KR20020000935A - Expression vector(pGP1) for a novel phytase and Pichia pastoris-pGP1 transformant producing recombinant phytase - Google Patents

Abstract

PURPOSE: An expression vector for a phytase gene and a Pichia pastoris(pho1) transformant capable of producing a recombinant phytase using the same vector are provided, thereby mass-producing a stable recombinant phytase. CONSTITUTION: The recombinant plasmid vector pGP1 contains a phytase gene isolated from Pichia anomala and a portion of the phytase gene. A Pichia (pastoris(pho1))-pGP1 transformant (KCTC 18024P) is produced by preparing Pichia pastoris(pho1) incapable of expressing phosphatase; amplifying a phytase gene from the genomic DNA of Pichia anomala using a primer; preparing a recombinant plasmid pGP1; transforming Pichia pastoris(pho1) with the recombinant plasmid vector pGP1; and selecting transformants by cultivating Pichia pastoris(pho1)-pGP1 in a medium containing zeocin.

Description

A novel phytase gene expression vector and a transformed Pchia pastoris yeast strain producing a recombinant phytez using the same {Expression vector (pGP1) for a novel phytase and Pichia pastoris-pGP1 transformant producing recombinant phytase}

The present invention relates to a phytase gene expression vector of Pichia anomala and a yeast strain producing a novel recombinant phytez using the same. More specifically, the present invention introduces a transformed vector incorporating a Pythean gene derived from Peachia anomala into a Peachia pastoris yeast strain, transforms it, and fermentes and cultures it to produce a recombinant Pitez. It relates to a yeast strain.

Recently, due to the serious problems of environmental and water pollution caused by livestock manure, research is needed to reduce them. Among the many factors that cause environmental and water pollution in livestock farming, phosphorus is one of the important constituents in vivo, but it is an essential nutrient for animals, but the utilization rate of phosphorus in feed is very low and it is the main culprit of environmental pollution. The use of phosphorus in animal feed shows that only 20-30% of organic phosphorus is used and the rest is excreted, resulting in severe water pollution and the addition of inorganic phosphorus to the feed due to low phosphorus utilization. In addition, the phytin of grains is also a problem such as acting as an anti-nutrient factor by combining with other nutrients or essential minerals. Therefore, in order to solve this problem, it is urgent to develop a low pollution feed that makes the best use of phosphorus acting as a potential pollutant and antinutrient in the livestock feed.

Yeast has traditionally contributed to human life with the history of alcohol and bread, and has played the most important role in the fermentation of liquor and bread. Recent advances in the natural sciences have revealed the mystery of yeast cells and their metabolism. As a result, yeast cells are not only an excellent source of nutrients for higher animals, but also an important biochemical material and a variety of useful substances by yeast metabolism. It is found that the production is possible, so that the usefulness of yeast is gradually increasing.

The usefulness of yeast is firstly that yeast can perform glycosylation which plays an important role in protein structural integrity, solubility, biological activity, etc. Second, yeast is non-pathogenic and harmless GRAS ( Generally recognized as safe) microorganisms have proven stability in food and drug production, and third, yeast can contribute to the improvement of the purification process by secreting and producing proteins extracellularly. The methylotropic yeast Pichia pastoris has the advantage of using the AOX1 promoter, a promoter with high expression rate, which is precisely regulated by methanol, and has a high concentration of cell culture. Recently, many studies have been conducted as hosts for mass expression of foreign proteins.

Phytic acid (myo-inositol 1,2,3,4,5,6-hexakisphosphate) is a major component of cereals, the most common source of poultry and pig feed. Phosphorus, in the form of phytic acid, is hydrolyzed into myo-inositol and inorganic phosphorus by the action of the myo-inositol hexaphosphate phosphohydrolase enzyme. Not only does it change, but it also increases the availability of many minerals. However, phytintaines present in more than two-thirds of these feeds were not available in the absence of phytase, a degrading enzyme in unit animals.

For this reason, phytase enzymes, like other enzymes, are used as enzyme additives in unit animal feed. Many studies have reported that the addition of phytez in feed reduces not only phosphorus availability but also the amount of organic phosphorus excreted in livestock manure. It is considered to play a sufficient role as a substitute for minerals. Therefore, the present invention was carried out to construct expression vectors for effectively producing phytez to reduce organic phosphorus, and to inject these recombinant vectors into host cell Pchia pastoris to produce phytez effectively.

The present inventors have recently discovered the use of phytez expression vectors using genetic recombination techniques as part of a method for making probiotics that produce phytase, an enzyme that breaks down phytinin in grains to reduce the environmental water pollution problems caused by livestock manure. Build it and Peachia pastoris strains were transformed to produce strains that produce recombinant phytes. Currently, most researchers use the gal promoter (Saccharomyces) Or AOX1 promoter (P. pastoris)Etc. Inducible promoters are used in the present invention for use as feed additives, and galactose or methanol may be difficult to meet in feeds or animals.PichiaThe bacterium cannot be expressed when surviving in an animal, and thus, a GAP (glyceraldeh-yde 3-phosphate dehydrogenase) promoter, which is a continuously expressed constitutive promoter, was used. Signal peptide) was used as it is to secrete out of the cells during expression.

The present invention is to prepare a primer based on the sequencing of phosphatase reported by the existing researchers that the enzyme titer studied in Pichia is high and genomic DNA in several different pitches based on this primer The fragments amplified by PCR were inserted into the yeast vector, and then transformed into mutant Peachia pastoris that cannot express phosphatase, thereby reducing the phytase activity. Measured. Conventionally, in order to mass-produce an enzyme, a method of using an inducible promoter and then purifying and adding it to a feed was used. However, the present invention is a method of adding a transformed yeast culture itself to a feed without purifying the enzyme. The production of enzyme probiotics that can express phytez continuously when not only the lutease produced but also some of the yeast passes through the animal's stomach and survives the small intestine and the large intestine, can also reduce the cost of purification in terms of production efficiency. It can be efficient.

Accordingly, an object of the present invention is to use a pitchia anomala (Pichia anomala)The present invention provides a recombinant plasmid into which a Paetez gene derived from the gene is inserted. Another object of the present invention is a novel Peach Pastoris transformed by introducing a recombinant plasmid into which the Paetez gene is inserted. To provide a yeast strain. Still another object of the present invention is to provide a recombinant phytase enzyme produced by the yeast strain.

The above object of the present invention is a peach anomala (Pichia anomala)Derived phytase gene was amplified only by PCR and inserted into the yeast vector to construct a vector for phytase expression. Peachia Pastoris (Pichia pastorisA) transformed into a yeast strain, transformed and cultured to obtain a transformant, and then cultured the transformant to investigate the production of the protein according to the expression of the Paetez gene and to produce and transform the transformed yeast strain.

Figure 1 is a schematic diagram of the production of a plasmid vector pGP1 expressing Pichia anomala phytase of the present invention.

Figure 2 shows the results of the analysis of recombinant phytase expressed and purified in Pchia pastoris - pGP1 of the present invention in an SDS-PAGE gel.

The present invention selects the Pichia pastoris (GS115) strain as a host for foreign protein production, and the step of making a pitah pastoris ( pho1 ) which is a mutant that does not express its own phosphatase; PCR amplifying a phytase gene from genomic DNA of Pichia anomala using a primer; Inserting the amplified phytez gene into the vector pGAPZαA and introducing into the E. coli Top10F 'strain, and then separating the recombinant plasmid pGP1 capable of expressing phytez from the transformant; Transforming the Pchia pastoris ( pho1 ) yeast strain with the recombinant plasmid pGP1; The transformed Pchia pastoris ( pho1 ) -pGP1 yeast strain colonies (colonies) were cultured in a medium containing an antibiotic Zeocin to select transformants and the Pchia pastoris ( pho1 ) -pGP1 Assaying that yeast strain colonies are transformants; After culturing the transformant Peachia pastoris ( pho1 ) -pGP1 yeast strain, the culture medium is composed of the step of confirming the expression of the phytase with a phytase screening solution (PSS) and measuring the expression amount.

Hereinafter, the specific method of the present invention will be described in detail with reference to Examples, but the scope of the present invention is not limited only to these Examples.

Example 1 Peachia Pastoris ( Pichia pastoris)- The GS115 strain was selected as a host for foreign protein production and mutant pichia pastoris, which does not express its own phosphatase ( Pichia pastoris (pho1)) Development of the strain

Nutrient requesting strain Pichia pastoris- GS115 lacking histidine dehydrogenase activity was used as a test strain through a literature review and microorganisms such as KCTC and ATCC. Peachia Pastoris-GS115 strain washes cells cultured in YPD medium twice with 50 mM EDTA and once with distilled water, and then spreads 15,000 cells in YPD plate medium for 30 seconds, 1 minute, 1 minute 30 seconds under UV. After exposure to 2 minutes, incubated at 30 ° C. and cloned on another YPD plate medium using a velvet cloth, PSS solution was poured into the medium to select brown colonies that do not turn brown. The selected colonies were grown on YPD medium and subjected to phosphatase and phytase analysis with wild type Peachia pastoris-GS115 to mutate phosphatase ( pho1 ). Was selected.

Example 2 Preparation of Recombinant Vectors and Transformed Strains for Producing Pytease from Peachia Anomala

First step: PCR amplification of the Peachia anomala Paitez gene using primers

Based on the Pho 1 sequence of Pichia angusta (= Hansenula polymorpha ), a primer was prepared as follows and PCR amplification was performed using the primer.

Primer for PCR amplification of Fightez

HPPN: 5'-TTT TTCGAA ACGATGTTTTCC-3 '(21mer)

Spu i

HPPC: 5'- TTTT CTCGAG TTTAGTTGTTCT-3 '(22mer)

Xho I

Each primer was artificially added to the Sfu I / Xho I recognition site to be inserted into the Sfu I and Xho I site of the pGAPZαA vector. PCR conditions were denatured at 94 ° C. for 3 minutes, followed by 30 cycles of PCR amplification. Denaturation at 95 ° C for 30 seconds, annealing at 58 ° C for 30 seconds, extension at 72 ° C for 100 seconds and last extension at 72 ° C 5 minutes at. DNA amplified by PCR was confirmed by determining agarose gel electrophoresis and gene sequence. The phytez sequence derived from Peachia anomala shows 95% homology with the Pho 1 sequence of Peacha angusta ( = Hansenula polymorpha ), which is known to be a homologous enzyme. However, Pchia angusta Pho 1 is known only as a phosphatase, which is quite different from what is found in the study for the present invention (see step 6).

Second step: constructing an expression vector by inserting the amplified Pitez gene into vector pGAPZ αA

The Pitez gene amplified by PCR was subjected to Sfu I / Xho I restriction enzyme treatment. Similarly, the pGAPZαA vector was treated with the same restriction enzyme Sfu I / Xho I restriction enzyme and then inserted. The ligation product was mixed into 100 µl of competent cells, put into 0.2 cm cuvettes, and transformed by electroporation at 400 ohms, 25 Hz, 6.25 KV / cm. After transformation, the culture of E. coli was adjusted to pH 7.5 with low salt LB medium (10 g tryptone, 5 g sodium chloride (NaCl), 5 g yeast extract per liter) using 10N sodium hydroxide (NaOH) and antibiotic preparation. Zeocin was incubated in agar medium with 25 μg per ml added to the medium. After extracting the plasmid DNA from the transformant, the DNA sequencing was confirmed to finally select a recombinant plasmid pGP1 vector capable of expressing Paetez (FIG. 1).

Stage 3: Peachia Pastoris (pho1) Transformation

10 ug of purified pGP1 DNA was transformed into Peach Pastoris (pho1) , a yeast to be used as a host. The DNA is first digested with Avr I restriction enzymes and made linear. The host strain Peachia pastoris (pho1) was inoculated in 50 mL of YPD medium and incubated overnight at 30 ° C., and then inoculated with 0.5 mL of the culture in 500 mL of YPD medium and cultured until OD ₆₀₀ became 1.3. After centrifugation at 1,500 × g for 5 minutes at 4 ° C., suspended in 500 mL of cold sterilized distilled water, centrifuged under the same conditions, and the same process was repeated with 250 mL of cold sterilized distilled water. The final volume was 1.5 mL. Competent cells were made. 80 μl of the competent cells and 10 μg of linearized DNA were mixed, placed in a 0.2 cm electroporation cuvette, allowed to stand on ice for 5 minutes, followed by electroporation at 1500 volt and 200 Ω for transformation. I was. Immediately thereafter, 1 mL of 1 M sorbitol was poured, transferred to sterile microcentrifuge tubes, laid on a YPD plate, and incubated at 30 ° C. until colonies formed.

Step 4: Selection of Pchia Pastoris Transformant

In this step, the screening process of step 1 was performed to confirm whether the colony formed in step 3 is a transformant. The surviving transformants were selected by smearing on YPD / zeosin medium using the fact that the zeocin resistant gene contained in the vector is resistant to the zeocin present in the medium. Next, pour the transformed colonies into the Pitez selection solution (PSS; α-naphtyl phosphate 0.1% (W / V), Fast Garnet GBC salts 0.2% (W / V), 0.6M acetate buffer (pH5.5)). Colonies that turn brown were selected and named Pchia Pastoris-pGP1. The present inventors deposited the strain under the accession number KCTC 18024P dated June 19, 2000 in the microbial deposit center of the Korea Institute of Science and Technology.

Step 5: Investigate whether Pitiaz expression of Pchia Pastoris pGP1

In this step, a phytase assay was performed using the method of Hartingsveldt WV, et al (1987). A phytez culture sample was placed in a reagent containing 0.25 M Naacetate pH 5.0 and 1 mM Na phytate (Sigma) to 1 ml and reacted at 40 ° C. for 30 minutes, followed by 2 ml of reagent (10 mM ammonium). molybdate: 5N H ₂ SO ₄ : acetone was mixed in a 1: 1: 2 ratio just before use), and the reaction was stopped by adding 200 μl 1M citric acid to measure the absorbance at 405 nm.

Step 6: Purification and Enzymatic Characterization of Pchia Pastoris pGP1 Pitez

Pchia Pastoris-pGP1 was inoculated in 100 ml of YPD and grown at 30 ° C. for 36 hours, followed by centrifugation. It was attached to Q6-column, an anion exchange resin buffered with acetate buffer pH4.5, washed with two volumes of the same buffer, and purified by elution with 0.3 M NaCl (see Table 1). The purified protein was analyzed by polyacrylamide gel electrophoresis (SDS-PAGE) including SDS, an anionic detergent, and found to have a molecular weight of 67 kDa and to be purified purely (FIG. 2). SDS-PAGE lanes 1-3 of the Phytez purified from Toris-pGP1; Independently from three clones, phytes were injected into Q6-column and analyzed on 10% SDS-PAGE gels. The amount of protein in the gel was twice on the right side. Peach Pastoris-GS115 StrainPho1The enzyme has a molecular weight of 80-100 kDa and is larger than the enzyme isolated from Pchia pastoris-pGP1.Pho1Since the strain was unable to express the enzyme purified above was confirmed that the transformed recombinant phytze was isolated from Peachia anomala. The strain of the present invention secretes 7,700 units of phytase into the medium when cultured in 1L YPD medium and has 12,600 units in the cell wall, thus expressing a total of 20,300 units, which is about 20 times higher than Peachia Storris-GS115 strain before transformation. Highly expressed Fightes. The optimum pH of the isolates was 5.0 and the optimum temperature was 60-65 ° C. In addition, the expression of phytez in a large amount in a phosphorus-rich medium such as YPD medium is significantly different from that of general yeast. Because of its secretion, it can be said that its economic value is great. In addition, the yeast strain of the present invention continuously produces phytes and has the advantage that it can be produced in the intestine when provided to the animal as a feed additive. Also the same species PeachiaPichia)By transforming the phytase derived from Pychiae to transformed into Peachia derived from the existing bacteria (bacteria) can be said to be much better in terms of enzyme production or stability.

Purification of recombinant phytase expressed in P. pastoris pGP1 division Protein concentration Enzyme titers Specific activity Tablet drainage Recovery rate Supernatant 0.1mg / ml 7.7 U / ml (680 U / total) 77U / mg One 100% After purification 0.74mg / ml 244U / ml (610U / total) 329U / mg 4.2 89% [Note] The reaction was performed at pH 5.0 and 60 ℃ for 30 minutes, and 1 unit was defined as the amount of enzyme capable of separating 1μmol of inorganic phosphorus per minute.

As mentioned above, the present invention is effective in producing a large amount of recombinant phytase enzyme having excellent stability by introducing and transforming the pGP1 vector into Pichia pastoris yeast strain. In addition, by adding the yeast strain to the feed directly to the unit animal, it is possible to produce enzymes in the intestine, thereby reducing the purification cost of the enzyme, and when using the yeast strain of the present invention as a feed additive, Since there is an excellent effect of reducing the amount of phosphorus excretion to reduce environmental pollution, the present invention is a very useful invention in the animal feed industry and environmental conservation industry.

Claims (4)

Recombinant plasmid vector pGP1 comprising fragments of the phytase gene from Pichia anomala and parts thereof Transformed Pchia pastoris Pichia- (pastoris (pho1))- pGP1 yeast strain (Accession No. KCTC 18024P) into which the recombinant plasmid vector pGP1 of claim 1 containing the phytase gene was introduced. Recombinant phytase enzyme expressed from the yeast strain according to claim 2 into which the recombinant plasmid vector pGP1 containing a phytase gene derived from Pichia anomala is introduced. Unit animal feed containing the transformed yeast strain (Accession No. KCTC 18024P) according to claim 2