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Assembly of human prolyl 4-hydroxylase and type III collagen in the yeast pichia pastoris: formation of a stable enzyme tetramer requires coexpression with collagen and assembly of a stable collagen requires coexpression with prolyl 4-hydroxylase.

Prolyl 4-hydroxylase, the key enzyme of collagen synthesis, is an alpha2beta2 tetramer, the beta subunit of which is protein disulfide isomerase (PDI). Coexpression of the human alpha subunit and PDI in Pichia produced trace amounts of an active tetramer. A much higher, although still low, assembly level was obtained using a Saccharomyces pre-pro sequence in PDI. Coexpression with human type III procollagen unexpectedly increased the assembly level 10-fold, with no increase in the total amounts of the subunits. The recombinant enzyme was active not only in Pichia extracts but also inside the yeast cell, indicating that Pichia must have a system for transporting all the cosubstrates needed by the enzyme into the lumen of the endoplasmic reticulum. The 4-hydroxyproline-containing procollagen polypeptide chains were of full length and formed molecules with stable triple helices even though Pichia probably has no Hsp47-like protein. The data indicate that collagen synthesis in Pichia, and probably also in other cells, involves a highly unusual control mechanism, in that production of a stable prolyl 4-hydroxylase requires collagen expression while assembly of a stable collagen requires enzyme expression. This Pichia system seems ideal for the high-level production of various recombinant collagens for numerous scientific and medical purposes.

Collagen↗

Genetic diversity of the Pichia membranifaciens strains revealed from rRNA gene sequencing and electrophoretic karyotyping, and the proposal of Candida californica comb. nov.

The genetic diversity of the types or authentic strains of 20 facultative synonyms of Pichia membranifaciens (E.C. Hansen) E.C. Hansen was revealed on the basis of large-subunit (26S) rDNA D1/D2 domain and internal transcribed spacer region sequencing and electrophoretic karyotyping. At least five separate species were recognized among the strains studied. Fourteen strains were confirmed to belong to P. membranifaciens. Strain CBS 241, an authentic strain of Zygosaccharomyces chevalieri Guilliermond var. fermentati Saito, should be assigned to Pichia manshurica Santa María. Strain CBS 243, an authentic strain of Zygopichia chiantigiana Castelli, is conspecific with CBS 2287, the type strain of Pichia fluxuum (Phaff & Knapp) Kreger-van Rij. Strain CBS 1367, the type of Zygosaccharomyces bisporus Anderson, belongs to Pichia kluyveri Bedford var. kluyveri. Strain CBS 989, the type of Cryptococcus californicus Anderson & Skinner, represents a distinct species, for which a new combination, Candida californica comb. nov., is proposed. The taxonomic status of strains CBS 189, the type of Pichia calliphorae Klöcker, and CBS 214, the type of Pichia derossii Castelli, remain to be studied further. Their D1/D2 sequences and chromosomal DNA banding patterns were similar to those of P. membranifaciens, but their internal transcribed spacer sequences differed significantly.

Candida↗

[Expression and identification of recombinant arresten in Pichia pastoris].

Arresten as a endogenous inhibitor of angiogenesis originated from the carboxyl-terminal 223 amino acids fragment of the non-collagen domain in alpha1 chain of human collagen IV. In order to get the soluble arresten with biological activity, the cDNA of arresten was cloned and expressed in Pichia pastoris. The produced arresten cDNA was amplified by PCR using primer P1:5'-AGGCCCCGATGGGTTGC-3', primer P2:5'-CTATAAG GCACTTTACGGTTTC-3'. The PCR products was cloned into pGEM-T vector, and sequenced. The arresten cDNA from pGEM-T vector was recombined with vector pPIC9 as pPIC9-arresten, used to transform E. coli DH5alpha, and the inserted arresten cDNA confirmed by agarose electrophoresis and sequencing. pPIC9-arresten was linearized by Sac I. Pichia pastoris GS115 was treated with PEG1000 (followed Invitrogen' s specification); transformed with linear recombined pPIC9-arresten. Pichia pastoris GS115 was culured on MD mediun, single clone was selected and the DNA from the single clone was extracted, used as template, characterized by PCR using the second pair primers P3:5'-CGCTCGAGAAAAGATCTGTTGATC-3', P4:5'-GCCCCGG ATCCTTATGTTCTFCTCATACAG-3'. The polynucleotides CTCGAGAAAAGA used as marker sequence was inserted into primer P3 for signal peptidase to cleave off the signal sequence correctively. The recombined Pichia pastoris GS115 was selected according to the results of PCR, cultured on MM and MD media and then in the BMGY media using methanol as inducer. Expressed arresten was analysed by SDS-PAGE. The soluble arresten expressed by Pichia pastoris gave apparent molecular weight in SDS-PAGE consistent with that calculated, and in matrigel gel it showed inhibitary activity on the tubulation of endothelial cell ECV-304 induced by tumor cell MDA-MB-435S. These results showesd arresten with biological activity is expressed successfully in Pichia pastoris GS115.

Arrestin↗

Isolation and characterization of the TIM10 homologue from the yeast Pichia sorbitophila: a putative component of the mitochondrial protein import system.

The Saccharomyces cerevisiae TIM10 gene encodes one of the few essential mitochondrial proteins that are required for the import of nuclear-encoded precursor proteins from the cytosol and their subsequent sorting into the different mitochondrial compartments. We have isolated and characterized a putative homologue of TIM10 from the halotolerant yeast Pichia sorbitophila. The Pichia TIM10 gene encodes a protein of 90 amino acids with 66% identity to S. cerevisiae Tim10p. It was capable of suppressing the temperature sensitivity of tim10-1 mutant in S. cerevisiae, suggesting that Pichia TIM10 is both a functional and structural homologue of S. cerevisiae TIM10. The putative Pichia TIM10 gene product contains all the four conserved cysteine residues and the two CX(3)C motifs typical of the Tim family proteins in the mitochondrial intermembrane space. Using anti-Tim10p serum, Western blots detected a protein of about 10 kDa, suggesting that the Pichia Tim10p is a mitochondrial protein. The results suggest that mitochondrial import and sorting systems might be also strongly conserved in other fungi. The coding sequence of the P. sorbitophila TIM10 has been deposited in the EMBL Nucleotide Sequence Database under Accession No. AJ243940.

Amino Acid Sequence↗

DNA relatedness among saturn-spored yeasts assigned to the genera Williopsis and Pichia.

Saturn-spored species assigned to the genera Williopsis and Pichia were compared from extent of nuclear DNA complementarity. Of the Pichia spp., four were recognized as distinct taxa: P. dispora, P. saitoi, P. zaruensis and Pichia sp. nov. Among Williopsis spp., the following were accepted: W. californica, W. mucosa comb. nov., W. pratensis, W. saturnus var. saturnus, W. saturnus var. mrakii comb. nov., W. saturnus var. sargentensis comb. nov., W. saturnus var. subsufficiens comb. nov. and Williopsis sp. nov. The new Pichia and Williopsis species are described elsewhere. Moderate (36-68%) DNA relatedness was detected between the former Pichia sargentensis and varieties of W. saturnus again demonstrating that nitrate assimilation is not a reliable criterion for separating yeast species.

DNA, Fungal↗

Synonomy of the yeast genera Hansenula and Pichia demonstrated through comparisons of deoxyribonucleic acid relatedness.

The relationship between the genera Hansenula and Pichia was examined through comparisons of DNA relatedness among phenotypically similar species. Hansenula minuta and Pichia lindneri showed 75% DNA base sequence complementarity. In other comparisons, H. nonfermentans was found to share nearly 50% of its DNA sequences with both H. minuta and P. lindneri. Because of the high degree of relatedness observed, it is proposed that ability to assimilate nitrate, the sole distinction between Hansenula and Pichia, is of insufficient taxonomic value for the reliable separation of either species or genera. Hat-spored species of Hansenula H. et P. Sydow 1919 are being transferred to Pichia Hansen 1904. Species of Hansenula and Pichia with Saturn-shaped ascospores will be transferred to the genus Williopsis.

Ascomycota↗

Cloning and improving the expression of Pichia stipitis xylose reductase gene in Saccharomyces cerevisiae.

The intact Pichia stipitis xylose reductase gene (XR) has been cloned and expressed in Saccharomyces cerevisiae. The possible further improvement of the expression of the Pichia gene in the new host was studied. To improve the expression of the XR gene in yeast (Saccharomyces cerevisiae), its 5'noncoding sequence containing the genetic elements for transcription and translation was systematically replaced by that from the yeast genes. It was found that the Pichia genetic signal for transcription of XR is more effective than the yeast TRP5 promoter, but is about half as effective as the yeast strong promoter of the alcohol dehydrogenase gene (ADC1). However, the nucleotide sequence immediately adjacent to the initiation codon of XR, which controls the translation of the gene product, seemed to be five times less effective than the corresponding sequence of the ADC1 gene. By totally replacing its 5'-noncoding sequence with that of the yeast ADC1 gene, the expression of XR in yeast was found to be nearly ten times higher. Furthermore, the cloned Pichia XR described in this article contains very little of its 3'-noncoding sequence. In order to study whether the 3'-noncoding sequence is important to its expression in S. cerevisiae, the intact 3'-noncoding sequences of the yeast xylulokinase gene was spliced to the 3' end of the PADC1-XR structural gene. This latter modification has resulted in a twofold further increase in the expression of the Pichia XR in yeast.

Alcohol Dehydrogenase↗

Genetic transformation of xylose-fermenting yeast Pichia stipitis. Scientific note.

A plasmid-mediated transformation system has been developed for the xylose-fermenting yeast Pichia stipitis. We found that plasmid vectors containing the Saccharomyces cerevisiae 2 mu replicon and the kanamycin resistance gene (KmR) could be introduced into the Pichia cells and maintained as extrachromosomal elements. Pichia transformants containing such vectors will be resistant to the antibiotic geneticin that can be inactivated by the protein product of KmR. Plasmids identical to those used for transformation can be recovered from the Pichia transformants. Protocols for transformation of P. stipitis by the CaCl2-polyethylene glycol-protoplast process or by direct electroporation of intact Pichia cells have both been developed.

Escherichia coli↗

High-level expression of cockroach allergen, Bla g 4, in Pichia pastoris.

Exposure to cockroach allergens is a risk factor for allergic disease and has been linked to an increase in asthma morbidity among cockroach-sensitive inner-city children. Bla g 4 is a ligand-binding protein (or calycin) that causes IgE antibody responses in 40% to 60% of patients allergic to cockroaches. Recombinant Bla g 4 was expressed in Escherichia coli as an 18 kd protein but provided poor yields (only 0.25 mg/L culture). To improve yields, Bla g 4 was expressed in the Pichia pastoris yeast system as a 23 kd secreted protein at concentrations of 50 mg allergen/L. By cross-inhibition radioimmunoassay, Bla g 4 expressed in E. coli or P. pastoris provided overlapping inhibition curves. Both allergen preparations bound comparable levels of serum IgE antibody and showed similar skin test reactivity in individuals allergic to cockroaches (10[-1] to 10[-3] microg/ml). Deglycosylation of Pichia-expressed Bla g 4 with endoglycosidase F resulted in an 18 to 20 kd doublet, and liquid chromatography-mass spectrometry results suggested that the 20 kd band contained residual sugar residues. Both glycosylated and deglycosylated Pichia Bla g 4 showed comparable inhibition of IgE antibody binding in radioimmunoassay. Pichia-produced Bla g 4 had the same antigenic reactivity as that produced in E. coli, and glycosylation had no effect on IgE antibody binding. The high yield of Bla g 4 obtained in the Pichia system will facilitate studies on the structure and function of calycin allergens and on the immune response of asthma patients to cockroach allergens.

Allergens↗

[Improving phytase expression by increasing the gene copy number of appA-m in Pichia pastoris].

In order to improve the fermentation potency of phytase in recombinant host and decrease the production cost, the pichia expression vector pGAPZalpha-A was modified by introduction of an AOX1 promoter from vector pPIC9 and the resulted vector pAOXZalpha is an methanol induced vector. After that, a phytase gene appA-m was cloned into pAOXZalpha to construct the recombinant vector pAOXZalpha-appA-m. The recombinant Pichia pastoris 74#, which already contains one copy of appA-m and its fermentation potency exceeded 7.5 x 10(6) IU/mL, was used as the host strain for the transformation of pAOXZalpha-appA-m. The Pichia pastoris transformants were gained by electroporation. PCR results indicated that the appA-m expression box has integrated into the genome of Pichia pastoris and the original construction of phytase gene has not changed. SDS-PAGE analysis revealed that phytase was overexpressed and secreted into the medium supernatant. Recombinants with high expression level were screened and used for fermentation. In 5L fermentor, the expression level of phytase protein achieved 4 mg/mL and the phytase activity (fermentation potency) exceeded 1.2 x 10(7) IU/mL, which was about 1.6-fold compared with that of the host strain 74#. Moreover, the improved recombinant Pichia pastoris is excellent at expression stability and heredity stability.

6-Phytase↗

Pichia thermomethanolica sp. nov., a novel thermotolerant, methylotrophic yeast isolated in Thailand.

Three strains (N002, N069 and PT31(T)) of a novel thermotolerant methylotrophic yeast species belonging to the genus Pichia were isolated from soil collected in Thailand by three consecutive enrichments in methanol broth at room temperature. They were categorized as thermotolerant strains on the basis of their good growth below 20 degrees C and up to a high temperature (37 degrees C). The major characteristics of the three strains included the following and placed them in the genus Pichia: the formation of four helmet-/hat-shaped ascospores in a deliquescent ascus that might be unconjugated or produced by conjugation between a cell and its bud or between independent cells; multilateral budding; the presence of ubiquinone Q-7; negative for Diazonium blue B colour and urease reactions; and the absence of arthrospores and ballistospores. The three strains differed by one to three nucleotide substitutions in the sequences of the D1/D2 domain of the large-subunit rDNA sequence. Phylogenetic analysis revealed that their closest species was Pichia dorogensis, but with 11-13 nucleotide substitutions in 554 nt. The phenotypic characteristics of the three strains were the same. The strains could be distinguished from P. dorogensis by a number of phenotypic characteristics. On the basis of the above findings, these three strains were assigned to a single novel species of Pichia, for which the name Pichia thermomethanolica sp. nov. is proposed. The type strain is PT31(T) (=BCC 16875(T)=JCM 12984(T)=CBS 10098(T)).

DNA, Fungal↗

[Influence of signal peptide sequences on the expression of heterogeneous proteins in Pichia pastoris].

Pichia pastoris has been developed to be a very efficient expression host for the heterogeneous proteins since its alcohol promoter was isolated and cloned, and its transformation technique was established. For further improving the secretion expression of heterogeneous proteins, in this research, the signal sequences were studied. At first, the Saccharomyces cerevisiae mating factor alpha prepro-leader sequence was synthesized using successive PCR and designated as MF4I. Then, ten different signal sequences were constructed by adding the N-terminal residues of Pichia pastoris Aox1 protein to the N-terminal of the MF4I. These ten signal sequences were used for directing phytase gene secretion in Pichia pastoris, the secretion of phytase were increased in Pichia pastoris strains containing new signal sequence. Among these strains, the phytase secretion was highest in strain contain signal sequence added with A, I, P three Aox1 N-terminal residues; the phytase secretion of Pichia pastoris was 90 mg/L in flake. The secretion was six-fold of that with original Saccharomyces cerevisiae mating factor alpha prepro-leader sequence. In addition, insert of ten residues E E A E A E A E P K can further increase the phytase secretion by 35%, the secretion reach 120 mg/L.

6-Phytase↗

[Cloning of mouse TLR-2 gene and its expression in Pichia pastroris].

AIM: To clone the mouse TLR-2 gene and to express it in Pichia pastroris. METHODS: Full-length gene encoding mouse Toll-like receptor 2 (mTLR-2) was amplified by RT-PCR, cloned into pUCm-T vector, and confirmed by sequencing. The target gene was then inserted into Pichia pastroris expression vector pPICZalphaC, which was transformed into Pichia pastroris. The recombinant Pichia pastroris was confirmed by PCR and RT-PCR. Expressed protein was identified by SDS-PAGE and Western blot. RESULTS: The full-length mTLR-2 gene(GenBank accession No.AY179346) was cloned. The homology of the cloned gene to published mTLR-2 gene reached 99.84%. The recombinant expression plasmid pPICZ- mTLR-2 was constructed successfully. SDS-PAGE analysis showed that the relative molecular mass(M(r)) of recombinant protein was about 97 000. Western blot analysis showed expressed product can react to rabbit anti- mTLR-2 antibody. CONCLUSION: The full-length mTLR-2 gene is cloned and the recombinant protein can be expressed in Pichia pastroris correctly.

Animals↗

[Gene optimization is necessary to express HPV type 6 L1 protein in the methylotrophic yeast Pichia pastoris].

OBJECTIVE: Human papillomavirus 6 (HPV 6) causes genital warts, a common sexually transmitted disease. L1-capsids protein is a highly promising vaccine candidate that has entered phase II clinical trial. But the existing methodologies for producing L1-capsids in insect cells is expensive for use in developing countries. As methylotrophic yeast,the Pichia pastoris expression system offers economy,and high expression levels. Over-expression of HPV6-L1 protein in P. pastoris was the purpose of this study. METHODS: The whole L1 gene with preferred codons for P. pastoris was rebuilt and A-T rich regions were abolished, Cloning into pPIC3.5K,electroporation of KM71, in vivo screen of multiple inserts by G418 resistance, PCR analysis of pichia integrants, BMGY/BMMY are used for induction and expression of L1 proteins. RESULTS: Three clones were found to produce L1 protein which can be identified with Western blot. Compared with L1 protein from E.coli, pichia-produced L1 has some glycosylation. Reacting strongly with MabH6B10.5 in indirect immunofluorescence assay indicated that L1 protein expressed in pichia cell holds its native conformational epitopes which is important for vaccine use. A total 125 microg pure L1 protein could be obtained from 1L cultures through ion-exchange and Ni-NTA chromatography. CONCLUSION: HPV type 6 L1 protein expressed in Pichia pastoris will facilitate the HPV vaccine development and structure-function study.

Capsid Proteins↗

[Expression of phosphoprotein P2 of Cysticercus cellulosae in Pichia pastoris and its application].

Cysticercosis is caused by the metacestode form of Taenia solium-Cysticercus cellulosae and it causes great economic losses and threatens the people's health. There are some problems on how to control cysticercosis, in order to resolve the key problem that the native antigen to diagnose and prevent cysticercosis is very limited and is not satisfied, Pichia pastoris Expression System was used to express recombinant P2 protein. The interested P2 gene was got by digesting the pGEM - P2 vector using restriction endonuclease, then it was inserted into the secretory pPIC9K Pichia pastoris expression vector and transformed into E. coli. Positive recombinant plasmids were selected sequenced and named pPIC9K-P2 and it was linearized by Sal I and Bgl II, then the linear DNA transfored into Pichia pastoris GS115 by electroporation. The recombinant expression vector pPIC9K - P2 integrated into GS115 via homologous recombination between the transforming DNA and regions of homology within the genome. The transformants were screened for multicopy recombinants using G418 and were distinguished for Mut phenotypes by MD and MM. Two different phenotypes were generated-HIS+ MUT+ (Methanol utilization plus) and HIS+ MUT(S) (Methanol utilization slow). PCR analysis of the multicopy recombinants indicated that the P2 gene was integrated within the genome of pichia Pastoris. The multicopy recombinants were named GS115/pPIC9K - P2HIS+ MUT+ and GS115/pPIC9K-P2HIS+ MUT(S), both HIS+ MUT+ and HIS+ MUT(S) were induced with methanol. The results of SDS-PAGE and Western blot demonstrated that the culture supernatant of the induced Pichia pastoris contained P2 protein which was accumulated up to 33 % of total proteins in the culture supernant and its molecular weight is 12.6kD. The results of the clinical study indicated that the expression P2 protein could be used to diagnose human cysticercosis and swine cysticercosis as diagnosis antigen.

Animals↗

[Expression of recombinant human zona pellucida-3 protein (rhZP3) in Pichia pastoris].

Human Zona Pellucida(ZP), which is a complex matrix surrounding oocytes,is comprised of three immunologically distinct glycoproteins(hZP1, hZP2 and hZP3). Because hZP3 possesses the sperm receptor activity and the acrosome-inducing activity, it has long been used as a candidate antigen to develop an immunocontraceptive vaccine. However, a large amount of native hZP3 protein is unavailable. It is an effective way to express hZP3 protein directly in vitro. Nevertheless, it had been reported that the rhZP3 protein produced in Pichia pastoris was not secreted but accumulated in the cells and could only be purified after being solubilized by strong denaturants. More unfortunately, after purification the final product required 6mol/L urea to maintain solubility. An improved project was advanced with the aim to express secreted and soluble rhZP3 protein in yeast. In this study, the fragment of hZP3 cDNA coding for aa 23 - 408, which the N-terminal leader was removed and most of the C-terminal transmembrane-like domain was reserved, was amplified by two PCR primers including EcoR I and Not I sites respectively and a His6 codon cassette was added to 5'-terminal. The hZP3 insert was incorporated into expression vector pPIC9K. The resulting recombinant yeast expression vector was designated pPIC9K-rhZP3. Linearized pPIC9K-rhZP3 was transformed into Pichia pastoris. After G418 selection, the recombinant Pichia pastoris strains were identified by PCR and the rhZP3 was expressed following the manufacturer' s protocol. Following induction with methanol, the rhZP3 protein was secreted and dissolved into the culture supernatant. SDS-PAGE and Western blot analyses showed that the apparent molecular weight of the expressed rhPZ3 proteins in yeast was smaller and a little size heterogeneity than native ones; after purified with Ni-chelating affinity chromatography, the final product's apparent molecular weight was about 32 - 34KD and their yield more than 20mg/L. We supposed that the C-terminal transmembrane-like domain be useful for secretion of rhZP3 into the culture supernatant and the expressed rhZP3 protein be incompletely digested by proteinases of Pichia into shorter fragments which all were glycosylated inhomogeneously. Fortunately, the fragments of rhZP3 protein can be recognized in Western blot by the polyclonal antibodies to porcine ZP3 which has showed a cross-reactivity with human ZP in vitro. It will be expected that the rhZP3 protein expressed in Pichia pastoris not only has immunogencity, say, it can rise antibodies in vivo to prevent spermatozoa-ovum binding, but also does not contain ovarian factors that might be the cause of undesired side effects, e.g. ovaritis and can be used as a safe immunogen in human antifertility vaccine research.

Blotting, Western↗

[Codon optimization and expression in Pichia pastoris of E2 gene of classical swine fever virus].

Codon bias was one of the important parameter which influence heterogenous gene expression, optimizing codon sequence could improve expression level of heterogenous gene. In the preview study, wildtype E2 gene was expressed poorly in Pichia pastoris, in order to improve the expression level of E2 gene in Pichia pastoris, the low usage codons of E2 gene were mutated into high usage codons in Pichia pastoris by directed-mutagenesis based on PCR. The result showed that, compared with the results reported in preview study, the expression level of E2 gene in Pichia pastoris was improved observably by substituting 24 low usage codons of E2 gene for the high usage synonymous codons. It suggested the stragety to improve the expression of E2 gene in Pichia pastoris by codon optimization was successful.

Base Sequence↗

Expression of extracellular domain of human vascular endothelial growth factor receptor-2 in Pichia pastoris.

OBJECTIVE: To investigate the feasibility of high expressing extracellular domain of human vascular endothelial growth factor receptor-2 (heVEGFR-2) with eukaryotic protein structure in Pichia pastoris. METHODS: We used PCR to amplify the DNA fragment encoding heVEGFR-2 from pORF-heVEGFR-2. The recombinant Pichia pastoris secretory expression vector(pPICZalphaA-heVEGFR-2)was constructed and transferred into Pichia pastoris X-33 by electroporation. The high expression transformnants were identified through its drug-resistant phenotype and methanol induction. RESULTS: As indicated by SDS-PAGE, the recombinant heVEGFR-2 protein with a molecular weight (MW) approximately 108 kDa, which reached 80 mg/L in the mass concentration, comprised 45% of the total expressed secreted proteins from Pichia pastoris X-33. The section of heVEGFR-2 had a MW approximately 106 kDa. The results of western blot analysis demonstrated that this protein could be specifically recognized by the rat monoclonal antibody against mouse VEGFR-2 (rat McAb against mVEGFR-2). CONCLUSION: The heVEGFR-2 with eukaryotic protein structure can get a high expression in Pichia pastoris.

Animals↗