A
Application number: CN202111408398.9A
Authority: CN
Inventors: 张光祥; 王竞辉; 李胜勇; 陈浩; 郑兵; 孙烨; 黎源
Original assignee: Wanhua Chemical Group Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd
Priority date: 2021-11-19
Filing date: 2021-11-19
Publication date: 2022-01-11
Anticipated expiration: 2041-11-19
Also published as: CN113913399B

Abstract

The invention belongs to the technical field of biocatalysis, and particularly relates to ketopantoate lactone reductase derived from Candida maltosa Xu 316. The invention provides ketopantolactone reductase derived from Candida maltosa Xu316 for the first time, which can be used for asymmetrically synthesizing a key intermediate D-pantolactone of D-calcium pantothenate, the substrate conversion rate reaches 99%, the optical purity (e.e.) of a product reaches 99%, and the space-time yield of the D-pantolactone reaches 590g L^‑1d^‑1And has good application prospect.

Description

Ketopantolactone reductase derived from Candida maltosa Xu316

Technical Field

The invention relates to the technical field of biocatalysis, in particular to ketopantoate reductase derived from Candida maltosa Xu316, encoding polynucleotide, recombinant vector and recombinant cell thereof, and a preparation method and application of the ketopantoate reductase in preparation of D-pantoate.

Background

D-pantothenic acid, also known as vitamin B5, is mainly commercially available as calcium D-pantothenate. The D-calcium pantothenate is widely applied to animal feeds, food additives and pharmaceutical raw material medicines, wherein the animal feed accounts for the largest proportion, namely 75%, and downstream requirements leading from the feed industry are relatively rigid.

D-pantoic acid lactone is a key intermediate for synthesizing D-calcium pantothenate. At present, in industrial production, D-pantoic acid lactone is mainly synthesized by isobutyraldehyde-formaldehyde-sodium cyanide method, DL-pantoic acid lactone is firstly synthesized, then D-pantoic acid lactone is selectively hydrolyzed by D-pantoic acid lactone hydrolase to obtain D-pantoic acid, D-pantoic acid and L-pantoic acid lactone are separated by solvent extraction, the separated D-pantoic acid is converted into D-pantoic acid lactone by lactonization for synthesizing D-calcium pantothenate, and L-pantoic acid lactone is subjected to chemical racemization and then participates in hydrolysis again. The resolution process of the D-pantoic acid lactone hydrolase catalyzed microbial enzyme method is mature, but the problems of complicated process route, large dosage of extraction solvent, high dosage of acid and alkali and the like exist. Therefore, the development process is simple, environment-friendly and efficient, and the asymmetric reduction route of the biological enzyme method has important significance.

Taking DL-pantolactone as a substrate, asymmetrically synthesizing D-pantolactone by an oxidation-reduction enzyme method relates to two-step enzyme catalytic reaction, wherein in the first step, L-pantolactone dehydrogenase is used for specifically oxidizing L-pantolactone in the substrate into keto-pantolactone, and in the second step, keto-pantolactone reductase is used for enantioselectively reducing the keto-pantolactone into D-pantolactone, so that the configuration inversion of the L-pantolactone is realized. The method takes racemic pantolactone as a substrate, and realizes the preparation of D-pantolactone in a green and high-efficiency manner through multi-enzyme one-pot reaction under mild reaction conditions.

The ketopantolactone reductase is a key enzyme of a process route for asymmetrically synthesizing D-pantolactone by an oxidation-reduction enzyme method, and the catalytic activity and enantioselectivity of the ketopantolactone reductase have important influences on the catalytic reaction efficiency of enzyme and the optical purity of a product. At present, the number of publicly reported ketopantolactone reductase and gene resources thereof is small, and the research on enzymology properties, the research on structure-activity relationship and the application thereof in the efficient asymmetric synthesis of D-pantolactone are limited. Kataoka, et al 2003 reported two conjugated polyketide reductases CPR-C1 and CPR-C2(Applied Microbiology and Biotechnology,2004,64: 359-. Since 2018, only 3 ketopantoate reductase enzymes for asymmetric synthesis of D-pantoate lactone have been reported in public, including CorCPR (Journal of Biotechnology 291,2019, 26-34), CduCPR (Enzyme and microbiological Technology 126,2019, 77-85) and CalCPR (CN 110452861B), wherein the catalytic reaction efficiency is highest with CduCPR, but the space-time yield is only 307.5g L^-1d^-1。

In conclusion, in the existing technical route for asymmetric synthesis of D-pantolactone by using a ketopantolactone reductase with an oxidation-reduction enzyme method, the key enzymes of ketopantolactone reductase still have the problems of lack of sources, low catalytic activity, low space-time yield of asymmetric reduction reaction and the like, so that the application of the ketopantolactone reductase in industrial scale is limited.

Disclosure of Invention

The present invention aims to provide a ketopantolactone reductase derived from Candida maltosa Xu316, which is improved in catalytic activity against ketopantolactone and in space-time yield.

In order to achieve the above object, according to a first aspect, the present invention provides a ketopantoate lactone reductase derived from Candida maltosa Xu316, the amino acid sequence of which is shown in SEQ ID NO 1.

In a second aspect, the present invention provides a polynucleotide encoding said ketopantolactone reductase, the nucleotide sequence of which is set forth in SEQ ID NO 2.

In a third aspect, the present invention provides a recombinant vector comprising a polynucleotide encoding said ketopantolactone reductase.

In some embodiments, the recombinant vector further comprises a polynucleotide encoding a glucose dehydrogenase.

In some preferred embodiments, the glucose dehydrogenase is derived from Bacillus megaterium (Bacillus megaterium) and has the amino acid sequence shown in SEQ ID NO. 3, and the nucleotide sequence of the polynucleotide encoding the glucose dehydrogenase is shown in SEQ ID NO. 4.

In a fourth aspect, the present invention provides a recombinant cell comprising the recombinant vector described above.

In some embodiments, the recombinant cell induces the ketopantolactone reductase of the invention derived from Candida maltosa Xu 316.

In some embodiments, the recombinant cell further induces production of glucose dehydrogenase.

In some preferred embodiments, the glucose dehydrogenase is derived from Bacillus megaterium, the amino acid sequence of which is set forth in SEQ ID NO. 3, and the nucleotide sequence of the polynucleotide encoding the glucose dehydrogenase is set forth in SEQ ID NO. 4.

In a fifth aspect, the present invention provides a method for preparing ketopantolactone reductase, comprising:

carrying out induction culture on the recombinant cells to obtain a culture;

isolating the ketopantolactone reductase from the culture.

In some embodiments, the method of making further comprises the step of isolating glucose dehydrogenase from the culture.

In a sixth aspect, the invention provides the use of a ketopantolactone reductase of the invention, a polynucleotide of the invention, a recombinant vector of the invention and/or a recombinant cell of the invention for the preparation of D-pantolactone.

In a seventh aspect, the present invention provides a method for preparing D-pantoic acid lactone, comprising: the ketopantolactone reductase, the recombinant cell and/or the ketopantolactone reductase prepared by the preparation method are/is used as a catalyst to perform catalytic reaction on ketopantolactone to obtain D-pantolactone.

In some embodiments, the reaction pH of the catalyzed reaction is from 6 to 8.

In some embodiments, the reaction temperature of the catalyzed reaction is from 30 ℃ to 50 ℃.

In some embodiments, the catalytic reaction is performed in a phosphate buffer.

In some embodiments, the cumulative final concentration of ketopantolactone in the catalyzed reaction is from 1mM to 400 mM.

In some embodiments, the mass ratio of the catalyst to the ketopantoic acid lactone in the catalytic reaction is (0.01-0.1): 1.

The invention provides ketopantolactone reductase derived from Candida maltosa Xu316 for the first time, which has excellent catalytic activity and enantioselectivity to ketopantolactone. The ketopantolactone reductase provided by the invention is used for asymmetrically synthesizing a key intermediate D-pantolactone of D-calcium pantothenate, the substrate conversion rate reaches 99%, the optical purity (e.e.) of a product reaches 99%, and the space-time yield of the D-pantolactone reaches 590g L^-1d^-1. Compared with the enzymatic resolution method commonly adopted in the industry at present, the ketopantoic acid lactone is utilizedThe reductase is used for producing D-pantoic acid lactone, so that the production process is simplified, the use of a large amount of organic solvent extractant and strong acid and alkali is avoided, and the method is a biological catalysis technology with wide application prospect.

Drawings

FIG. 1 is a schematic diagram of the asymmetric synthesis of D-pantolactone from ketopantolactone according to the invention, wherein CmaCPR represents ketopantolactone reductase derived from Candida maltosa Xu 316;

FIG. 2 is a graph showing an analysis of the evolutionary relationship of candidate enzymes obtained by mining genome data in example 1 of the present invention, wherein CmaCPR represents ketopantolactone reductase derived from Candida maltosa Xu 316;

FIG. 3 is a gas chromatogram of D-pantolactone in example 4 of the present invention;

FIG. 4 is a graph showing the reaction progress of the genetically engineered bacteria in example 4 of the present invention in the catalytic conversion of ketopantolactone to D-pantolactone.

Detailed Description

The embodiment of the invention provides a ketopantoate lactone reductase derived from Candida maltosa Xu316, and the amino acid sequence of the ketopantoate lactone reductase is shown as SEQ ID NO 1.

The inventor of the invention carries out high-throughput screening based on primary sequence comparison in massive gene data of a National Center of Biotechnology Information (NCBI) database by means of genome data mining to preliminarily obtain 20 candidate genes with potential catalytic performance, and then combines experimental verification screening to further obtain the ketopantolactone reductase with better catalytic performance and derived from Candida maltosa Xu 316. The ketopantolactone reductase derived from Candida maltosa Xu316 has excellent catalytic activity and enantioselectivity to ketopantolactone. When the D-pantoic acid lactone is asymmetrically synthesized, the substrate conversion rate reaches 99 percent, the optical purity (e.e.) of the product reaches 99 percent, and the space-time yield of the D-pantoic acid lactone reaches 590g L^-1d^-1。

The ketopantolactone reductase derived from Candida maltosa Xu316 provided by the embodiments of the present invention can be a naturally occurring, recombinant, or synthetic active polypeptide. The active polypeptide may be a naturally purified product, a chemically synthesized product, or a product produced by recombinant techniques from a prokaryotic host (e.g., E.coli) or a eukaryotic host (e.g., yeast, higher plants).

In some preferred embodiments, the ketopantolactone reductase derived from Candida maltosa Xu316 is obtained by:

(11) taking the sequence of ketopantolactone reductase CduCPR which is derived from Candida dubliniensis CD36 and has the best catalytic performance and is reported at present as a probe, carrying out BLAST (basic Local Alignment Search tool) in a National Center for Biotechnology Information (NCBI) database, and selecting a new enzyme resource with potential ketopantolactone reduction activity based on primary sequence Alignment (generally, the potential of similar catalytic activity to the probe is considered to be achieved when the amino acid sequence consistency exceeds 30 percent);

(12) performing sequence analysis on the new enzyme resource obtained in the step (11), and screening candidate enzymes with a characteristic fingerprint sequence (GXGTX);

(13) analyzing the evolution relation of the candidate enzyme obtained in the step (12), and screening the candidate enzyme which is closer to the evolution relation of the probe for further functional screening (taking the amino acid sequence of the enzyme protein as an index for reflecting the evolution relation, and selecting the enzyme with more than 50 percent of consistency with the amino acid sequence of the probe as the candidate enzyme which is closer to the evolution relation of the probe);

(14) designing a primer according to a gene sequence of the candidate enzyme which is closer to the probe evolution relation, and carrying out gene cloning by taking a genome of a wild bacterium in which the candidate enzyme is positioned as a template to obtain a gene fragment for coding the candidate enzyme;

(15) heterogeneously expressing the gene fragment of the candidate enzyme obtained in the step (14) in escherichia coli engineering bacteria by a genetic engineering technology;

(16) coating the engineering bacteria on a flat plate, selecting monoclone, sequencing, and selecting positive clone to transfer to a test tube for culture;

(17) the obtained bacterial solution was centrifuged to obtain wet cells, 10mL of potassium phosphate buffer (100mM, pH6.5) and 10% (w/v) of substrate ketopantolactone were added, and the reaction was carried out at 30 ℃ and 200rpm for 12 hours. Adding ethyl acetate to extract the reaction solution, sampling and analyzing the conversion rate of ketopantolactone and the optical purity of D-pantolactone.

(18) When the optical purity of D-pantolactone is 99% or more and the conversion of ketopantolactone is higher than that using the probe, the candidate enzyme is the target enzyme.

Wherein, in the step (18), the optical purity of D-pantoic acid lactone is taken as a first index, and needs to be more than 99 percent, because the lower optical purity of the product can adversely affect the purification of the final product of D-calcium pantothenate; taking the conversion (%) of ketopantolactone as a second index, under the same conditions, when the conversion of ketopantolactone by the candidate enzyme is higher, it means that the catalytic activity of the candidate enzyme is better.

The amino acid sequence of ketopantolactone reductase derived from Candida maltosa Xu316 (SEQ ID NO:1, CmaCPR):

MSTHPVKFTRSFKTKSGNELSIGTGTGTKWKKDGKIETINQELVDQILLAINSGFRHIDTAEVYNTQAEVGEAIKQSGIPREELWITTKYNPGWQTIKASSQSPKASIETALKQLGTDYIDLYLIHQPFFSEESTHGYTLEDIWKTLIDYKKQGKIREIGVSNCAIEHIEKLKAVSGSPEFYPVVNQIESHPFLQDQSRNITAYSQENDILVEAFSPLTPVSRVEKNPLTDYLDKLSEKYKKTPGQVLLRYTLQRGILPITTSAKEERIKEALDVFDFELTKE

accordingly, the nucleotide sequence of the polynucleotide encoding the ketopantolactone reductase derived from Candida maltosa Xu316 is shown in SEQ ID NO. 2.

The polynucleotide provided by the embodiments of the present invention can be obtained by PCR amplification or artificial synthesis.

A nucleotide sequence (SEQ ID NO:2) of a polynucleotide encoding a ketopantolactone reductase derived from Candida maltosa Xu 316:

atgtccacacatccagtcaaattcactagatcattcaaaaccaaatccggtaacgaattgtcaatcggtacaggtaccggtaccaaatggaaaaaagatggcaagatcgaaactatcaatcaagaattagttgaccaaatcttattagcgatcaacctgggatttagacacattgatactgccgaagtctacaacacccaagcagaagttggtgaagctatcaaacaatccggaattccaagagaagaactttggatcactaccaaatataatccaggttggcaaactatcaaagcttcaagtcaaagtcctaaagcatcgattgaaacagccttgaagcaattgggtaccgactacattgatttgtatttgatccatcaaccatttttctcggaagaatctactcacgggtacactttggaagacatctggaaaaccttaattgactataagaaacaaggcaagatcagagaaatcggggtatccaattgcgccattgaacatatcgaaaaattgaaagcggtctcaggaagtccagagttctatccagtagttaaccaaatcgaaagtcatccattcttacaagaccaatcgcgtaacattaccgcgtactctcaagaaaacgatattttggttgaagcattctcgccattgacaccagtttcccgtgttgagaagaacccattgaccgattacttggataaactttccgaaaaatacaagaagactccgggtcaagtattgttgagatacactttacaaagaggaatcttgccaatcaccacatcagctaaagaagagagaattaaagaagcattagatgtgtttgatttcgaattgaccaaagaa

embodiments of the invention also provide a recombinant vector comprising a polynucleotide encoding the ketopantolactone reductase. Specifically, the recombinant vector includes a cloning vector for replicating a relevant sequence and an expression vector for expressing a relevant gene.

In some embodiments, the recombinant vector is pACYCDuet-1 comprising a polynucleotide encoding the ketopantoate lactone reductase.

In some preferred embodiments, the recombinant vector further comprises a polynucleotide encoding a glucose dehydrogenase. The advantage is that the recombinant vector can express the ketopantolactone reductase and the glucose dehydrogenase simultaneously. Furthermore, the glucose dehydrogenase catalyzes NADP in the production of D-pantolactone by the asymmetric reduction of ketopantolactone reductase catalyzing ketopantoate⁺The reduction is NADPH, and the NADPH provides reducing power for asymmetric reduction reaction catalyzed by ketopantolactone reductase, thereby avoiding adding expensive cofactors from external sources and effectively reducing the production cost. More preferably, the glucose dehydrogenase is derived from Bacillus megaterium, the amino acid sequence of which is shown in SEQ ID NO. 3, and the nucleotide sequence of the polynucleotide encoding the glucose dehydrogenase is shown in SEQ ID NO. 4.

Amino acid sequence of glucose dehydrogenase derived from Bacillus megaterium (SEQ ID NO:3, BmGDH):

MYKDLEGKVVVITGSSTGLGKSMAIRFATEKAKVVVNYRSKEDEANSVLEEIKKVGGEAIAVKGDVTVESDVINLVQSAIKEFGKLDVMINNAGLENPVSSHEMSLSDWNKVIDTNLTGAFLGSREAIKYFVENDIKGTVINMSSVHEKIPWPLFVHYAASKGGMKLMTETLALEYAPKGIRVNNIGPGAINTPINAEKFADPEQRADVESMIPMGYIGEPEEIAAVAAWLASSEASYVTGITLFADGGMTQYPSFQAGRG

nucleotide sequence encoding a glucose dehydrogenase derived from Bacillus megaterium (SEQ ID NO: 4):

atgtataaagatttagaaggaaaagtagtggtcataacaggttcatctacaggtttgggaaaatcaatggcgattcgttttgcgacagaaaaagctaaagtagttgtgaattatcgttctaaggaagacgaagctaacagcgttttagaagaaattaaaaaagttggcggagaggctattgccgttaaaggtgacgtaacagttgagtctgatgtaatcaatttagttcaatctgcaattaaagaatttggaaagttagacgtcatgattaataacgcaggactagaaaatccggtttcatctcatgaaatgtctttaagcgattggaataaagtaattgatacgaacttaacgggagctttcttaggtagccgtgaagcgattaaatattttgttgaaaatgatattaagggaacagttattaacatgtcgagtgttcacgagaaaattccttggccattatttgttcattatgcagcaagtaaaggcggtatgaagcttatgactgaaacactggcattagaatacgctccaaaaggtattcgtgtaaataacattggaccgggagcgattaatacaccgattaacgctgagaaatttgctgatcctgagcagcgtgcagatgtagaaagcatgattccaatgggatacatcggagagccggaagaaattgcagcagttgctgcatggctagcttcttcagaggcgagttatgtaacaggaattacgctctttgctgacggcggtatgacacagtacccatcattccaagcaggacgcggataa

in some preferred embodiments, the recombinant vector is constructed as follows:

the recombinant vector pACYCDuet-1-CmaCPR-BmGDH is obtained by taking pACYCDuet-1 as a vector plasmid, inserting a ketopantoate reductase CmaCPR gene derived from Candida maltosa Xu316 between NcoI and NotI enzyme cutting sites of a first group of multiple cloning sites, and inserting a glucose dehydrogenase BmGDH gene derived from Bacillus megaterium between BglII and PacI enzyme cutting sites of a second group of multiple cloning sites.

The embodiment of the invention also provides a recombinant cell, which comprises the recombinant vector.

In some preferred embodiments, the recombinant cell induces the ketopantolactone reductase of the invention derived from Candida maltosa Xu 316. Further, the recombinant cell also induces production of glucose dehydrogenase. Furthermore, the glucose dehydrogenase is derived from Bacillus megaterium, the amino acid sequence of the glucose dehydrogenase is shown as SEQ ID NO. 3, and the nucleotide sequence of the polynucleotide encoding the glucose dehydrogenase is shown as SEQ ID NO. 4.

In some preferred embodiments, the recombinant cell is constructed as follows:

the recombinant vector is transformed into a host cell, and the host cell is induced to obtain a recombinant cell expressing ketopantolactone reductase derived from Candida maltosa Xu 316.

Further, the recombinant vector is a recombinant vector pACYCDuet-1-CmaCPR-BmGDH, and the host cell is a prokaryotic cell or a eukaryotic cell, such as Escherichia coli, yeast and the like, preferably a genetically engineered bacterium Escherichia coli E.coli BL21(DE 3). The recombinant vector pACYCDuet-1-CmaCPR-BmGDH is transformed into E.coli BL21(DE3), and an engineering bacterium (recombinant cell) which simultaneously expresses ketopantolactone reductase derived from Candida maltosa Xu316 and glucose dehydrogenase derived from Bacillus megaterium is obtained after induction.

The embodiment of the invention also provides a preparation method of the ketopantolactone reductase, which comprises the following steps:

(21) carrying out induction culture on the recombinant cells to obtain a culture;

(22) isolating the ketopantolactone reductase from the culture.

In some preferred embodiments, the step (22) further comprises isolating glucose dehydrogenase from the culture. Among them, a method of inducing culture of recombinant cells, a method of isolating ketopantolactone reductase from the culture, and a method of isolating glucose dehydrogenase from the culture are conventional in the art.

The ketopantolactone reductase derived from Candida maltosa Xu316 provided by the embodiments of the present invention, the polynucleotide of the present invention, the recombinant vector of the present invention, and/or the recombinant cell of the present invention can be used for producing D-pantolactone. In particular, the ketopantolactone reductase derived from Candida maltosa Xu316, the polynucleotide of the invention, the recombinant vector of the invention and/or the recombinant cell of the invention described above is used to catalyze the asymmetric synthesis of D-pantolactone.

The embodiment of the invention also provides a preparation method of D-pantoic acid lactone, which comprises the following steps: the ketopantolactone reductase derived from Candida maltosa Xu316, the recombinant cell and/or the ketopantolactone reductase prepared by the preparation method are/is used as a catalyst to perform catalytic reaction on ketopantolactone to obtain D-pantolactone. The reaction principle involved in the preparation method of the D-pantolactone is shown in figure 1, ketopantolactone is used as a substrate, and glucose is used as a co-substrate.

In some preferred embodiments, the D-pantoic acid lactone is prepared as follows:

the recombinant cell expressing ketopantolactone reductase derived from Candida maltosa Xu316 and glucose dehydrogenase derived from Bacillus megaterium is contacted with a substrate ketopantolactone to carry out an asymmetric reduction reaction, and the produced D-pantolactone is collected from the reaction product.

The loading on the substrate (i.e., the concentration of substrate in the reaction system) is a key performance indicator characterizing the enzyme-catalyzed reaction. Under otherwise identical conditions, higher substrate loading means that the enzyme-catalyzed reaction is more efficient, and higher product titers (i.e., product concentrations) and higher space-time yields are advantageously achieved. However, too high a substrate concentration leads to the accumulation of ketopantolactone which is not completely converted, and its spontaneous hydrolysis both leads to waste of raw materials and adversely affects the product purity. Thus, in some preferred embodiments, the cumulative final concentration of the substrate ketopantolactone is from 1 to 400 mM.

In some preferred embodiments, glucose is used as a reaction co-substrate, which functions to regenerate the cofactor NADPH and to push the main reaction forward, and is added in an amount of 1.1 to 1.5 equivalents, i.e., 440 to 600mM, preferably 440mM, to the substrate ketopantolactone. The addition amount can ensure the reaction effect and simultaneously generate less byproduct sodium gluconate, thereby reducing the burden of subsequent separation and purification.

In some preferred embodiments, the catalyst is used in an amount of 0.01 to 0.1 g of cells per g of ketopantolactone, based on the mass of the substrate ketopantolactone.

In some preferred embodiments, the reaction is performed in a phosphate buffer.

In some preferred embodiments, the reaction temperature is 30 to 50 ℃.

In some preferred embodiments, the pH of the reaction system is 6.0-8.0, and the pH can be adjusted by dropwise adding an alkali solution (such as sodium carbonate).

In some preferred embodiments, the catalyst comprises any one of the following forms:

(i) collecting wet bacteria by centrifugation or filtration, which express ketopantolactone reductase derived from Candida maltosa Xu316 and glucose dehydrogenase derived from Bacillus megaterium;

(ii) crushing wet thalli by grinding or homogenizing and the like, and extracting the obtained cell-free extract by using water or buffer solution;

(iii) treating the cell-free extract with a suitable method, including but not limited to affinity chromatography, etc.;

(iv) the immobilized cells or enzymes obtained from the material containing the above active enzyme component (i.e., the recombinant engineered bacteria, the wet cells, the cell-free extract and/or the pure enzyme) are treated by a suitable method, including but not limited to carrier adsorption, glutaraldehyde crosslinking, gel embedding, etc.

The substrate ketopantoic acid lactone is extremely easy to hydrolyze, and in order to reduce the spontaneous hydrolysis of the substrate in the catalysis process, the addition of the substrate and the auxiliary substrate preferably adopts a fed-batch mode, so that the cumulative concentration of the ketopantoic acid lactone in a reaction system is continuously increased, and the spontaneous hydrolysis caused by the accumulation of the high-concentration ketopantoic acid lactone and the inhibition effect on the activity of the catalyst are avoided.

In order to make the above-mentioned details and operations of the present invention clearly understood by those skilled in the art and to make the progress of ketopantoate lactone reductase and its preparation and application obvious, the above-mentioned technical solutions are illustrated by the following examples.

The experimental procedures, for which specific conditions are not specified in the examples below, are generally carried out according to the methods customary in the field of Molecular Biology, including, but not limited to, those described in Molecular Cloning Manual, Molecular Biology, and the like, by M.R. Green, or according to the protocols recommended by manufacturers of kits and instruments. Reagents and biomaterials used in the examples were commercially available without specific reference.

Example 1 screening of ketopantolactone reductase

The most catalytically active reductase which has been reported to catalyze the asymmetric reduction of ketopantolactone to D-pantolactone is CduCPR from Candida dubliniensis CD36, the amino acid sequence of which is retrieved from the National Center for Biotechnology Information (NCBI) database under GenBank accession number CCG 25060.1. Using the amino acid sequence of the obtained CduCPR as a probe, performing BLAST (basic Local Alignment Search tool) in NCBI database, and selecting new enzyme resources with potential ketopantoic acid lactone reduction activity based on primary sequence Alignment. The new enzyme resource obtained as above was subjected to sequence analysis using BioEdit, and candidate enzymes having a D-pantolactone reductase-characteristic fingerprint sequence (GXGTX) were screened. The new enzyme obtained as described above was subjected to evolutionary analysis using MEGA, and candidate enzymes closer to the probe CduCPR in evolutionary relationship were screened (FIG. 2). Designing PCR primers according to the gene sequence of the candidate enzyme, and carrying out gene cloning by taking the genome of the wild strain in which the candidate enzyme is positioned as a template to obtain a gene fragment for coding the candidate enzyme. Through gene engineering technology, the gene fragment of the candidate enzyme is heterologously expressed in the escherichia coli engineering bacteria. Coating the engineering bacteria on a flat plate, selecting monoclone, sequencing, and selecting positive clone to transfer to a test tube for culture. The obtained bacterial solution was centrifuged to obtain wet cells, 10mL of potassium phosphate buffer (100mM, pH6.5) and 10% (w/v) of substrate ketopantolactone were added, and the reaction was carried out at 30 ℃ and 200rpm for 12 hours. Ethyl acetate was added to extract the reaction solution, and the conversion of ketopantolactone and the optical purity of D-pantolactone were sampled and analyzed, and the results are shown in Table 1.

TABLE 1 screening of ketopantolactone reductase function

Enzyme	Source	Conversion (%)	e.e.(％)	Product configuration
					CviCPR	Candida viswanathii	>99	>99	R
CmaCPR	Candida maltosa Xu316	>99	>99	R
					CduCPR	Candida dubliniensis CD36	60	99	R
CorCPR	Candida orthopsilosis Co 90-125	58	99	R
					SpaCPR-1	Spathaspora passalidarum NRRL Y-27907	57	78	R
SstCPR	Scheffersomyces stipitis CBS 6054	50	89	R
					MafCPR	Metschnikowia aff.pulcherrima	48	88	S
HbuCPR-1	Hyphopichia burtonii NRRL Y-1933	47	98	R
					SpaCPR-2	Spathaspora passalidarum NRRL Y-27907	42	99	R
SliCPR	Sugiyamaella lignohabitans	40	57	R
					WciCPR-1	Wickerhamomyces ciferrii	37	87	R
WciCPR-2	Wickerhamomyces ciferrii	37	78	R
					HbuCPR-2	Hyphopichia burtonii NRRL Y-1933	35	88	S
HguCPR	Hanseniaspora guilliermondii	31	90	R
					AseCPR	Aspergillus sergii	29	74	R
TmaCPR	Talaromyces marneffei ATCC 18224	29	65	R
					CjaCPR	Cyberlindnera jadinii NRRL Y-1542	22	90	S
MbiCPR	Metschnikowia bicuspidata	22	95	S
					TtoCPR	Trichophyton tonsurans CBS 112818	18	95	S
CpoCPR	Coccidioides posadasii str.Silveira	15	96	S
					TruCPR	Trichophyton rubrum CBS 118892	10	61	R

As can be seen from Table 1, the ketopantolactone reductase CmaCPR derived from Candida maltosa Xu316 can efficiently and stereospecifically asymmetrically reduce a substrate ketopantolactone to D-pantolactone, and the conversion rate and the optical purity of the catalytic reaction are remarkably superior to those of a probe CduCPR.

Example 2 construction of recombinant plasmid CmaCPR ketopantolactone reductase

The wild strain Candida maltosa Xu316 was cultured and the genome thereof was obtained by a genome extraction kit. Primers (see table 2) were designed using Candida maltosa Xu316 genome as a template for Polymerase Chain Reaction (PCR), and the gene encoding ketopantolactone reductase CmaCPR was obtained by gene cloning. Glucose dehydrogenase BmGDH derived from Bacillus megaterium was cloned in the same manner.

TABLE 2 Gene cloning primers for ketopantolactone reductase and glucose dehydrogenase

Primer name	Sequence numbering	Primer sequence (5 '→ 3')
			CmaCPR-FP	SEQ ID NO:5	atgtccacacatccagtcaaattcactaga
CmaCPR-RP	SEQ ID NO:6	ttctttggtcaattcgaaatcaaacacatc
			BmGDH-FP	SEQ ID NO:7	atgtataaagatttagaaggaaaagtagtg
BmGDH-RP	SEQ ID NO:8	ttatccgcgtcctgcttggaatgatgggta

The recombinant plasmid pACYCDuet-1-CmaCPR-BmGDH co-expressing ketopantolactone reductase CmaCPR and glucose dehydrogenase BmGDH is obtained by taking pACYCDuet-1 as a vector plasmid, inserting the ketopantolactone reductase CmaCPR gene derived from Candida maltosa Xu316 obtained in the way into the NcoI and NotI enzyme cutting sites of a first group of multiple cloning sites, inserting the glucose dehydrogenase BmGDH gene derived from Bacillus megaterium obtained in the way into the BglII of a second group of multiple cloning sites and into the PacI enzyme cutting sites.

Example 3 construction of engineering bacteria for heterologous expression of ketopantolactone reductase CmaCPR

Escherichia coli E.coli BL21(DE3) is used as an expression host, the obtained recombinant expression plasmid pACYCDuet-1-CmaCPR-BmGDH is transformed into Escherichia coli E.coli BL21(DE3) by a chemical method, and engineering bacteria which simultaneously express ketopantolactone reductase derived from Candida maltosa Xu316 and glucose dehydrogenase derived from Bacillus megaterium are obtained after induction.

Example 4 Synthesis of D-pantolactone from ketopantolactone by catalysis of genetically engineered bacterium E

The obtained genetically engineered bacterium E.coli co-expressing ketopantolactone reductase CmaCPR and glucose dehydrogenase BmGDH was added to potassium phosphate buffer (100mM, pH6.5) to make the wet cell concentration to 5.1g/L, and the reaction was carried out by continuously feeding buffer containing substrates ketopantolactone and glucose at 30 ℃ and 200rpm,feedback adjustment of Na by on-line monitoring of pH₂CO₃The pH was controlled to about 6.5. Sampling is carried out at intervals in the reaction process, the reaction solution is extracted by using ethyl acetate, and the concentration of the ketopantoic acid lactone as a substrate and the optical purity of the D-pantoic acid lactone as a product are analyzed in a gas phase, so as to obtain a reaction progress curve (figure 4).

The gas chromatography (SHIMADZU GC2030) analysis and detection method of the substrate keto-pantoic acid lactone, the product D-pantoic acid lactone and the isomer L-pantoic acid lactone thereof is as follows: the chromatographic column is BGB-174(30m is multiplied by 250 μm is multiplied by 0.25 μm), the FID detector (250 ℃), nitrogen is used as carrier gas (30mL/min), hydrogen is 40mL/min, the sample injection amount is 1 μ L, the split ratio is 30:1, the sample injection port is 250 ℃, and the column temperature is 175 ℃ and is maintained for 8 min. Under the analysis condition, the retention time of the keto-pantolactone, the D-pantolactone and the L-pantolactone is 6.397min, 5.983min and 6.116min respectively. The results of the detection are shown in FIG. 3.

After the reaction is finished for 2.1h, the cumulative adding concentration of the substrate ketopantolactone reaches 400mM, and as can be seen from the combination of the graph in FIGS. 3 and 4, no chromatographic peak is detected at the position of 6.397min of the retention time of the substrate ketopantolactone, the substrate ketopantolactone is considered to be basically and completely converted into the D-pantolactone, the substrate conversion rate is more than or equal to 99 percent, the optical purity (e.e.) of the D-pantolactone reaches 99 percent, and the space-time yield of the D-pantolactone is 590-590 g L percent by calculation^-1d^-1。

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Sequence listing

<110> Wanhua chemical group, Ltd

<120> ketopantolactone reductase derived from Candida maltosa Xu316

<130> DSP1F213648ZX

<160> 8

<170> PatentIn version 3.5

<210> 1

<211> 283

<212> PRT

<213> Candida maltosa (Candida maltosa Xu316)

<400> 1

Met Ser Thr His Pro Val Lys Phe Thr Arg Ser Phe Lys Thr Lys Ser

1 5 10 15

Gly Asn Glu Leu Ser Ile Gly Thr Gly Thr Gly Thr Lys Trp Lys Lys

20 25 30

Asp Gly Lys Ile Glu Thr Ile Asn Gln Glu Leu Val Asp Gln Ile Leu

35 40 45

Leu Ala Ile Asn Ser Gly Phe Arg His Ile Asp Thr Ala Glu Val Tyr

50 55 60

Asn Thr Gln Ala Glu Val Gly Glu Ala Ile Lys Gln Ser Gly Ile Pro

65 70 75 80

Arg Glu Glu Leu Trp Ile Thr Thr Lys Tyr Asn Pro Gly Trp Gln Thr

85 90 95

Ile Lys Ala Ser Ser Gln Ser Pro Lys Ala Ser Ile Glu Thr Ala Leu

100 105 110

Lys Gln Leu Gly Thr Asp Tyr Ile Asp Leu Tyr Leu Ile His Gln Pro

115 120 125

Phe Phe Ser Glu Glu Ser Thr His Gly Tyr Thr Leu Glu Asp Ile Trp

130 135 140

Lys Thr Leu Ile Asp Tyr Lys Lys Gln Gly Lys Ile Arg Glu Ile Gly

145 150 155 160

Val Ser Asn Cys Ala Ile Glu His Ile Glu Lys Leu Lys Ala Val Ser

165 170 175

Gly Ser Pro Glu Phe Tyr Pro Val Val Asn Gln Ile Glu Ser His Pro

180 185 190

Phe Leu Gln Asp Gln Ser Arg Asn Ile Thr Ala Tyr Ser Gln Glu Asn

195 200 205

Asp Ile Leu Val Glu Ala Phe Ser Pro Leu Thr Pro Val Ser Arg Val

210 215 220

Glu Lys Asn Pro Leu Thr Asp Tyr Leu Asp Lys Leu Ser Glu Lys Tyr

225 230 235 240

Lys Lys Thr Pro Gly Gln Val Leu Leu Arg Tyr Thr Leu Gln Arg Gly

245 250 255

Ile Leu Pro Ile Thr Thr Ser Ala Lys Glu Glu Arg Ile Lys Glu Ala

260 265 270

Leu Asp Val Phe Asp Phe Glu Leu Thr Lys Glu

275 280

<210> 2

<211> 849

<212> DNA

<213> Candida maltosa (Candida maltosa Xu316)

<400> 2

atgtccacac atccagtcaa attcactaga tcattcaaaa ccaaatccgg taacgaattg 60

tcaatcggta caggtaccgg taccaaatgg aaaaaagatg gcaagatcga aactatcaat 120

caagaattag ttgaccaaat cttattagcg atcaacctgg gatttagaca cattgatact 180

gccgaagtct acaacaccca agcagaagtt ggtgaagcta tcaaacaatc cggaattcca 240

agagaagaac tttggatcac taccaaatat aatccaggtt ggcaaactat caaagcttca 300

agtcaaagtc ctaaagcatc gattgaaaca gccttgaagc aattgggtac cgactacatt 360

gatttgtatt tgatccatca accatttttc tcggaagaat ctactcacgg gtacactttg 420

gaagacatct ggaaaacctt aattgactat aagaaacaag gcaagatcag agaaatcggg 480

gtatccaatt gcgccattga acatatcgaa aaattgaaag cggtctcagg aagtccagag 540

ttctatccag tagttaacca aatcgaaagt catccattct tacaagacca atcgcgtaac 600

attaccgcgt actctcaaga aaacgatatt ttggttgaag cattctcgcc attgacacca 660

gtttcccgtg ttgagaagaa cccattgacc gattacttgg ataaactttc cgaaaaatac 720

aagaagactc cgggtcaagt attgttgaga tacactttac aaagaggaat cttgccaatc 780

accacatcag ctaaagaaga gagaattaaa gaagcattag atgtgtttga tttcgaattg 840

accaaagaa 849

<210> 3

<211> 261

<212> PRT

<213> Bacillus megaterium (Bacillus megaterium)

<400> 3

Met Tyr Lys Asp Leu Glu Gly Lys Val Val Val Ile Thr Gly Ser Ser

1 5 10 15

Thr Gly Leu Gly Lys Ser Met Ala Ile Arg Phe Ala Thr Glu Lys Ala

20 25 30

Lys Val Val Val Asn Tyr Arg Ser Lys Glu Asp Glu Ala Asn Ser Val

35 40 45

Leu Glu Glu Ile Lys Lys Val Gly Gly Glu Ala Ile Ala Val Lys Gly

50 55 60

Asp Val Thr Val Glu Ser Asp Val Ile Asn Leu Val Gln Ser Ala Ile

65 70 75 80

Lys Glu Phe Gly Lys Leu Asp Val Met Ile Asn Asn Ala Gly Leu Glu

85 90 95

Asn Pro Val Ser Ser His Glu Met Ser Leu Ser Asp Trp Asn Lys Val

100 105 110

Ile Asp Thr Asn Leu Thr Gly Ala Phe Leu Gly Ser Arg Glu Ala Ile

115 120 125

Lys Tyr Phe Val Glu Asn Asp Ile Lys Gly Thr Val Ile Asn Met Ser

130 135 140

Ser Val His Glu Lys Ile Pro Trp Pro Leu Phe Val His Tyr Ala Ala

145 150 155 160

Ser Lys Gly Gly Met Lys Leu Met Thr Glu Thr Leu Ala Leu Glu Tyr

165 170 175

Ala Pro Lys Gly Ile Arg Val Asn Asn Ile Gly Pro Gly Ala Ile Asn

180 185 190

Thr Pro Ile Asn Ala Glu Lys Phe Ala Asp Pro Glu Gln Arg Ala Asp

195 200 205

Val Glu Ser Met Ile Pro Met Gly Tyr Ile Gly Glu Pro Glu Glu Ile

210 215 220

Ala Ala Val Ala Ala Trp Leu Ala Ser Ser Glu Ala Ser Tyr Val Thr

225 230 235 240

Gly Ile Thr Leu Phe Ala Asp Gly Gly Met Thr Gln Tyr Pro Ser Phe

245 250 255

Gln Ala Gly Arg Gly

260

<210> 4

<211> 786

<212> DNA

<213> Bacillus megaterium (Bacillus megaterium)

<400> 4

atgtataaag atttagaagg aaaagtagtg gtcataacag gttcatctac aggtttggga 60

aaatcaatgg cgattcgttt tgcgacagaa aaagctaaag tagttgtgaa ttatcgttct 120

aaggaagacg aagctaacag cgttttagaa gaaattaaaa aagttggcgg agaggctatt 180

gccgttaaag gtgacgtaac agttgagtct gatgtaatca atttagttca atctgcaatt 240

aaagaatttg gaaagttaga cgtcatgatt aataacgcag gactagaaaa tccggtttca 300

tctcatgaaa tgtctttaag cgattggaat aaagtaattg atacgaactt aacgggagct 360

ttcttaggta gccgtgaagc gattaaatat tttgttgaaa atgatattaa gggaacagtt 420

attaacatgt cgagtgttca cgagaaaatt ccttggccat tatttgttca ttatgcagca 480

agtaaaggcg gtatgaagct tatgactgaa acactggcat tagaatacgc tccaaaaggt 540

attcgtgtaa ataacattgg accgggagcg attaatacac cgattaacgc tgagaaattt 600

gctgatcctg agcagcgtgc agatgtagaa agcatgattc caatgggata catcggagag 660

ccggaagaaa ttgcagcagt tgctgcatgg ctagcttctt cagaggcgag ttatgtaaca 720

ggaattacgc tctttgctga cggcggtatg acacagtacc catcattcca agcaggacgc 780

ggataa 786

<210> 5

<211> 30

<212> DNA

<213> Artificial sequence

<220>

<223> CmaCPR-FP

<400> 5

atgtccacac atccagtcaa attcactaga 30

<210> 6

<211> 30

<212> DNA

<213> Artificial sequence

<220>

<223> CmaCPR-RP

<400> 6

ttctttggtc aattcgaaat caaacacatc 30

<210> 7

<211> 30

<212> DNA

<213> Artificial sequence

<220>

<223> BmGDH-FP

<400> 7

atgtataaag atttagaagg aaaagtagtg 30

<210> 8

<211> 30

<212> DNA

<213> Artificial sequence

<220>

<223> BmGDH-RP

<400> 8

ttatccgcgt cctgcttgga atgatgggta 30

Claims

1. A ketopantolactone reductase derived from Candida maltosa Xu316, characterized in that the amino acid sequence of said ketopantolactone reductase is represented by SEQ ID NO 1.

2. A polynucleotide encoding the ketopantolactone reductase of claim 1, wherein the nucleotide sequence of the polynucleotide is set forth in SEQ ID NO 2.

3. A recombinant vector comprising the polynucleotide of claim 2; preferably, the recombinant vector further comprises a polynucleotide encoding glucose dehydrogenase; more preferably, the glucose dehydrogenase is derived from Bacillus megaterium, the amino acid sequence of which is shown in SEQ ID NO. 3, and the nucleotide sequence of the polynucleotide encoding the glucose dehydrogenase is shown in SEQ ID NO. 4.

4. A recombinant cell comprising the recombinant vector of claim 3; preferably, the recombinant cell induces the production of a ketopantolactone reductase of claim 1; more preferably, the recombinant cell also induces the production of glucose dehydrogenase.

5. A method for preparing ketopantoate lactone reductase, comprising:

inducing and culturing the recombinant cell of claim 4 to obtain a culture;

isolating the ketopantolactone reductase from the culture.

6. The method according to claim 5, further comprising a step of isolating glucose dehydrogenase from the culture.

7. Use of the ketopantolactone reductase of claim 1, the polynucleotide of claim 2, the recombinant vector of claim 3 and/or the recombinant cell of claim 4 for the preparation of D-pantolactone.

8. A method for preparing D-pantoic acid lactone, which is characterized by comprising the following steps: the ketopantolactone reductase according to claim 1, the recombinant cell according to claim 4 and/or the ketopantolactone reductase produced by the production method according to claims 5 to 6 is used as a catalyst to catalyze a reaction of ketopantolactone to produce D-pantolactone.

9. The method according to claim 8, wherein the reaction pH of the catalytic reaction is 6 to 8; and/or

The reaction temperature of the catalytic reaction is 30-50 ℃.

10. The method of claim 8 or 9, wherein the catalytic reaction is carried out in a phosphate buffer; and/or

In the catalytic reaction, the cumulative final concentration of the ketopantoic acid lactone is 1mM-400 mM; and/or

In the catalytic reaction, the mass ratio of the catalyst to the ketopantoic acid lactone is (0.01-0.1): 1.