Project description:Adaptation to alkalinization of the medium in fungi involves an extensive remodeling of gene expression. Komagataella phaffii is an ascomycetous yeast that has become an organism widely used for heterologous protein expression. We explore here the transcriptional impact of moderate alkalinization in this yeast. In spite of a minor effect on growth, shifting the cultures from pH 5.5 to 8.0 or 8.2 provokes significant changes in the mRNA levels of over 700 genes. Functional categories such as arginine and methionine biosynthesis, non-reductive iron uptake and phosphate metabolism are enriched in induced genes, whereas many genes encoding iron-sulfur proteins or members of the respirasome were repressed. We also show that alkalinization is accompanied by oxidative stress and we propose this circumstance as a common trigger of a subset of the observed changes. PHO89, encoding a Na+/Pi cotransporter, appears among the most potently induced genes by high pH. We demonstrate that this response is mainly based on two calcineurin-dependent response elements located in its promoter, thus indicating that alkalinization triggers a calcium-mediated signal in K. phaffii. Further characterization of alkaline pH responsive promoters may lead to developing novel pH-controlled systems for heterologous protein expression in this fungus.
Project description:Komagataella phaffii, also known as Pichia pastoris, is a common host for the production of biologics and enzymes, due to fast growth, high productivity, and advancements in host engineering. Several K. phaffii variants are commonly used as interchangeable base strains, which confounds efforts to improve this host. In this study, genomic and transcriptomic analyses of Y-11430 (CBS7435), X-33, GS115, and eight other variants enabled a comparative assessment of the relative fitness of these hosts for recombinant protein expression. Cell wall integrity explained the majority of the variation among strains, impacting transformation efficiency, growth, methanol metabolism, and secretion of heterologous proteins. Y-11430 exhibited the highest activity of genes involved in methanol utilization, up to two-fold higher transcription of heterologous genes, and robust growth. With a more permeable cell wall, X-33 displayed a six-fold higher transformation efficiency and up to 1.2-fold higher titers than Y-11430. X-33 also shared nearly all mutations, and a defective variant of HIS4, with GS115, precluding robust growth. Transferring two beneficial mutations identified in X-33 into Y-11430 resulted in an optimized base strain that provided up to four-fold higher transformation efficiency and three-fold higher protein titers, while retaining robust growth. The approach employed here to assess unique banked variants in a species and then transfer key beneficial variants into a base strain should also facilitate rational assessment of a broad set of other recombinant hosts.
Project description:Komagataella phaffii, also known as Pichia pastoris, is a common host for the production of biologics and enzymes, due to fast growth, high productivity, and advancements in host engineering. Several K. phaffii variants are commonly used as interchangeable base strains, which confounds efforts to improve this host. In this study, genomic and transcriptomic analyses of Y-11430 (CBS7435), X-33, GS115, and eight other variants enabled a comparative assessment of the relative fitness of these hosts for recombinant protein expression. Cell wall integrity explained the majority of the variation among strains, impacting transformation efficiency, growth, methanol metabolism, and secretion of heterologous proteins. Y-11430 exhibited the highest activity of genes involved in methanol utilization, up to two-fold higher transcription of heterologous genes, and robust growth. With a more permeable cell wall, X-33 displayed a six-fold higher transformation efficiency and up to 1.2-fold higher titers than Y-11430. X-33 also shared nearly all mutations, and a defective variant of HIS4, with GS115, precluding robust growth. Transferring two beneficial mutations identified in X-33 into Y-11430 resulted in an optimized base strain that provided up to four-fold higher transformation efficiency and three-fold higher protein titers, while retaining robust growth. The approach employed here to assess unique banked variants in a species and then transfer key beneficial variants into a base strain should also facilitate rational assessment of a broad set of other recombinant hosts.
Project description:In order to investigate the specific mechanism of maltose on the production of recombinant type III collagen by Komagataella phaffii GS115, Two groups were set up, control group C using BMMY medium and experimental group M using BMMY + 1% maltose.
2025-02-01 | GSE225749 | GEO
Project description:QTL analysis of protein secretion in Komagataella phaffii
Project description:We analyzed the chromatin accessibility and nucleosome positioning by ATAC-seq of both null and transgene-expressing strains of Komagataella phaffii (Pichia pastoris) under different growth conditions. These data enabled identification of the features that determine performance of various integration sites for transgene expression. Understanding chromatin accessibility and nucleosome positioning can provide further clarity into gene regulation and expression broadly in this organism.
Project description:Recombinant TLP (rTLP) and CHI (rCHI), expressed by Komagataella phaffii, were used as as haze-protein models, for having similar characteristics (aggregation potential, melting point, functionality, glycosylation levels and bentonite adsorption) to the native-haze proteins from Vitis vinifera.
Project description:Non-conventional methylotrophic yeast Komagataella phaffii is an important production host in biotechnology and an emerging model organism. In this work, we studied K. phaffii response to nitrogen starvation during cultivation in media with methanol as the sole carbon source. The results were compared with well-established model yeast Saccharomyces cerevisiae. Some of the observed effects of nitrogen starvation in K. phaffii were similar to those in S. cerevisiae, despite this yeast does not have metabolic pathway for methanol utilization. The effects include activation of autophagy, transport and catabolism of nitrogen-containing compounds, interconversions of amino acids, and biosynthesis of fatty acids. K. phaffii cells also demonstrated specific response to nitrogen starvation including suppression of genes involved in methanol metabolism and other peroxisomal processes and activation of purine catabolism genes.