WO2020063268A1 - 植酸酶突变体 - Google Patents

植酸酶突变体 Download PDF

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WO2020063268A1
WO2020063268A1 PCT/CN2019/104088 CN2019104088W WO2020063268A1 WO 2020063268 A1 WO2020063268 A1 WO 2020063268A1 CN 2019104088 W CN2019104088 W CN 2019104088W WO 2020063268 A1 WO2020063268 A1 WO 2020063268A1
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phytase
mutant
amino acid
present
substitution
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PCT/CN2019/104088
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English (en)
French (fr)
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黄亦钧
张霞
程斯达
康丽华
李宾
吴秀秀
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青岛蔚蓝生物集团有限公司
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    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N9/00—Enzymes; Proenzymes; Compositions thereof; Processes for preparing, activating, inhibiting, separating or purifying enzymes
    • C12N9/14—Hydrolases (3)
    • C12N9/16—Hydrolases (3) acting on ester bonds (3.1)

Definitions

  • the invention relates to the field of biotechnology, in particular to a phytase mutant, a preparation method and application thereof, a DNA molecule encoding a phytase mutant, a vector, and a host cell.
  • Phytase is a kind of phosphatase that can hydrolyze phytic acid. It can degrade phytate phosphorus (inositol hexaphosphate) into inositol and inorganic phosphoric acid. This enzyme is divided into two categories: 3-phytase (EC.3.1.3.8) and 6-phytase (EC.3.1.2.6). Phytase is widely present in plants, animals, and microorganisms, such as higher plants such as corn and wheat, prokaryotic microorganisms such as Bacillus subtilis, Pseudomonas, lactobacillus, and E. coli, and eukaryotic microorganisms such as yeast, rhizopus, and aspergillus .
  • 3-phytase EC.3.1.3.8
  • 6-phytase EC.3.1.2.6
  • Phytase is widely present in plants, animals, and microorganisms, such as higher plants such
  • the basic storage form of phosphorus is phosphorus phytate, whose content is as high as 1% to 3%, which accounts for 60% to 80% of the total phosphorus in plants.
  • the phosphorus in the form of phytate is difficult to use due to the lack of enzymes that can decompose phytic acid in monogastric animals. Its utilization rate is only 0% to 40%, which causes many problems: First, it causes waste of phosphorus sources.
  • the phosphorus source in the feed cannot be effectively utilized; on the other hand, in order to meet the animal's demand for phosphorus, inorganic phosphorus must be added to the feed, which increases the cost of the feed; secondly, the formation of high-phosphorus feces pollutes the environment. About 85% of the phytate phosphorus in the feed will be directly excreted by animals, and a large amount of phytate in the feces will seriously pollute the water and soil.
  • phytate is an anti-nutritional factor. It can synthesize with a variety of metal ions such as Zn 2+ , Ca 2+ , Cu 2+ , Fe 2+ and protein chelation during digestion and absorption in the gastrointestinal tract of animals. Corresponding insoluble complexes reduce the effective use of these nutrients by animals.
  • Phytase can be used as a feed additive for monogastric animals, and its feeding effect has been confirmed worldwide. It can increase the utilization rate of phosphorus in plant-based feed by 60%, reduce the excretion of phosphorus in feces by 40%, and reduce the anti-nutritional effect of phytic acid. Therefore, the addition of phytase to the feed is of great significance to improve the production efficiency of the livestock and poultry industry and reduce the environmental pollution caused by phytate phosphorus.
  • phytase There are two types of phytase currently produced industrially: fungal phytase derived from Aspergillus niger and bacterial phytase derived from E. coli.
  • fungal phytase derived from Aspergillus niger and bacterial phytase derived from E. coli.
  • the phytase APPA derived from E. coli has high specific activity and good digestive tract stability. At present, it is mainly applied in the feed industry by the method of directly adding powder feed or spraying after pellet feed.
  • Bacterial phytase APPA has poor thermal stability. Its aqueous solution is incubated at 70 ° C for 5 minutes and the residual enzyme activity is less than 30%. The enzyme activity is generally less than 20% after being directly added to animal feed for granulation. The use of acid enzymes in pelleted feed is limited. The method of spraying the phytase liquid onto the feed after pelleting the feed not only increases equipment investment, but also cannot guarantee the stability of the enzyme preparation and the uniformity of the distribution in the feed. Therefore, improving thermal stability has important practical significance for current phytase for feed.
  • the present invention provides a phytase mutant, obtains the mutant protein, and improves its heat resistance, thereby facilitating the wide application of phytase in the field of feed.
  • the present invention provides a phytase mutant having any one of the amino acid sequences shown in (I), (II) or (III):
  • the substitution is a substitution of 1, 2, 3, 4, 5, 6, 7, 8, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25 amino acids.
  • the amino acid sequence of the phytase mutant has a sequence that has at least 95% homology with the amino acid sequence of the phytase.
  • the amino acid sequence of the phytase mutant has a sequence having at least 96% homology with the amino acid sequence of the phytase.
  • the amino acid sequence of the phytase mutant has a sequence having at least 97% homology with the amino acid sequence of the phytase.
  • the amino acid sequence of the phytase mutant has a sequence having at least 98% homology with the amino acid sequence of the phytase.
  • the amino acid sequence of the phytase mutant has a sequence having at least 99% homology with the amino acid sequence of the phytase.
  • the modification includes amidation, phosphorylation, methylation, acetylation, ubiquitination, glycosylation or carbonylation.
  • the substitution is a substitution of 18, 19, 20, 21, 22, 23, 24, or 25 amino acids.
  • the substitution is the 29th, 35th, 46th, 62nd, 70th, 73rd, 75th, 80th, 114th, 117th, 137th, 142th, 146th, 159th, 161th, 176th, 180th, 187th, 211th, 214th, 253th, 255th
  • One or more amino acids in position 260, 327, or 380 are substituted.
  • the substitution is 46th, 62nd, 70th, 73rd, 75th, 80th, 114th, 137th, 142th,
  • the amino acids at positions 146, 159, 161, 176, 187, 211, 255, and 380 are substituted.
  • the phytase has an amino acid sequence as shown in SEQ ID NO: 1, and one of the nucleotide sequences encoding the phytase is shown as SEQ ID NO: 2.
  • the amino acid at substitution 46 of the phytase having the amino acid sequence of SEQ ID NO: 1 is changed from Trp to Glu, and the amino acid at position 62 is changed from Gln to Trp at position 70.
  • amino acid sequence of the phytase mutant is shown in SEQ ID NO: 3, and one of the encoded nucleotide sequences is shown in SEQ ID NO: 4.
  • the present invention also includes a plasmid carrying a phytase mutant gene having a coding sequence of SEQ ID NO: 4.
  • the substitution further includes one or more of 29th, 35th, 117th, 180th, 214th, 253th, 260th, or 327th Amino acids were substituted.
  • the substitution is selected from the substitution of at least one amino acid in the group: M29A, D35Y, D117Y, K180N, A214H, Q253V, T260H or T327Y.
  • substitution or combination of substitutions contained in the mutant is selected from the following substitutions and combinations of substitutions:
  • the present invention also relates to a DNA molecule encoding the aforementioned phytase mutant.
  • the present invention also relates to a recombinant expression vector comprising the aforementioned DNA molecule.
  • the invention also relates to a host cell comprising the above-mentioned recombinant expression vector.
  • the above plasmid was transferred into host cells, and the heat resistance of the recombinantly expressed phytase mutant was significantly improved.
  • the present invention also provides a method for preparing the phytase mutant, including:
  • Step 1 Obtain a DNA molecule encoding any one of the amino acid sequences shown in (I), (II), or (III):
  • substitution is to replace 1, 2, 3, 4, 5, 6, 6, 7, 8, 9, 10, 11, 12, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24 or 25 amino acids;
  • Step 2 Fusion the DNA molecule obtained in step 1 with an expression vector to construct a recombinant expression vector and transform the host cell;
  • Step 3 The host cell containing the recombinant expression vector is induced to express the fusion protein, and the expressed fusion protein is isolated and purified.
  • the modification in the preparation method includes amidation, phosphorylation, methylation, acetylation, ubiquitination, glycosylation, or carbonylation.
  • the substitution in the preparation method is the 29th, 35th, 46th, 62nd, 70th, 73rd, 75th, 80th, 114th No. 117, No. 137, No. 142, No. 146, No. 159, No. 161, No. 176, No. 180, No. 187, No. 211, No. 214, No. 253, One or more amino acids at positions 255, 260, 327, or 380 are substituted.
  • the substitution is 46th, 62nd, 70th, 73rd, 75th, 80th, 114th, 137th, 142th,
  • the amino acids at positions 146, 159, 161, 176, 187, 211, 255, and 380 are substituted.
  • the substitution in the preparation method further includes the 29th, 35th, 117th, 180th, 214th, 253th, 260th, or 327th
  • One or more amino acids are substituted.
  • the substitution is selected from the substitution of at least one amino acid in the group: M29A, D35Y, D117Y, K180N, A214H, Q253V, T260H or T327Y.
  • the invention also provides the application of the phytase mutant in feed.
  • the present invention provides a mutant comprising at least one mutation site in M29A, D35Y, D117Y, K180N, A214H, Q253V, T260H or T327Y, and its heat resistance is significantly improved.
  • the residual activity of the mutant was 71% -95%, which was 11% -48% higher than that of phytase Phy7.2.
  • the mutant The residual rate of enzyme activity was 42% -57%, which was 8% -41% higher than that of phytase Phy7.2, and unexpected technical effects were obtained.
  • the phytase mutant provided by the present invention can be widely used in the field of feed.
  • the invention discloses a phytase mutant, and those skilled in the art can learn from the content of this article and appropriately improve the process parameters for implementation.
  • all similar replacements and modifications will be apparent to those skilled in the art, and they are all considered to be included in the present invention.
  • the method and application of the present invention have been described through the preferred embodiments. It is obvious that relevant persons can modify or appropriately modify and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention, to achieve and Apply the technology of the present invention.
  • the raw materials and reagents used in the phytase mutant provided by the present invention can be purchased from the market.
  • the applicant carried out 17 positions on the basis of the wild-type phytase APPA ((the amino acid sequence is SEQ ID NO: 1 and its coding nucleotide sequence is SEQ ID NO: 2)) Point mutation (W46E, Q62W, G70E, A73P, K75C, S80P, T114H, N137V, D142R, S146E, R159Y, T161P, N176P, S187P, V211W, Y255D, A380P), a phytase mutant Phy7.2, which The amino acid sequence is SEQ ID NO: 3, and the coding nucleotide sequence is SEQ ID NO: 4.
  • the heat resistance of the phytase mutant Phy7.2 has been significantly improved. (This part has been in March 2016 Application No. 201610184337.1, filed on the 28th, is detailed in the domestic invention patent with the patent name "phytase mutant").
  • the invention discloses a phytase mutant, a preparation method and application thereof, and a DNA molecule, a vector, and a host cell encoding the phytase mutant.
  • Those skilled in the art can refer to the content of this article and appropriately improve process parameters for implementation.
  • the method and application of the present invention have been described through the preferred embodiments. It is obvious that relevant persons can modify or appropriately modify and combine the methods and applications described herein without departing from the content, spirit and scope of the present invention, to achieve and Apply the technology of the present invention.
  • the present invention uses conventional techniques and methods used in the fields of genetic engineering and molecular biology, such as MOLECULAR CLONING: ALABORATORY MANUAL, 3nd Ed. (Sambrook, 2001) and CURRENT PROTOCOLS IN MOLECULAR BIOLOGY (Ausubel, 2003) .
  • These general references provide definitions and methods known to those skilled in the art.
  • those skilled in the art may use other conventional methods, experimental protocols, and reagents in the art on the basis of the technical solutions described in the present invention, without being limited to the specific examples of the present invention.
  • the present invention may use the following experimental materials and reagents:
  • E. coli DH5 ⁇ , Pichia GS115, vectors pPIC9k, Amp, G418 were purchased from Invitrogen.
  • Enzymes and kits PCR enzymes and ligases were purchased from Takara company, restriction enzymes were purchased from Fermentas company, plasmid extraction kits and gel purification and recovery kits were purchased from Omega company, GeneMorphII random mutagenesis kits were purchased from Beijing Bo Max Biotech Co., Ltd.
  • E. coli medium (LB medium): 0.5% yeast extract, 1% peptone, 1% NaCL, pH 7.0);
  • LB-AMP medium LB medium plus 100 ⁇ g / mL ampicillin
  • Yeast medium 1% yeast extract, 2% peptone, 2% glucose;
  • Yeast screening medium 2% peptone, 2% agarose;
  • BMGY medium 2% peptone, 1% yeast extract, 100 mM potassium phosphate buffer (pH 6.0), 1.34% YNB, 4 ⁇ 10-5 biotin, 1% glycerol;
  • BMMY medium 2% peptone, 1% yeast extract, 100 mM potassium phosphate buffer (pH 6.0), 1.34% YNB, 4 ⁇ 10-5 biotin, 0.5% methanol.
  • the applicant analyzed the protein structure of the Phy7.2 gene SEQ ID NO: 4.
  • the protein has two domains: 134 amino acid residues at the N-terminus and C
  • the 152 amino acid residues at the end constitute Domain 1 together, and the remaining 124 amino acid residues constitute Domain 2.
  • the conserved sequence and active center are located in Domain 1 without further disrupting the secondary structure and active center of the protein. This gene is mutated.
  • Phy7.2-F1 GGC GAATTC CAGTCAGAACCAGAGTTGAAGTT (underlined by the restriction enzyme EcoRI recognition site), as shown in SEQ ID NO: 5;
  • Phy7.2-R1 ATA GCGGCCGC TTACAAGGAACAAGCAGGGAT (underlined is the restriction enzyme NotI recognition site), as shown in SEQ ID NO: 6;
  • PCR amplification was performed using GeneMorph II random mutation PCR kit (Stratagene) using the above primers, and the PCR product was recovered by gel digestion. EcoRI and NotI were digested with enzyme and The pET21a vector digested with the same enzyme was ligated, transformed into E. coli BL21 (DE3), spread on LB + Amp plates, and cultured upside down at 37 ° C. After the transformants appeared, pick each one to a 96-well plate with a toothpick. 150ul of LB + Amp medium containing 0.1mM IPTG was added to the wells, and cultured at 37 ° C and 220rpm for about 6 hours. The supernatant was discarded by centrifugation. The cells were resuspended with buffer solution and repeatedly freeze-thaw to break the wall to obtain E. coli cells containing phytase. Lysate.
  • the present invention provides mutants containing a single mutation site of M29A, D35Y, D117Y, K180N, A214H, Q253V, T260H or T327Y, respectively.
  • the invention also provides at least two, at least three, at least four, at least five, at least six, at least seven, and at least eight mutations comprising M29A, D35Y, D117Y, K180N, A214H, Q253V, T260H, or T327Y.
  • Phytase mutants at the site for example: M29A / K180N, D35Y / Q253V, D117Y / A214H, D117Y / T327Y or K180N / Q253V two-point mutants, M29A / D35Y / K180N, D35Y / K180N / T327Y, K180N / Q253V / T327Y, A214H / Q253V / T260H or K180N / A214H / Q253V three-point mutant, M29A / D117Y / T260H / T327Y, D35Y / K180N / Q253V / T327Y, D117Y / K180N / A214H / Q253V or K180N / A214H / Q253V / T260H Four-point mutant, M29A / K180N / A214H / Q253V / T260
  • the synthetic phytase mutant gene sequence was digested with EcoRI and NotI respectively, and then ligated to the pPIC-9K vector digested with the same enzyme at 16 ° C overnight, and transformed into E. coli DH5a, and spread on LB + Amp plates. Inverted culture at 37 ° C.
  • colony PCR reaction system: template-picked monoclonal, rTaqDNA polymerase 0.5ul, 10 ⁇ Buffer 2.0 ⁇ L, dNTPs (2.5mM) 2.0 ⁇ L, 5'AOX primer (10M ): 0.5 ⁇ L, 3 ′ AOX primer: 0.5 ⁇ L, ddH 2 O 14.5 ⁇ L, reaction procedure: predenaturation at 95 ° C. for 5 min, 30 cycles: 94 ° C. 30 sec, 55 ° C. 30 sec, 72 ° C. 2 min, 72 ° C. 10 min). The positive clones were verified, and the correct recombinant expression plasmid was obtained after verification by sequencing.
  • the Pichia pastoris GS115 strain was activated by YPD plate. After being cultured at 30 ° C for 48 hours, the activated GS115 monoclonal was inoculated in 6 mL of YPD liquid medium at 30 ° C and 220 rpm. After culturing for about 12 hours, the bacteria solution was transferred to a 30mLYPD liquid medium. Incubate in a conical flask at 30 ° C and 220rpm for about 5 hours. Detect the density of the bacteria by UV spectrophotometer. After the OD600 value is in the range of 1.1-1.3, centrifuge at 9000rpm for 2min at 4 ° C to collect 4mL bacteria to sterilized EP tubes.
  • the expression plasmids constructed in 2.1 were linearized with Sac I.
  • the linearized fragments were purified and recovered and transformed into Pichia pastoris GS115 by electroporation.
  • the recombinant strains of Pichia pastoris were screened on MD plates, and then inherited at different concentrations. Multiple copies of transformants were selected on YPD plates (0.5 mg / mL to 8 mg / mL) of mycin.
  • the obtained transformants were respectively transferred to BMGY medium and cultured with shaking at 30 ° C and 250rpm for 1d; then transferred into BMMY medium and cultured with shaking at 30 ° C and 250rpm; 0.5% methanol was added daily to induce expression for 4d; centrifugation at 9000rpm After 10 minutes of bacterial removal, a fermentation supernatant containing phytase Phy7.2 and its mutant was obtained.
  • X unit of enzyme activity, U / g (mL);
  • the above method was used to determine the phytase enzyme activity of the constructed Pichia recombinant strain fermentation supernatant.
  • Fermentation of Pichia recombinant strains was performed on 10 liter fermentors.
  • the medium formula used for fermentation was: calcium sulfate 1.1g / L, potassium dihydrogen phosphate 5.5g / L, ammonium dihydrogen phosphate 55g / L, and magnesium sulfate. 16.4g / L, potassium sulfate 20.3g / L, potassium hydroxide 1.65g / L, defoamer 0.05%.
  • Fermentation production process pH 5.0, temperature 30 ° C, stirring rate 300 rpm, ventilation volume 1.0-1.5 (v / v), dissolved oxygen control above 20%.
  • the entire fermentation process is divided into three stages: the first stage is the bacterial cell culture stage, the seeds are inserted at a rate of 7%, and the culture is incubated at 30 ° C for 24-26 hours, which is marked by the completion of glucose; the second stage is the starvation stage, when the glucose is supplemented After finishing, do not add any carbon source, when the dissolved oxygen rises above 80%, it indicates the end of this phase, which lasts for about 30-60min; the third phase is the induction expression phase, which is induced by the addition of methanol, and the dissolved oxygen is kept above 20% ,
  • the culture time is between 150-180h; after the fermentation is completed, the fermentation broth is processed by a plate and frame filter to obtain a crude enzyme solution.
  • Example 3 The method described in Example 3 was used to detect the enzyme activity of the crude enzyme solution, and the results showed that the final fermentation enzyme activity of the Pichia recombinant strain that recombinantly expressed the phytase Phy7.2 and its mutant was 12055-13000 U / mL.
  • the treatment is as follows: treatment at 85 ° C. for 5 minutes, treatment at 90 ° C. for 3 minutes, sampling at the end and cooling to room temperature; the phytase enzyme activity of the samples after heat treatment is measured respectively, and 100% of the enzyme activity of the untreated sample is used to calculate the enzyme activity residual rate.
  • Enzyme residual rate (%) Enzyme activity of untreated sample / Enzyme activity of sample after heat treatment ⁇ 100%
  • the present invention provides a phytase mutant comprising a combination of any two or more mutation sites in M29A, D35Y, D117Y, K180N, A214H, Q253V, T260H or T327Y, for example: M29A / K180N, D35Y / Q253V , D117Y / A214H, D117Y / T327Y or K180N / Q253V two-point mutants, M29A / D35Y / K180N, D35Y / K180N / T327Y, K180N / Q253V / T327Y, A214H / Q253V / T260H or K180N / A214H / Q253V three-point mutants , M29A / D117Y / T260H / T327Y, D35Y / K180N / Q253V / T327Y, D117Y / K180N / A214H, M
  • the present invention provides a mutant comprising at least one mutation site in M29A, D35Y, D117Y, K180N, A214H, Q253V, T260H or T327Y based on the phytase Phy7.2.
  • the heat resistance of the mutant is significantly improved, thereby facilitating its wide application in feed.

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Abstract

涉及生物技术领域，特别涉及一种植酸酶突变体、其制备方法及应用、编码该植酸酶突变体的DNA分子、载体、宿主细胞。提供的突变体的耐热性得到显著提高，从而有利于植酸酶在饲料中的广泛应用。

Description

植酸酶突变体
本申请要求于2018年09月28日提交中国专利局、申请号为201811136563.8、发明名称为“植酸酶突变体”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及生物技术领域，特别涉及一种植酸酶突变体、其制备方法及应用、编码该植酸酶突变体的DNA分子、载体、宿主细胞。
背景技术
植酸酶是一种能水解植酸的磷酸酶类。它能将植酸磷(六磷酸肌醇)降解为肌醇和无机磷酸。此酶分为两类：3-植酸酶(EC.3.1.3.8)和6-植酸酶(EC.3.1.2.6)。植酸酶广泛存在于植物、动物和微生物中，如玉米、小麦等高等植物，枯草芽孢杆菌、假单孢杆菌、乳酸杆菌、大肠杆菌等原核微生物及酵母、根霉、曲霉等真核微生物中。
在谷物、豆类和油料等作物籽实中，磷的基本贮存形式是植酸磷，其含量高达1％～3％，它占植物中总磷的60％～80％。但是以植酸磷形式存在的磷却因单胃动物体内缺乏能分解植酸的酶而难以被利用，其利用率仅在0％～40％，从而造成了许多问题：首先是造成磷源浪费，一方面饲料中的磷源不能得到有效利用，另一方面为了满足动物对磷的需求，又必须在饲料中添加无机磷，提高了饲料成本；其次是形成高磷粪便污染环境。饲料中85％左右的植酸磷会被动物直接排出体外，粪便中大量的植酸磷使水和土壤受到严重污染。另外，植酸磷还是一种抗营养因子，它在动物胃肠道的消化吸收过程中会与多种金属离子如Zn 2+、Ca 2+、Cu 2+、Fe 2+等以及蛋白质螯合成相应的不溶性复合物，降低了动物对这些营养物质的有效利用。
植酸酶可作为一种单胃动物的饲料添加剂，它的饲喂效果已在世界范围内得到了确证。它可使植物性饲料中磷的利用率提60％，粪便中磷排泄量减少40％，同时还可降低植酸的抗营养作用。因此在饲料中添加植 酸酶对提高畜禽业生产效益及降低植酸磷对环境的污染有重要意义。
现工业化生产的植酸酶主要有来源于黑曲霉的真菌植酸酶和来源于大肠杆菌的细菌植酸酶两种。其中来源于大肠杆菌的植酸酶APPA具有高比活性及良好的消化道稳定性等特点。目前主要通过在粉末饲料直接添加或颗粒饲料后喷涂的方法应用在饲料行业。
因为目前在颗粒饲料生产过程中有一个短暂的80-90℃的高温阶段。细菌植酸酶APPA热稳定性较差，其水溶液在70℃下保温5分钟剩余酶活性低于30％，直接添加到动物饲料中进行制粒后存留酶活一般低于20％，使APPA植酸酶在颗粒饲料的应用受到限制。采用饲料制粒后植酸酶液体喷涂到饲料上的方法不仅增加设备投入，而且对酶制剂的稳定性、饲料中分布均一性都无法很好的保证。因此，提高热稳定性对目前饲料用植酸酶具有重要的现实意义。
发明内容
有鉴于此，本发明提供一种植酸酶突变体，获得突变体蛋白，提高其耐热性，从而有利于植酸酶在饲料领域的广泛应用。
为了实现上述发明目的，本发明提供以下技术方案：
本发明提供了一种植酸酶突变体，其具有(I)、(II)或(III)所示的氨基酸序列中任意一个：
(I)与植酸酶的氨基酸序列SEQ ID NO：1具有至少90％同源性的序列；
(II)具有所述植酸酶的至少一个免疫表位，且所述植酸酶的氨基酸序列经修饰、取代、缺失或添加一个或几个氨基酸获得的氨基酸序列；
(III)由如SEQ ID NO：2所示的核苷酸序列或其互补序列或因遗传密码的简并性而与如SEQ ID NO：2所示的核苷酸序列或其互补序列的核苷酸序列不同的序列编码的氨基酸序列；
在本发明的一些实施例中，所述取代为取代1个、2个、3个、4个、5个、6个、7个、8个、9个、10个、11个、12个、13个、14个、15个、16个、17个、18个、19个、20个、21个、22个、23个、24个或 25个氨基酸。
在本发明的一些实施例中，植酸酶突变体的氨基酸序列与植酸酶的氨基酸序列具有至少95％同源性的序列。
在本发明的另一些实施例中，植酸酶突变体的氨基酸序列与植酸酶的氨基酸序列具有至少96％同源性的序列。
在本发明的另一些实施例中，植酸酶突变体的氨基酸序列与植酸酶的氨基酸序列具有至少97％同源性的序列。
在本发明的另一些实施例中，植酸酶突变体的氨基酸序列与植酸酶的氨基酸序列具有至少98％同源性的序列。
在本发明的另一些实施例中，植酸酶突变体的氨基酸序列与植酸酶的氨基酸序列具有至少99％同源性的序列。
在本发明的一些实施例中，所述修饰包括酰胺化、磷酸化、甲基化、乙酰化、泛素化、糖基化或羰基化。
在本发明的一些实施例中，所述取代为取代18个、19个、20个、21个、22个、23个、24个或25个氨基酸。
在本发明的另一些实施例中，所述取代为第29位、第35位、第46位、第62位、第70位、第73位、第75位、第80位、第114位、第117位、第137位、第142位、第146位、第159位、第161位、第176位、第180位、第187位、第211位、第214位、第253位、第255位、第260位、第327位或第380位中的一个或多个氨基酸被取代。
在本发明的另一些实施例中，所述取代为第46位、第62位、第70位、第73位、第75位、第80位、第114位、第137位、第142位、第146位、第159位、第161位、第176位、第187位、第211位、第255位和第380位的氨基酸被取代。
在本发明的一些实施例中，所述植酸酶具有如SEQ ID NO：1所示的氨基酸序列，编码所述植酸酶的核苷酸序列之一如SEQ ID NO：2所示。
在本发明的另一些实施例中，所述取代为氨基酸序列为SEQ ID NO：1的植酸酶的第46位氨基酸由Trp变为Glu，第62位氨基酸由Gln变为Trp，第70位氨基酸由Gly变为Glu，第73位氨基酸由Ala变为Pro，第75位 氨基酸由Lys变为Cys，第80位氨基酸由Ser变为Pro，第114位氨基酸由Thr变为His，第137位氨基酸由Asn变为Val，第142位氨基酸由Asp变为Arg，第146位氨基酸由Ser变为Glu，第159位氨基酸由Arg变为Tyr，第161位氨基酸由Thr变为Pro，第176位氨基酸由Asn变为Pro，第187位氨基酸由Ser变为Pro，第211位氨基酸由Val变为Trp，第255位氨基酸由Tyr变为Asp，和第380位氨基酸由Ala变为Pro。
上述植酸酶突变体的氨基酸序列如SEQ ID NO：3所示，编码的核甘酸序列之一如SEQ ID NO：4所示。
本发明还包括携带有编码序列为SEQ ID NO：4的植酸酶突变体基因的质粒。
在本发明的另一些实施例中，所述取代还包括第29位、第35位、第117位、第180位、第214位、第253位、第260位或第327位的一个或多个氨基酸被取代。
在本发明的一些实施例中，所述取代选自下组中至少一个氨基酸的取代：M29A，D35Y，D117Y，K180N，A214H，Q253V，T260H或T327Y。
在本发明的一些实施例中，所述突变体包含的取代或取代的组合选自下述取代和取代的组合：
M29A；
M29A/D35Y；
M29A/D117Y；
M29A/K180N；
M29A/A214H；
M29A/Q253V；
M29A/T260H；
M29A/T327Y；
M29A/D35Y/K180N；
M29A/D35Y/Q253V；
M29A/D35Y/T260H；
M29A/K180N/Q253V/T327Y；
M29A/D117Y/T260H/T327Y；
M29A/K180N/A214H/Q253V/T327Y；
M29A/D35Y/K180N/A214H/Q253V/T327Y；
D35Y；
D35Y/D117Y；
D35Y/K180N；
D35Y/A214H；
D35Y/Q253V；
D35Y/T260H；
D35Y/T327Y；
D35Y/D117Y/K180N；
D35Y/K180N/Q253V；
D35Y/K180N/T260H；
D35Y/K180N/T 327Y；
D35Y/Q253V/T327Y；
D35Y/K180N/Q253V/T327Y；
D35Y/D117Y/A214H/T327Y；
D35Y/K180N/A214H/Q253V/T327Y；
D35Y/K180N/Q253V/T260H/T327Y；
D35Y/D117Y/K180N/A214H/Q253V/T260H；
D117Y；
D117Y/K180N；
D117Y/A214H；
D117Y/Q253V；
D117Y/T327Y；
D117Y/K180N/A214H；
D117Y/A214H/Q253V；
D117Y/T260H/T327Y；
D117Y/K180N/A214H/Q253V；
D117Y/K180N/A214H/Q253V/T260H；
K180N；
K180N/A214H；
K180N/Q253V；
K180N/T260H；
K180N/T327Y；
K180N/A214H/Q253V；
K180N/A214H/Q253V/T260H；
K180N/A214H/Q253V/T327Y；
A214H；
A214H/Q253V；
A214H/T260H；
A214H/T327Y；
A214H/Q253V/T260H；
A214H/Q253V/T260H/T327Y；
Q253V；
Q253V/T260H；
Q253V/T327Y；
Q253V/T260H/T327Y；
K180N/Q253V/T327Y；
T260H；
T260H/T327Y；
T327Y；
M29A/D35Y/K180N/A214H/Q253V/T260H；
D35Y/D117Y/K180N/A214H/Q253V/T327Y；
M29A/D35Y/D117Y/K180N/A214H/Q253V/T260H；
D35Y/D117Y/K180N/A214H/Q253V/T260H/T327Y；
M29A/D35Y/D117Y/K180N/A214H/Q253V/T260H/T327Y。
本发明还涉及编码上述植酸酶突变体的DNA分子。
本发明还涉及包含上述DNA分子的重组表达载体。
本发明还涉及一种宿主细胞，包含上述重组表达载体。
将上述的质粒转入宿主细胞中，重组表达的植酸酶突变体的耐热性得到显著提升。本发明还提供了上述植酸酶突变体的制备方法，包括：
步骤1：获取编码具有(I)、(II)或(III)所示的氨基酸序列中任意一个的DNA分子：
(I)与植酸酶的氨基酸序列具有至少90％同源性的序列；
(II)具有植酸酶的至少一个免疫表位，且所述植酸酶的氨基酸序列经修饰、取代、缺失或添加一个或几个氨基酸获得的氨基酸序列；
(III)由如SEQ ID NO：2所示的核苷酸序列或其互补序列或因遗传密码的简并性而与如SEQ ID NO：2所示的核苷酸序列或其互补序列的核苷酸序列不同的序列编码的氨基酸序列；
所述取代为取代1个、2个、3个、4个、5个、6个、7个、8个、9个、10个、11个、12个、13个、14个、15个、16个、17个、18个、19个、20个、21个、22个、23个、24个或25个氨基酸；
步骤2：将步骤1获得的所述DNA分子与表达载体融合，构建重组表达载体，转化宿主细胞；
步骤3：诱导含重组表达载体的宿主细胞表达融合蛋白，分离纯化表达的融合蛋白。
在本发明的一些实施例中，制备方法中所述修饰包括酰胺化、磷酸化、甲基化、乙酰化、泛素化、糖基化或羰基化。
在本发明的一些实施例中，制备方法中所述取代为第29位、第35位、第46位、第62位、第70位、第73位、第75位、第80位、第114位、第117位、第137位、第142位、第146位、第159位、第161位、第176位、第180位、第187位、第211位、第214位、第253位、第255位、第260位、第327位或第380位中的一个或多个氨基酸被取代。
在本发明的另一些实施例中，所述取代为第46位、第62位、第70位、第73位、第75位、第80位、第114位、第137位、第142位、第146位、第159位、第161位、第176位、第187位、第211位、第255 位和第380位的氨基酸被取代。
在本发明的另一些实施例中，制备方法中所述取代还包括第29位、第35位、第117位、第180位、第214位、第253位、第260位或第327位的一个或多个氨基酸被取代。
在本发明的另一些实施例中，所述取代选自下组中至少一个氨基酸的取代：M29A，D35Y，D117Y，K180N，A214H，Q253V，T260H或T327Y。
本发明还提供了上述植酸酶突变体在饲料中的应用。
本发明以植酸酶Phy7.2为基础，提供的包含M29A、D35Y、D117Y、K180N、A214H、Q253V、T260H或T327Y中至少一个突变位点的突变体，其耐热性得到显著提升。在85℃条件下处理5min后，所述突变体的酶活残留率为71％-95％，比植酸酶Phy7.2提高了11％-48％；90℃处理3min后，所述突变体的酶活残留率为42％-57％，比植酸酶Phy7.2提高了8％-41％，取得了意料不到的技术效果。本发明提供的植酸酶突变体可广泛应用于饲料领域。
具体实施方式
本发明公开了一种植酸酶突变体，本领域技术人员可以借鉴本文内容，适当改进工艺参数实现。特别需要指出的是，所有类似的替换和改动对本领域技术人员来说是显而易见的，它们都被视为包括在本发明。本发明的方法及应用已经通过较佳实施例进行了描述，相关人员明显能在不脱离本发明内容、精神和范围内对本文所述的方法和应用进行改动或适当变更与组合，来实现和应用本发明技术。
本发明提供的植酸酶突变体中所用原料及试剂均可由市场购得。
为了提高植酸酶的耐热性，申请人在野生型植酸酶APPA((氨基酸序列为SEQ ID NO：1，其编码核苷酸序列为SEQ ID NO：2)基础上进行了17个位点突变(W46E，Q62W，G70E，A73P，K75C，S80P，T114H，N137V，D142R，S146E，R159Y，T161P，N176P，S187P，V211W，Y255D，A380P)，获得了植酸酶突变体Phy7.2，其氨基酸序列为SEQ ID NO：3，其编码核苷酸序列为SEQ ID NO：4。所述植酸酶突变体Phy7.2的耐热性 得到显著提升。(此部分内容已经在2016年3月28日申请的申请号为201610184337.1、专利名称为“植酸酶突变体”的国内发明专利中详细阐述)。
本发明公开了一种植酸酶突变体、其制备方法及应用、编码该植酸酶突变体的DNA分子、载体、宿主细胞，本领域技术人员可以借鉴本文内容，适当改进工艺参数实现。本发明的方法及应用已经通过较佳实施例进行了描述，相关人员明显能在不脱离本发明内容、精神和范围内对本文所述的方法和应用进行改动或适当变更与组合，来实现和应用本发明技术。
本发明用到了遗传工程和分子生物学领域使用的常规技术和方法，例如MOLECULAR CLONING：A LABORATORY MANUAL，3nd Ed.(Sambrook，2001)和CURRENT PROTOCOLS IN MOLECULAR BIOLOGY(Ausubel，2003)中所记载的方法。这些一般性参考文献提供了本领域技术人员已知的定义和方法。但是，本领域的技术人员可以在本发明所记载的技术方案的基础上，采用本领域其它常规的方法、实验方案和试剂，而不限于本发明具体实施例的限定。例如，本发明可选用如下实验材料和试剂：
菌株与载体：大肠杆菌DH5α、毕赤酵母GS115、载体pPIC9k、Amp、G418购自Invitrogen公司。
酶与试剂盒：PCR酶及连接酶购买自Takara公司，限制性内切酶购自Fermentas公司，质粒提取试剂盒及胶纯化回收试剂盒购自Omega公司，GeneMorphII随机诱变试剂盒购自北京博迈斯生物科技有限公司。
培养基配方：
大肠杆菌培养基(LB培养基)：0.5％酵母提取物，1％蛋白胨，1％NaCL，pH7.0)；
LB-AMP培养基：LB培养基加100μg/mL氨苄青霉素；
酵母培养基(YPD培养基)：1％酵母提取物、2％蛋白胨2％葡萄糖；
酵母筛选培养基(MD培养基)：2％蛋白胨、2％琼脂糖；
BMGY培养基：2％蛋白胨，1％酵母提取物，100mM磷酸钾缓冲液(pH6.0)，1.34％YNB，4×10-5生物素，1％甘油；
BMMY培养基：2％蛋白胨，1％酵母提取物，100mM磷酸钾缓冲液(pH6.0)，1.34％YNB，4×10-5生物素，0.5％甲醇。
下面结合实施例，进一步阐述本发明：
实施例1 耐热突变体的筛选
为了进一步提高植酸酶突变体Phy7.2的耐热性，申请人对Phy7.2基因SEQ ID NO：4进行蛋白结构分析，该蛋白有两个结构域：N端的134个氨基酸残基与C端的152个氨基酸残基共同组成结构域1，剩余中间124氨基酸残基组成结构域2，保守序列和活性中心均位于结构域1中，在不破坏蛋白二级结构与活性中心的前提下，进一步对该基因进行突变。
1.1设计PCR引物Phy7.2-F1、Phy7.2-R1：
Phy7.2-F1：GGC GAATTC CAGTCAGAACCAGAGTTGAAGTT(下划线为限制性内切酶EcoRI识别位点)，如SEQ ID NO：5所示；
Phy7.2-R1：ATA GCGGCCGC TTACAAGGAACAAGCAGGGAT(下划线为限制性内切酶NotI识别位点)，如SEQ ID NO：6所示；
以Phy7.2-F1基因(SEQ ID NO：4)为模板，利用上述引物用GeneMorph II随机突变PCR试剂盒(Stratagene)进行PCR扩增，胶回收PCR产物，EcoRI、NotI进行酶切处理后与经同样酶切后的pET21a载体连接，转化至大肠杆菌BL21(DE3)中，涂布于LB+Amp平板，37℃倒置培养，待转化子出现后，用牙签逐个挑至96孔板，每个孔中加入150ul含有0.1mM IPTG的LB+Amp培养基，37℃ 220rpm培养6h左右，离心弃上清，菌体用缓冲液重悬，反复冻融破壁，获得含有植酸酶的大肠杆菌细胞裂解液。
分别取出40ul裂解液至两块新的96孔板，将其中一块96孔板于80℃处理10min；然后向两块96孔板中各加入80ul底物，于37℃反应30min后加入80ul终止液(钒酸铵∶钼酸铵∶硝酸＝1∶1∶2)，测定生成的无机磷含量。不同的突变子高温处理后保持的活性不同。
实验结果表明，有些突变对Phy7.2蛋白耐热性没有影响，有些突变甚至使其耐热性或酶活变得更差了，另外还有些突变虽然能提高Phy7.2蛋白对温度的耐受性，但突变后其酶学性质发生了显著的变化，这些均不符合要求。最终，申请人得到既能显著提高Phy7.2蛋白耐热性，又不会影 响其酶活及原有酶学性质的突变位点：M29A，D35Y，D117Y，K180N，A214H，Q253V，T260H，T327Y。
在上述植酸酶Phy7.2的基础上，本发明提供了分别含M29A、D35Y、D117Y、K180N、A214H、Q253V、T260H或T327Y单个突变位点的突变体。
本发明还提供了包含M29A、D35Y、D117Y、K180N、A214H、Q253V、T260H或T327Y中至少2个，至少3个，至少4个，至少5个，至少6个，至少7个，至少8个突变位点的植酸酶突变体，例如：M29A/K180N、D35Y/Q253V、D117Y/A214H、D117Y/T327Y或K180N/Q253V两点突变体，M29A/D35Y/K180N、D35Y/K180N/T327Y、K180N/Q253V/T327Y、A214H/Q253V/T260H或K180N/A214H/Q253V三点突变体，M29A/D117Y/T260H/T327Y、D35Y/K180N/Q253V/T327Y、D117Y/K180N/A214H/Q253V或K180N/A214H/Q253V/T260H四点突变体，M29A/K180N/A214H/Q253V/T327Y或D35Y/K180N/A214H/Q253V/T327Y五点突变体，D35Y/D117Y/K180N/A214H/Q253V/T260H或D35Y/D117Y/K180N/A214H/Q253V/T327Y六点突变体，M29A/D35Y/D117Y/K180N/A214H/Q253V/T260H或D35Y/D117Y/K180N/A214H/Q253V/T260H/T327Y七点突变体，以及M29A/D35Y/D117Y/K180N/A214H/Q253V/T260H/T327Y八点突变体；等等。
实施例2 植酸酶突变体在毕赤酵母中的表达
依照毕赤酵母的密码偏爱性分别对植酸酶Phy7.2的基因序列SEQ ID NO：4，以及突变体的基因序列进行优化合成，并且在合成序列5’和3’两端分别加上EcoRI和NotI两个酶切位点。
2.1表达载体的构建
将合成的植酸酶突变体基因序列分别进行EcoRI和NotI双酶切，然后与经同样酶切后的pPIC-9K载体16℃过夜连接，并转化大肠杆菌DH5a，涂布于LB+Amp平板，37℃倒置培养，待转化子出现后，菌落PCR(反 应体系：模板挑取的单克隆，rTaqDNA聚合酶0.5ul，10×Buffer 2.0μL，dNTPs(2.5mM)2.0μL，5’AOX引物(10M)：0.5μL，3’AOX引物：0.5μL，ddH 2O 14.5μL，反应程序：95℃预变性5min，30cycles：94℃ 30sec，55℃ 30sec，72℃ 2min，72℃ 10min)。验证阳性克隆子，经测序验证后获得了正确的重组表达质粒。
2.2毕赤酵母工程菌株的构建
2.2.1酵母感受态制备
将毕赤酵母GS115菌株进行YPD平板活化，30℃培养48h后接种活化的GS115单克隆于6mL YPD液体培养基中，30℃、220rpm，培养约12h后转接菌液于装有30mLYPD液体培养基的三角瓶中，30℃、220rpm培养约5h，经紫外分光光度计检测其菌体密度，待其OD600值在1.1-1.3范围后，4℃ 9000rpm离心2min分别收集4mL菌体至灭菌EP管中，轻轻弃上清，用灭菌的滤纸吸干残留的上清后用预冷的1mL灭菌水重悬菌体，4℃、9000rpm离心2min，轻轻弃上清，重复用1mL灭菌水洗一遍后，4℃、9000rpm离心2min，轻轻弃上清，预冷的1mL山梨醇(1mol/L)重悬菌体；4℃、9000rpm离心2min，轻轻弃上清，预冷的100-150μl山梨醇(1mol/L)轻柔重悬菌体。
2.2.2转化和筛选
分别将2.1构建得到的表达质粒用Sac I进行线性化，线性化片段纯化回收后通过电穿孔法分别转化毕赤酵母GS115，在MD平板上筛选得到毕赤酵母重组菌株，然后在含不同浓度遗传霉素的YPD平板(0.5mg/mL-8mg/mL)上筛选多拷贝的转化子。
将获得的转化子分别转接于BMGY培养基中，30℃、250rpm振荡培养1d；再转入BMMY培养基中，30℃、250rpm振荡培养；每天添加0.5％的甲醇，诱导表达4d；9000rpm离心10min去除菌体，即得到分别含植酸酶Phy7.2及其突变体的发酵上清液。
实施例3 植酸酶酶活检测
3.1酶活定义
在温度为37℃、pH为5.0的条件下，每分钟从浓度为5.0mmol/L植 酸钠中释放1μmol无机磷，即为一个植酸酶活性单位，以U表示。
3.2植酸酶酶活测定方法
取甲、乙两支25mL比色管，各加入1.8mL乙酸缓冲液(pH 5.0)、0.2mL样品反应液，混匀，37℃预热5min。在甲管中加入4mL底物溶液，乙管中加入4mL终止液，混匀，37℃反应30min，反应结束后甲管中加入4mL终止液，乙管中加入4mL底物溶液，混匀。静置10min，分别在415nm波长处测定吸光值。每种样品作3个平行，取吸光值的平均值，通过标准曲线用回归直线方程计算植酸酶活性。
酶活X＝F×C/(m×30)
其中：X——酶活力单位，U/g(mL)；
F——试样溶液反应前的总稀释倍数；
C——根据实际样液的吸光值由直线回归方程计算出的酶活性，U；
m——试样质量或体积，g/mL；
30——反应时间。
采用上述方法分别对构建得到的毕赤酵母重组菌株发酵上清液进行植酸酶酶活测定。
结果显示，上述构建得到的重组表达植酸酶Phy7.2及其突变体的毕赤酵母重组菌株发酵上清液的酶活为253-300U/mL。
实施例4 发酵验证
在10升发酵罐上分别进行毕赤酵母重组菌株的发酵，发酵使用的培养基配方为：硫酸钙1.1g/L、磷酸二氢钾5.5g/L、磷酸二氢铵55g/L、硫酸镁16.4g/L、硫酸钾20.3g/L、氢氧化钾1.65g/L、消泡剂0.05％。
发酵生产工艺：pH5.0、温度30℃、搅拌速率300rpm、通风量1.0-1.5(v/v)、溶氧控制在20％以上。
整个发酵过程分为三个阶段：第一阶段为菌体培养阶段，按7％比例接入种子，30℃培养24-26h，以补完葡萄糖为标志；第二阶段为饥饿阶段，当葡萄糖补完之后，不流加任何碳源，当溶氧上升至80％以上表明该阶段结束，为期约30-60min；第三阶段为诱导表达阶段，流加甲醇诱导，并且保持溶氧在20％以上，培养时间在150-180h之间；发酵结束后， 发酵液通过板框过滤机处理后获得粗酶液。
采用实施例3所述方法对上述粗酶液进行酶活检测，结果显示：重组表达植酸酶Phy7.2及其突变体的毕赤酵母重组菌株最终的发酵酶活为12055-13000U/mL。
实施例5 植酸酶突变体热稳定性分析
用预热10min、pH5.0的0.25M乙酸钠缓冲液将上述获得的表达植酸酶Phy7.2及其突变体的重组菌株发酵上清液各稀释10倍；然后将稀释后的样品分别进行如下处理：85℃处理5min，90℃处理3min，结束时取样并冷却至室温；分别测定热处理后样品的植酸酶酶活，以未处理样品的酶活计100％，计算酶活残留率。
酶活残留率(％)＝未处理样品的酶活/热处理后样品的酶活×100％
结果显示，本发明提供的分别包含M29A、D35Y、D117Y、K180N、A214H、Q253V、T260H或T327Y单个突变位点的植酸酶突变体，在85℃条件下处理5min后，酶活残留率为71％-85％，比植酸酶Phy7.2提高了11％-33％；90℃处理3min后，酶活残留率为42％-49％，比植酸酶Phy7.2提高了8％-26％。从而说明，本发明在植酸酶Phy7.2基础上提供的单点突变体耐热水平得到显著提高。
此外，本发明提供的包含M29A、D35Y、D117Y、K180N、A214H、Q253V、T260H或T327Y中任意2个或2个以上突变位点组合的植酸酶突变体，例如：M29A/K180N、D35Y/Q253V、D117Y/A214H、D117Y/T327Y或K180N/Q253V两点突变体，M29A/D35Y/K180N、D35Y/K180N/T327Y、K180N/Q253V/T327Y、A214H/Q253V/T260H或K180N/A214H/Q253V三点突变体，M29A/D117Y/T260H/T327Y、D35Y/K180N/Q253V/T327Y、D117Y/K180N/A214H/Q253V或K180N/A214H/Q253V/T260H四点突变体，M29A/K180N/A214H/Q253V/T327Y或D35Y/K180N/A214H/Q253V/T327Y五点突变体，D35Y/D117Y/K180N/A214H/Q253V/T260H或D35Y/D117Y/K180N/A214H/Q253V/T327Y六点突变体，M29A/D35Y/D117Y/K180N/A214H/Q253V/T260H或 D35Y/D117Y/K180N/A214H/Q253V/T260H/T327Y七点突变体，以及M29A/D35Y/D117Y/K180N/A214H/Q253V/T260H/T327Y八点突变体；等等，在85℃条件下处理5min后，所述突变体的酶活残留率为71％-95％，比植酸酶Phy7.2提高了11％-48％；90℃处理3min后，所述突变体的酶活残留率为42％-57％，比植酸酶Phy7.2提高了8％-41％，取得了意料不到的技术效果。
综上，本发明以植酸酶Phy7.2为基础，提供了包含M29A、D35Y、D117Y、K180N、A214H、Q253V、T260H或T327Y中至少一个突变位点的突变体。所述突变体的耐热性得到显著提升，从而有利于其在饲料中的广泛应用。

Claims (9)

  1. 一种植酸酶突变体，其特征在于，所述突变体包含与SEQ ID NO：1具有至少90％同源性的氨基酸序列，且与SEQ ID NO：1相比包含至少一个氨基酸的取代，其中所述氨基酸取代在选自下组的位置编号处：第29位，第35位，第46位，第62位，第70位，第73位，第75位，第80位，第114位，第117位，第137位，第142位，第146位，第159位，第161位，第176位，第180位，第187位，第211位，第214位，第253位，第255位，第260位，第327位或第380位。
  2. 根据权利要求1所述的植酸酶突变体，其特征在于，所述突变体包含的取代选自下组：M29A，D35Y，W46E，Q62W，G70E，A73P，K75C，S80P，T114H，D117Y，N137V，D142R，S146E，R159Y，T161P，N176P，K180N，S187P，V211W，A214H，Q253V，Y255D，T260H，T327Y或A380P。
  3. 根据权利要求1所述的植酸酶突变体，其特征在于，所述突变体包含氨基酸取代W46E/Q62W/G70E/A73P/K75C/S80P/T114H/N137V/D142R/S146E/R159Y/T161P/N176P/S187P/V211W/Y255D/A380P。
  4. 根据权利要求3所述的植酸酶突变体，其特征在于，所述突变体还包含至少一个在选自下组的位置编号处的氨基酸取代：第29位，第35位，第117位，第180位，第214位，第253位，第260位或第327位。
  5. 根据权利要求4所述的植酸酶突变体，其特征在于，所述突变体包含的取代选自下组：M29A，D35Y，D117Y，K180N，A214H，Q253V，T260H或T327Y。
  6. 根据权利要求4或5所述的植酸酶突变体，其特征在于，所述突变体包含的取代选自下组：
    M29A；
    M29A/D35Y；
    M29A/D117Y；
    M29A/K180N；
    M29A/A214H；
    M29A/Q253V；
    M29A/T260H；
    M29A/T327Y；
    M29A/D35Y/K180N；
    M29A/D35Y/Q253V；
    M29A/D35Y/T260H；
    M29A/K180N/Q253V/T327Y；
    M29A/D117Y/T260H/T327Y；
    M29A/K180N/A214H/Q253V/T327Y；
    M29A/D35Y/K180N/A214H/Q253V/T327Y；
    D35Y；
    D35Y/D117Y；
    D35Y/K180N；
    D35Y/A214H；
    D35Y/Q253V；
    D35Y/T260H；
    D35Y/T327Y；
    D35Y/D117Y/K180N；
    D35Y/K180N/Q253V；
    D35Y/K180N/T260H；
    D35Y/K180N/T327Y；
    D35Y/Q253V/T327Y；
    D35Y/K180N/Q253V/T327Y；
    D35Y/D117Y/A214H/T327Y；
    D35Y/K180N/A214H/Q253V/T327Y；
    D35Y/K180N/Q253V/T260H/T327Y；
    D35Y/D117Y/K180N/A214H/Q253V/T260H；
    D117Y；
    D117Y/K180N；
    D117Y/A214H；
    D117Y/Q253V；
    D117Y/T327Y；
    D117Y/K180N/A214H；
    D117Y/A214H/Q253V；
    D117Y/T260H/T327Y；
    D117Y/K180N/A214H/Q253V；
    D117Y/K180N/A214H/Q253V/T260H；
    K180N；
    K180N/A214H；
    K180N/Q253V；
    K180N/T260H；
    K180N/T327Y；
    K180N/A214H/Q253V；
    K180N/A214H/Q253V/T260H；
    K180N/A214H/Q253V/T327Y；
    A214H；
    A214H/Q253V；
    A214H/T260H；
    A214H/T327Y；
    A214H/Q253V/T260H；
    A214H/Q253V/T260H/T327Y；
    Q253V；
    Q253V/T260H；
    Q253V/T327Y；
    Q253V/T260H/T327Y；
    K180N/Q253V/T327Y；
    T260H；
    T260H/T327Y；
    T327Y；
    M29A/D35Y/K180N/A214H/Q253V/T260H；
    D35Y/D117Y/K180N/A214H/Q253V/T327Y；
    M29A/D35Y/D117Y/K180N/A214H/Q253V/T260H；
    D35Y/D117Y/K180N/A214H/Q253V/T260H/T327Y；
    M29A/D35Y/D117Y/K180N/A214H/Q253V/T260H/T327Y。
  7. 编码如权利要求1-6任一所述的植酸酶突变体的DNA分子。
  8. 具有如权利要求7所述DNA分子的载体。
  9. 一种宿主细胞，其特征在于，包含如权利要求8所述的载体。
PCT/CN2019/104088 2018-09-28 2019-09-03 植酸酶突变体 WO2020063268A1 (zh)

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