Pichia pastoris

About: Pichia pastoris is a research topic. Over the lifetime, 7937 publications have been published within this topic receiving 162645 citations. The topic is also known as: Komagataella pastoris.

Heterologous expression of Aspergillus aculeatus endo-polygalacturonase in Pichia pastoris by high cell density fermentation and its application in textile scouring.

Abstract: Removal of non-cellulosic impurities from cotton fabric, known as scouring, by conventional alkaline treatment causes environmental problems and reduces physical strength of fabrics. In this study, an endo-polygalacturonase (EndoPG) from Aspergillus aculeatus produced in Pichia pastoris was evaluated for its efficiency as a bioscouring agent while most current bioscouring process has been performed using crude pectinase preparation. The recombinant EndoPG exhibited a specific activity of 1892.08 U/mg on citrus pectin under the optimal condition at 50 °C, pH 5.0 with a V max and K m of 65,451.35 μmol/min/mL and 15.14 mg/mL, respectively. A maximal activity of 2408.70 ± 26.50 U/mL in the culture supernatant was obtained by high cell density batch fermentation, equivalent to a 4.8 times greater yield than that from shake-flask culture. The recombinant enzyme was shown to be suitable for application as a bioscouring agent, in which the wettability of cotton fabric was increased by treatment with enzyme at 300 U/mL scouring solution at 40 °C, pH 5.0 for 1 h. The bio-scoured fabric has comparable wettability to that obtained by conventional chemical scouring, but has higher tensile strength. The work has demonstrated for the first time functions of A. aculeatus EndoPG on bioscouring in eco-textile processing. EndoPG alone was shown to possess effective scouring activity. High expression level and homogeneity could be achieved in bench-scale bioreactor.

Deletion of the conserved first 18 n-terminal amino acid residues in rat liver carnitine palmitoyltransferase i abolishes malonyl-coa sensitivity and binding

Abstract: To assess the role of the 130 N-terminal amino acid residues of rat liver carnitine palmitoyltransferase I (L-CPTI) on malonyl-CoA sensitivity and binding, we constructed a series of mutants with deletions of the 18, 35, 52, 73, 83, or 129 most N-terminal amino acid residues. The deletion mutants were expressed in the yeast Pichia pastoris. We determined the effects of these mutations on L-CPTI activity, malonyl-CoA sensitivity, and binding in isolated mitochondria prepared from the yeast strains expressing the wild-type and deletion mutants. The mutant protein that lacked the first 18 N-terminal amino acid residues, Delta18, had activity and kinetic properties similar to wild-type L-CPTI, but it was almost completely insensitive to malonyl-CoA inhibition (I50 = 380 microM versus 2.0 microM). In addition, loss of malonyl-CoA sensitivity in Delta18 was accompanied by a 70-fold decrease in affinity for malonyl CoA (KD = 70 nM versus 1.1 nM) compared to wild-type L-CPTI. Deletion of the first 35, 52, 73, and 83 N-terminal amino acid residues had a similar effect on malonyl-CoA sensitivity as did the 18-residue deletion mutant, and there was a progressive reduction in the affinity for malonyl-CoA binding. By contrast, deletion of the first 129 N-terminal amino acid residues resulted in the synthesis of an inactive protein. To our knowledge, this is the first report to demonstrate a critical role for these perfectly conserved first 18 N-terminal amino acid residues of L-CPTI in malonyl-CoA sensitivity and binding.

[33] Functional expression of human P-glycoprotein from plasmids using vaccinia virus-bacteriophage T7 RNA polymerase system

Abstract: Publisher Summary This chapter describes the vaccinia-T7 expression system that has proved to be ideal for functional studies of P-glycoprotein (Pgp) and the transporter associated with multidrug resistance (MDR). The heterologous expression systems have been explored but none have been completely satisfying. The baculovirus/insect cell system appears to be most promising for the large-scale synthesis of protein for biochemical and structural analysis. The expression of human Pgp in the yeast Saccharomyces cerevisiae and E. coli have met with limited success owing to low expression levels, toxicity, or intrinsically high ATPase levels, but neither proved as versatile as the vaccinia-T7 system. Higher-level expression in the yeast Pichia pastoris appears to be feasible. The use of this vaccinia-T7 transient system that does not involve drug selection for Pgp expression eliminates the need to consider these possible complications in the interpretation of the observed phenotypes. The major drawback of the vaccinia-T7 system is that the infected transfected cells cannot be used to measure relative resistance to MDR drugs in cell proliferation assays because the infected cells are committed to virus-induced lysis.

Expression and processing of vertebrate acetylcholinesterase in the yeast Pichia pastoris.

Abstract: In the methylotrophic yeast Pichia pastoris, we expressed the rat acetylcholinesterase H and T subunits (AChEH and AChET respectively), as well as truncated subunits from rat (W553stop or AChETDelta, from which most of the T-peptide was removed) and from Bungarus (V536stop, or AChENAT, or AChEDelta, reduced to the catalytic domain). We show that AChEH and AChET subunits are processed into the same molecular forms as in vivo or in transfected mammalian cells, but that lytic processes converting amphiphilic forms into non-amphiphilic derivatives appear to be more active in yeast. The production of glycophosphatidylinositol (GPI)-anchored molecules (dimers, with a small proportion of monomers) demonstrates that P. pastoris can correctly process a mammalian C-terminal GPI-addition signal. Truncated rat and Bungarus AChE molecules, which exclusively generated non-amphiphilic monomers, were released more efficiently and thus produced more AChE activity. In the hope of increasing the production of AChE, we replaced the endogenous signal peptide by yeast prepeptides, with or without a propeptide. We found that the presence of a propeptide, which does not exist in AChE, does not prevent the proper folding of the enzyme, and that it may either increase or decrease the yield of secreted AChE, depending on the signal peptide. Surprisingly, the highest yield was obtained with the endogenous signal peptide. For all combinations, the yield was 2-3 times higher for Bungarus than for rat AChE, probably reflecting differences in the folding efficiency or stability of the polypeptides. The Michaelis constant (Km), the constant of inhibition by excess substrate (Kss) and the catalytic constant (kcat) values of the recombinant AChEs obtained both in P. pastoris and in COS cells, were essentially identical with those of the corresponding natural enzymes, and the Ki values of active-site and peripheral-site inhibitors (edrophonium, decamethonium, propidium) were similar.