Showing papers on "Pichia pastoris published in 1999"
TL;DR: Yeast and most higher eukaryotes utilize an evolutionarily conserved N-linked oligosaccharide biosynthetic pathway that involves the formation of a Glc3Man9GlcNAc2-PP-dolichol lipid-linked precursor, the glycan portion of which is co-translationally transferred in the endoplasmic reticulum to suitable Asn residues on nascent polypeptides.
417 citations
TL;DR: This review is a summary of the current state of knowledge of glycosylation of proteins in this methylotrophic yeast.
Abstract: The Pichia pastoris system for expression of heterologous recombinant proteins is being used increasingly because of the large yields of properly folded proteins that result and the ease of scaling preparations into large-biomass fermentors. Another advantage of this system centres on the type of glycosylation that results, generally yielding protein-bound oligosaccharides that are of much shorter chain length than found in Saccharomyces cerevisiae. This review is a summary of the current state of knowledge of glycosylation of proteins in this methylotrophic yeast.
311 citations
TL;DR: Recombinant non‐hydroxylated gelatins based on mouse type I and rat type III collagen sequences were secreted from the methylotrophic yeast Pichia pastoris, using the Saccharomyces cerevisiae α‐mating factor prepro signal to represent the highest level of heterologous protein secretion reported to date for P. pastoris.
Abstract: Recombinant non-hydroxylated gelatins based on mouse type I and rat type III collagen sequences were secreted from the methylotrophic yeast Pichia pastoris, using the Saccharomyces cerevisiae alpha-mating factor prepro signal. Proteolytic degradation could be minimized to a large extent by performing fermentations at pH 3.0 and by adding casamino acids to the medium, even though gelatin is extremely susceptible to proteolysis due to its open, unfolded structure. Proteolytic cleavage at specific mono-arginylic sites, by a putative Kex2-like protease, could be successfully abolished by site-directed mutagenesis of these sites. Production levels as high as 14.8 g/l clarified both were obtained, using multicopy tranformants. To our knowledge, this represents the highest level of heterologous protein secretion reported to date for P. pastoris.
278 citations
TL;DR: The detergent solubilisation of the fenugreek galactosyltransferase with retention of activity, the identification on gels of a putative 51 kDa galactOSyl transferase protein, and the isolation, cloning and sequencing of the corresponding cDNA are reported.
Abstract: Galactomannan biosynthesis in vitro is catalysed by membrane preparations from developing fenugreek seed endosperms. Two enzymes interact: a GDP-mannose dependent (1→4)-β-d-mannan synthase and a UDP-galactose dependent (1→6)-α-d-galactosyltransferase. The statistical distribution of galactosyl substituents along the mannan backbone, and the degree of galactose substitution of the primary product of galactomannan biosynthesis appear to be regulated by the specificity of the galactosyltransferase. We now report the detergent solubilisation of the fenugreek galactosyltransferase with retention of activity, the identification on gels of a putative 51 kDa galactosyltransferase protein, and the isolation, cloning and sequencing of the corresponding cDNA. The solubilised galactosyltransferase has an absolute requirement for added acceptor substrates. Beta-(1→4)-linked d-manno-oligosaccharides with chain lengths greater than or equal to 5 acted as acceptors, as did galactomannans of low to medium galactose-substitution. The putative galactosyltransferase cDNA encodes a 51282 Da protein, with a single transmembrane alpha helix near the N terminus. We have also confirmed the identity of the galactosyltransferase by inserting the cDNA in frame into the genome of the methylotrophic yeast Pichia pastoris under the control of an AOX promoter and the yeast alpha secretion factor and observing the secretion of galactomannan α-galactosyltransferase activity. Particularly high activities were observed when a truncated sequence, lacking the membrane-spanning helix, was expressed.
194 citations
TL;DR: The major cytokinin oxidase in immature maize kernels was purified to homogeneity and identified as ckx1, a protein of approximately 57 kDa that possesses a signal peptide, eight consensus N-glycosylation sequences and a consensus FAD binding sequence.
185 citations
TL;DR: The DNA fragment isolated from E. coli in pig colon seems to encode for a new acid phosphatase/phytase and is designated as E. bacteria appA2, a recombinant protein that was able to hydrolyze phosphorus from sodium phytate and p-nitrophenyl phosphate.
161 citations
TL;DR: The isolation of a novel human cDNA encoding a type II membrane protein of 79.5 kDa with amino acid sequence similarity to Class I alpha 1,2-mannosidases is reported, likely to be involved in glycoprotein quality control since there is increasing evidence that trimming of Man9Glc NAc2 to Man8GlcNAc2 isomer B in yeast cells is important to target misfolded glycoproteins for degradation.
Abstract: We report the isolation of a novel human cDNA encoding a type II membrane protein of 79.5 kDa with amino acid sequence similarity to Class I alpha 1,2-mannosidases. The catalytic domain of the enzyme was expressed as a secreted protein in Pichia pastoris. The recombinant enzyme removes a single mannose residue from Man9GlcNAc and [1H]-NMR analysis indicates that the only product is Man8GlcNAc isomer B, the form lacking the middle-arm terminal alpha 1,2-mannose. Calcium is required for enzyme activity and both 1-deoxymannojirimycin and kifunensine inhibit the human alpha 1,2-mannosidase. The properties and specificity of this human alpha 1,2-mannosidase are identical to the endoplasmic reticulum alpha 1,2-mannosidase from Saccharomyces cerevisiae and differ from those of previously cloned Golgi alpha 1,2-mannosidases that remove up to four mannose residues from Man9GlcNAc2 during N-glycan maturation. Northern blot analysis showed that all human tissues examined express variable amounts of a 3 kb transcript. This highly specific alpha 1,2-mannosidase is likely to be involved in glycoprotein quality control since there is increasing evidence that trimming of Man9GlcNAc2 to Man8GlcNAc2 isomer B in yeast cells is important to target misfolded glycoproteins for degradation.
142 citations
TL;DR: Glycosylation was vital to the biosynthesis of the phyA phytase in P. pastoris and the thermostability of the expressed enzyme.
140 citations
TL;DR: An assembly polymerase chain reaction (PCR) method is optimized for the fast and extremely accurate synthesis of a 2.1 kb Plasmodium falciparum gene (pfsub-1) encoding a subtilisin-like protease and is believed to be of special interest as it is simple, accessible and has no limitation with respect to the size of the gene to be synthesized.
Abstract: The A+T-rich genome of the human malaria parasite Plasmodium falciparum encodes genes of biological importance that cannot be expressed efficiently in heterologous eukaryotic systems, owing to an extremely biased codon usage and the presence of numerous cryptic polyadenylation sites. In this work we have optimized an assembly polymerase chain reaction (PCR) method for the fast and extremely accurate synthesis of a 2.1 kb Plasmodium falciparum gene (pfsub-1) encoding a subtilisin-like protease. A total of 104 oligonucleotides, designed with the aid of dedicated computer software, were assembled in a single-step PCR. The assembly was then further amplified by PCR to produce a synthetic gene which has been cloned and successfully expressed in both Pichia pastoris and recombinant baculovirus-infected High Five(TM) cells. We believe this strategy to be of special interest as it is simple, accessible and has no limitation with respect to the size of the gene to be synthesized. Used as a systematic approach for the malarial genome or any other A + T-rich organism, the method allows the rapid synthesis of a nucleotide sequence optimized for expression in the system of choice and production of sufficiently large amounts of biological material for complete molecular and structural characterization.
135 citations
TL;DR: It is proposed that GSA7 is not required for initiation of autophagy but is required for bringing the opposing vacuolar membranes together for homotypic fusion, thereby completing peroxisome sequestration.
Abstract: Cytosolic and peroxisomal enzymes necessary for methanol assimilation are synthesized when Pichia pastoris is grown in methanol. Upon adaptation from methanol to a glucose environment, these enzymes are rapidly and selectively sequestered and degraded within the yeast vacuole. Sequestration begins when the vacuole changes shape and surrounds the peroxisomes. The opposing membranes then fuse, engulfing the peroxisome. In this study, we have characterized a mutant cell line (glucose-induced selective autophagy), gsa7, which is defective in glucose-induced selective autophagy of peroxisomes, and have identified the GSA7 gene. Upon glucose adaptation, gsa7 cells were unable to degrade peroxisomal alcohol oxidase. We observed that the peroxisomes were surrounded by the vacuole, but complete uptake into the vacuole did not occur. Therefore, we propose that GSA7 is not required for initiation of autophagy but is required for bringing the opposing vacuolar membranes together for homotypic fusion, thereby completing peroxisome sequestration. By sequencing the genomic DNA fragment that complemented the gsa7 phenotype, we have found that GSA7 encodes a protein of 71 kDa (Gsa7p) with limited sequence homology to a family of ubiquitin-activating enzymes, E1. The knockout mutant gsa7Δ had an identical phenotype to gsa7, and both mutants were rescued by an epitope-tagged Gsa7p (Gsa7-hemagglutinin [HA]). In addition, a GSA7 homolog, APG7, a protein required for autophagy in Saccharomyces cerevisiae, was capable of rescuing gsa7. We have sequenced the human homolog of GSA7 and have shown many regions of identity between the yeast and human proteins. Two of these regions align to the putative ATP-binding domain and catalytic site of the family of ubiquitin activating enzymes, E1 (UBA1, UBA2, and UBA3). When either of these sites was mutated, the resulting mutants [Gsa7(ΔATP)-HA and Gsa7(C518S)-HA] were unable to rescue gsa7 cells. We provide evidence to suggest that Gsa7-HA formed a thio-ester linkage with a 25–30 kDa protein. This conjugate was not observed in cells expressing Gsa7(ΔATP)-HA or in cells expressing Gsa7(C518S)-HA. Our results suggest that this unique E1-like enzyme is required for homotypic membrane fusion, a late event in the sequestration of peroxisomes by the vacuole.
135 citations
TL;DR: Sequencing of the cDNA for the novel laccase gene lcc2 from the lignin-degrading basidiomycete Trametes versicolor showed that it encodes an isoenzyme of 499 amino-acid residues preceded by a 21-residue signal peptide, which is a conserved feature of T.versicolor isoenzymes.
Abstract: Laccase can be used for enzymatic detoxification of lignocellulosic hydrolysates. A Saccharomyces cerevisiae strain with enhanced resistance to phenolic inhibitors and thereby improved ability to ferment lignocellulosic hydrolysates would presumably be obtained by heterologous expression of laccase. Sequencing of the cDNA for the novel laccase gene lcc2 from the lignin-degrading basidiomycete Trametes versicolor showed that it encodes an isoenzyme of 499 amino-acid residues preceded by a 21-residue signal peptide. By comparison with Edman degradation data, it was concluded that lcc2 encodes an isoenzyme corresponding to laccase A. The gene product of lcc2 displays 71% identity with the previously characterized T. versicolor lcc1 gene product. An alignment of laccase sequences revealed that the T. versicolor isoenzymes in general are more closely related to corresponding isoenzymes from other white-rot fungi than to the other T. versicolor isoenzymes. The multiplicity of laccase is thus a conserved feature of T. versicolor and related species of white-rot fungi. When the T. versicolor lcc2 cDNA was expressed in S. cerevisiae, the production of active enzyme was strongly dependent on the temperature. After 3 days of incubation, a 16-fold higher laccase activity was found when a positive transformant was kept at 19 °C instead of 28 °C. Similar experiments with Pichia pastoris expressing the T. versicolor laccase gene lcc1 also showed that the expression level was favoured considerably by lower cultivation temperature, indicating that the observation made for the S. cerevisiae expression system is of general significance.
01 Jan 1999
TL;DR: This book discusses how to select a Suitable Expression System for Protein Expression in Genomics and the Future of Protein Expression Systems, and some examples of systems used in the past and those currently in use.
Abstract: Contributors. Introduction: The Art of Expression. Purpose of This Book. Selecting a Suitable Expression System: Considerations. Genomics and the Future of Protein Expression Systems, J.M. Fernandez and J.P. Hoeffler. Prokaryotic Expression Systems: Gene Expression Systems Based on Bacteriophage T7 RNA Polymearse, R. Durbin. Expression Vectors Employing the trc Promoter, J. Brosius. Bacillus Expression: A Gram Positive Model, E. Ferrari and B. Miller. araB Expression System in Escherichia coli, M. Better. Eukaryotic Expression Systems: Adenoviral Vectors for Protein Expression, D.J. von Seggern and G.R. Nemerow. Expression in the Methalotrophic Yeast Pichia pastoris, J.M. Cregg. Recombinant Protein Expression in Pichia methanolica, C.K. Raymond. Cytomegalovirus Promoter for Expression in Mammalian Cells, M.F. Stinski. Inducible Mammalian Expression Systems, M.Russell. Protein Expression in Mammalian Cells Using Sindbis Virus, R.P. Bennett. Expression in Insect Systems: Drosophila S2 System for Heterologous Gene Expression, R.B. Kirkpatrick and A. Shatzman. Baculovirus Expression Vector System, M. Galleno and A.J. Sick. Transgenic Expression: Recombinant Protein Expression in Transgenic Mice, R. Abbud and J.H. Nilson. Expression of Recombinant Proteins in the Milk of Transgenic Animals, H.M. Meade, Y. Echelard, C.A. Ziomek, M.W. Young, M. Harvey, E.S. Cole, S. Groet, T.E. Smith, and J.M. Curling. Recombinant Protein Expression in Plants, A.E. Voloudakis, Y. Yin, and R.N. Beachy. Index.
TL;DR: The PHA-E signal peptide directed correct processing and secretion of both GNA and green fluorescent protein (GFP) when used in expression constructs, and is suggested to have general utility for synthesis of correctly processed proteins in Pichia.
Abstract: Phytohemagglutinin (Phaseolus vulgaris agglutinin; PHA; E- and L-forms) and snowdrop lectin (Galanthus nivalis agglutinin; GNA) were expressed in Pichia pastoris using native signal peptides, or the Saccharomyces alpha-factor preprosequence, to direct proteins into the secretory pathway. PHA and GNA were present as soluble, functional proteins in culture supernatants when expressed from constructs containing the alpha-factor preprosequence. The recombinant lectins, purified by affinity chromatography, agglutinated rabbit erythrocytes at concentrations similar to the respective native lectins. However, incomplete processing of the signal sequence resulted in PHA-E, PHA-L and GNA with heterogenous N-termini, with the majority of the protein containing N-terminal extensions derived from the alpha-factor prosequence. Polypeptides in which most of the alpha-factor prosequence was present were also glycosylated. Inclusion of Glu-Ala repeats at the C-terminal end of the alpha-factor preprosequence led to efficient processing N-terminal to the Glu-Ala sequence, but inefficient removal of the repeats themselves, resulting in polypeptides with heterogenous N-termini still containing N-terminal extensions. In contrast, PHA expressed with the native signal peptide was secreted, correctly processed, and also fully functional. No expression of GNA from a construct containing the native GNA signal peptide was observed. The PHA-E signal peptide directed correct processing and secretion of both GNA and green fluorescent protein (GFP) when used in expression constructs, and is suggested to have general utility for synthesis of correctly processed proteins in Pichia.
TL;DR: In vitro enzyme assays with cell-free extracts of the transgenic E. coli strains showed that the genes encode UDP-glucose:sterol glucosyltransferases which can use different sterols such as cholesterol, sitosterol, and ergosterol as sugar acceptors and prove that sterol glucOSide synthesis is an inherent feature of eukaryotic microorganisms.
TL;DR: Biochemical and spectroscopic characterization of the mutant enzymes supports structural correlations between galactose oxidase and glyoxal oxidase, clearly identifying the catalytically important residues in Glyoxal oxidation and demonstrating the functions of each of these residues.
TL;DR: Formulation of an 83 amino acid fragment of thrombomodulin with two N-linked glycosylation sites shows that fermentation is more cost effective than shake flask growth for isotopic enrichment.
Abstract: Heterologous expression in Pichia pastoris has many of the advantages of eukaryotic expression, proper folding and disulfide bond formation, glycosylation, and secretion. Contrary to other eukaryotic systems, protein production from P.pastoris occurs in simple minimal defined media making this system attractive for production of labeled proteins for NMR analysis. P.pastoris is therefore the expression system of choice for NMR of proteins that cannot be refolded from inclusion bodies or that require post-translational modifications for proper folding or function. The yield of expressed proteins from P.pastoris depends critically on growth conditions, and attainment of high cell densities by fermentation has been shown to improve protein yields by 10–100-fold. Unfortunately, the cost of the isotopically enriched fermentation media components, particularly 15NH4OH, is prohibitively high. We report fermentation methods that allow for both 15N- labeling from (15NH4)2SO4 and 13C-labeling from 13C-glucose or 13C-glycerol of proteins produced in Pichia pastoris. Expression of an 83 amino acid fragment of thrombomodulin with two N-linked glycosylation sites shows that fermentation is more cost effective than shake flask growth for isotopic enrichment.
TL;DR: Biochemical and immunofluorescence microscopy analyses of pex19Delta cells identified the membrane protein Pex3p in peroxisome remnants that were not previously observed in S. cerevisiae, suggesting that Pex19p functions at an early stage of peroxISome biogenesis.
Abstract: We report the cloning and characterization of Pichia pastoris PEX19 by complementation of a peroxisome-deficient mutant strain. Import of peroxisomal targeting signal 1- and 2-containing peroxisomal matrix proteins is defective in pex19 mutants. PEX19 encodes a hydrophilic 299-amino acid protein with sequence similarity to Saccharomyces cerevisiae Pex19p and human and Chinese hamster PxF, all farnesylated proteins, as well as hypothetical proteins from Caenorhabditis elegans and Schizosaccharomyces pombe. The farnesylation consensus is conserved in PpPex19p but dispensable for function and appears unmodified under the conditions tested. Pex19p localizes predominantly to the cytosolic fraction. Biochemical and two-hybrid analyses confirmed that Pex19p interacts with Pex3p, as seen in S. cerevisiae, but unexpectedly also with Pex10p. Two-hybrid analysis demonstrated that the amino-terminal 42 amino acids of Pex19p interact with the carboxyl-terminal 335 amino acids of Pex3p. In addition, the extreme carboxyl terminus of Pex19p (67 amino acids) is required for interaction with the amino-terminal 380 amino acids of Pex10p. Biochemical and immunofluorescence microscopy analyses of pex19Delta cells identified the membrane protein Pex3p in peroxisome remnants that were not previously observed in S. cerevisiae. These small vesicular and tubular (early) remnants are morphologically distinct from other Pppex mutant (late) remnants, suggesting that Pex19p functions at an early stage of peroxisome biogenesis.
TL;DR: A Pichia pastoris mutant that was unable to grow on the peroxisome-requiring media, methanol and oleate was isolated and cloning the gene by complementation revealed that the encoded protein, Pex22p, is a new peroxin.
Abstract: We isolated a Pichia pastoris mutant that was unable to grow on the peroxisome-requiring media, methanol and oleate. Cloning the gene by complementation revealed that the encoded protein, Pex22p, is a new peroxin. A Δpex22 strain does not grow on methanol or oleate and is unable to import peroxisomal matrix proteins. However, this strain targets peroxisomal membrane proteins to membranes, most likely peroxisomal remnants, detectable by fluorescence and electron microscopy. Pex22p, composed of 187 amino acids, is an integral peroxisomal membrane protein with its NH2 terminus in the matrix and its COOH terminus in the cytosol. It contains a 25–amino acid peroxisome membrane-targeting signal at its NH2 terminus. Pex22p interacts with the ubiquitin-conjugating enzyme Pex4p, a peripheral peroxisomal membrane protein, in vivo, and in a yeast two-hybrid experiment. Pex22p is required for the peroxisomal localization of Pex4p and in strains lacking Pex22p, the Pex4p is cytosolic and unstable. Therefore, Pex22p anchors Pex4p at the peroxisomal membrane. Strains that do not express Pex4p or Pex22p have similar phenotypes and lack Pex5p, suggesting that Pex4p and Pex22p act at the same step in peroxisome biogenesis. The Saccharomyces cerevisiae hypothetical protein, Yaf5p, is the functional homologue of P. pastoris Pex22p.
TL;DR: The yeasts Pichia pastoris and Saccharomyces cerevisiae have similar overall features regarding the secretory expression of insulin, but P. pastoris has a capacity for secretORY expression of the insulin precursor that is equal to or better than that of S. Cerevisiae.
Abstract: The yeasts Pichia pastoris and Saccharomyces cerevisiae have similar overall features regarding the secretory expression of insulin. The S. cerevisiae mating factor alpha (alpha-factor) prepro-leader facilitated the secretion of an insulin precursor, but not proinsulin expressed in P. pastoris. Synthetic prepro-leaders developed for the secretory expression of the insulin precursor in S. cerevisiae also facilitated the secretion of the insulin precursor expressed in P. pastoris. In contrast with S. cerevisiae, only insulin precursor and no unprocessed hyperglycosylated alpha-factor pro-leader/insulin precursor fusion protein was secreted from P. pastoris. A spacer peptide in the fusion protein increased the fermentation yield of the insulin precursor in P. pastoris. A synthetic prepro-leader, but not an alpha-factor prepro-leader lacking N-glycosylation sites, facilitated the secretion of the insulin precursor in P. pastoris. P. pastoris has a capacity for secretory expression of the insulin precursor that is equal to or better than that of S. cerevisiae. Peptide mapping and MS indicated a structure of the insulin precursor expressed in P. pastoris identical with that of human insulin.
TL;DR: These results demonstrate for the first time that the rate of electron transfer between an oxidoreductase and an electrode can be enhanced by changes to the primary structure of a protein via site-directed mutagenesis.
Abstract: The cDNA that encodes an isoform of laccase from Trametes versicolor (LCCI), as well as a truncated version (LCCIa), was subcloned and expressed by using the yeast Pichia pastoris as the heterologous host. The amino acid sequence of LCCIa is identical to that of LCCI except that the final 11 amino acids at the C terminus of LCCI are replaced with a single cysteine residue. This modification was introduced for the purpose of improving the kinetics of electron transfer between an electrode and the copper-containing active site of laccase. The two laccases (LCCI and LCCIa) are compared in terms of their relative activity with two substrates that have different redox potentials. Results from electrochemical studies on solutions containing LCCI and LCCIa indicate that the redox potential of the active site of LCCIa is shifted to more negative values (411 mV versus normal hydrogen electrode voltage) than that found in other fungal laccases. In addition, replacing the 11 codons at the C terminus of the laccase gene with a single cysteine codon (i.e., LCCI→LCCIa) influences the rate of heterogeneous electron transfer between an electrode and the copper-containing active site (khet for LCCIa = 1.3 × 10−4 cm s−1). These results demonstrate for the first time that the rate of electron transfer between an oxidoreductase and an electrode can be enhanced by changes to the primary structure of a protein via site-directed mutagenesis.
TL;DR: High-level secreted expression (over 50 mg/liter) of the Plasmodium vivax AMA-1 (PV66/AMA-1) ectodomain is described for the first time by using the methylotrophic yeast Pichia pastoris to prevent nonnative glycosylation.
Abstract: The apical membrane antigen 1 (AMA-1) family is a promising family of malaria blood-stage vaccine candidates that have induced protection in rodent and nonhuman primate models of malaria. Correct conformation of the protein appears to be essential for the induction of parasite-inhibitory responses, and these responses appear to be primarily antibody mediated. Here we describe for the first time high-level secreted expression (over 50 mg/liter) of the Plasmodium vivax AMA-1 (PV66/AMA-1) ectodomain by using the methylotrophic yeast Pichia pastoris. To prevent nonnative glycosylation, a conservatively mutagenized PV66/AMA-1 gene (PV66Dglyc) lacking N-glycosylation sites was also developed. Expression of the PV66Dglyc ectodomain yielded similar levels of a homogeneous product that was nonglycosylated and was readily purified by ionexchange and gel filtration chromatographies. Recombinant PV66Dglyc43‐487 was reactive with conformationdependent monoclonal antibodies. With the SBAS2 adjuvant, Pichia-expressed PV66Dglyc43‐487 was highly immunogenic in five rhesus monkeys, inducing immunoglobulin G enzyme-linked immunosorbent assay titers in excess of 1:200,000. This group of monkeys had a weak trend showing lower cumulative parasite loads following a Plasmodium cynomolgi infection than in the control group.
TL;DR: The KEX1 disruption strain may be a useful tool for the expression of other proteins with a C‐terminal basic amino acid, and addition of a lysine to the C-terminus of recombinant proteins may protect the C‐ terminus from degradation by other carboxypeptidases.
Abstract: Endostatin is a potent angiogenesis inhibitor. In order to isolate sufficient quantities of soluble protein for in vivo studies in mice, we expressed murine endostatin in Pichia pastoris. Analysis of the expressed protein by mass spectrometry indicated that the protein was truncated. N-terminal sequence analysis determined that the N-terminus was intact, suggesting that the C-terminal lysine was missing. In Saccharomyces cerevisiae, Kex1p can cleave lysine and arginine residues from the C-terminus of peptides and proteins. We hypothesized that the KEX1 homologue in P. pastoris is responsible for the loss of the C-terminal lysine of endostatin. To test this hypothesis, we cloned and disrupted the P. pastoris KEX1 gene. Although the overall amino acid identity between the P. pastoris and the S. cerevisae Kex1p is only 36%, the amino acid residues involved in the catalytic activity or close to the active residues are highly conserved. Disruption of the KEX1 reading frame allowed expression of murine and human endostatin with the C-terminal lysine. The KEX1 disruption strain may be a useful tool for the expression of other proteins with a C-terminal basic amino acid. Addition of a lysine to the C-terminus of recombinant proteins may protect the C-terminus from degradation by other carboxypeptidases.
TL;DR: The presence of residual sorbitol in the growth medium appears to be less repressive to the alcohol oxidase promoter in this organism, providing a more forgiving means of operating mixed-feed fed-batch recombinant P. pastoris fermentations.
Abstract: Glycerol/methanol and sorbitol/methanol mixed-feed fermentation strategies for the production of recombinant proteins by Pichia pastoris were compared in order to examine sorbitol's potential as a carbon source. Although P. pastoris does have a lower cell yield on sorbitol than on glycerol, the specific rate of product formation is higher (60 μg protein g−1 dry wt ⋅ h for sorbitol/methanol, vs 45 μg protein g−1 dry wt ⋅ h for glycerol/methanol), resulting in comparable final recombinant expression levels. Importantly, the presence of residual sorbitol in the growth medium appears to be less repressive to the alcohol oxidase promoter in this organism, providing a more forgiving means of operating mixed-feed fed-batch recombinant P. pastoris fermentations.
TL;DR: Mice immunized with purified soluble hemagglutinin (HA0s) showed complete protection against a challenge with 10 LD50 of mouse-adapted homologous virus (X47), whereas all control mice succumbed.
Abstract: The A/Victoria/3/75 (H3N2-subtype ) hemagglutinin (HA) gene was engineered for expression in Pichia pastoris as a soluble secreted molecule. The HA cDNA lacking the C-terminal transmembrane anchor-coding sequence was fused to the Saccharomyces cerevisiaeα-mating factor secretion signal and placed under control of the methanol-inducible P. pastoris alcohol oxidase 1 (AOX1) promoter. Growth of transformants on methanol-containing medium resulted in the secretion of recombinant non-cleaved soluble hemagglutinin (HA0s). Remarkably, the pH of the induction medium had an important effect on the expression level, the highest level being obtained at pH 8.0. The gel filtration profile and the reactivity against a panel of different HA-conformation specific monoclonal antibodies indicated that HA0s was monomeric. Analysis of the N-linked glycans revealed a typical P. pastoris type of glycosylation, consisting of glycans with 10–12 glycosyl residues.
Mice immunized with purified soluble hemagglutinin (HA0s) showed complete protection against a challenge with 10 LD50 of mouse-adapted homologous virus (X47), whereas all control mice succumbed. Heterologous challenge with X31 virus [A/Aichi/2/68 (H3N2-subtype)], resulted in significantly higher survival rates in the immunized group compared with the control group. These results, together with the safety, reliability and economic potential of P. pastoris, as well as the flexibility and fast adaptation of the expression system may allow development of an effective recombinant influenza vaccine.
TL;DR: In this article, the optimum pH, temperature and glycerol feed rate for the production of recombinant hookworm (Ancylostoma caninum) anticoagulant peptide (rAcAP-5) by Pichia pastoris using response surface methodology (RSM).
TL;DR: A full-length cDNA encoding an acetylcholinesterase secreted by the nematode parasite Nippostrongylus brasiliensis was isolated and displayed excess substrate inhibition with acetylthiocholine at concentrations over 2.5 mm and was highly sensitive to both active site and “peripheral” site inhibitors.
TL;DR: Ag 5 from yeast was shown to have the native structure of the natural protein and the recombinant Ag 5 from bacteria did not, and by comparison of their solubility, electrophoretic behavior, disulfide bond content, CD spectrum, and binding of IgE antibodies from allergic patients and IgG antibodies from mice immunized with natural Ag 5 or recombinantAg 5s from yeast or bacteria.
TL;DR: Recombinant Ole e 1 appears to be properly folded, as it displays spectroscopic properties and immunological reactivities indistinguishable from those of the natural protein, which should be useful for scientific and clinical purposes.
Abstract: The glycoprotein Ole e 1 is a significant aeroallergen from the olive tree (Olea europaea) pollen, with great clinical relevance in the Mediterranean area. To produce a biologically active form of recombinant Ole e 1, heterologous expression in the methylotrophic yeast Pichia pastoris was carried out. A cDNA encoding Ole e 1, fused to a Saccharomyces cerevisiae alpha-mating factor prepropeptide using the pPIC9 vector, was inserted into the yeast genome under the control of the AOX1 promoter. After induction with methanol, the protein secreted into the extracellular medium was purified by ion-exchange and size-exclusion chromatography. The structure of the isolated recombinant Ole e 1 was determined by chemical and spectroscopic techniques, and its immunological properties analysed by blotting and ELISA inhibition with Ole e 1-specific monoclonal antibodies and IgE from sera of allergic patients. The allergen was produced at a yield of 60 mg per litre of culture as a homogeneous glycosylated protein of around 18.5 kDa. Recombinant Ole e 1 appears to be properly folded, as it displays spectroscopic properties (CD and fluorescence) and immunological reactivities (IgG binding to monoclonal antibodies sensitive to denaturation and IgE from sera of allergic patients) indistinguishable from those of the natural protein. This approach gives high-yield production of homogeneous and biologically active allergen, which should be useful for scientific and clinical purposes.
TL;DR: The expression of recombinant human granzyme B in Pichia pastoris is described as a chimeric zymogen comprising the alpha-factor signal sequence, a prodomain including an enterokinase cleavage site, and the mature gran enzyme B sequence followed by a hexahistidine tag.
TL;DR: Pichia pastoris may not serve as an adequate host for the site‐directed mutagenesis of T. reesei CBH I, and the yeast‐expressed enzyme showed non‐wild‐type secondary structure by circular dichroism.
Abstract: Pichia pastoris was transformed with the Trichoderma reesei cbh1 gene, and the recombinant enzyme was purified and analyzed kinetically and by circular dichroism The P pastoris rCBH I was recognized by MoAb raised to T reesei CBH I but was found in multiple molecular weight species on SDS-PAGE gels Carbohydrate content determination and SDS-PAGE western analysis indicated that the recombinant protein was hyperglycosylated, although a species very similar in molecular weight to the T reesei enzyme could be isolated chromatographically The P pastoris rCBH I also demonstrated activity toward soluble and insoluble substrates (ie, pNPL and Sigmacell), although at a level significantly lower than the wild-type enzyme More seriously, the yeast-expressed enzyme showed non-wild-type secondary structure by circular dichroism We conclude that P pastoris may not serve as an adequate host for the site-directed mutagenesis of T reesei CBH I