Project description:Comparison of transcription profile of Pichia pastoris cells grown on Glucose medium with Pichia pastoris cells grown on Methanol/Glycerol medium, the fermentations were done in a chemostat.
Project description:Comparison of transcription profile of Pichia pastoris cells grown on Glucose medium with Pichia pastoris cells grown on Methanol/Glycerol medium, the fermentations were done in a chemostat. 2 color experiment in reference design. Pichia pastoris reference mix [mixed pool of Pichia pastoris cells sampled from various conditions including cells grown on glycerine, glucose and methanol, on full andminimal medium, in stationary and exponential growth phase, and in different stress states]
Project description:Pichia pastoris (Komagataella phaffi) transcription factor Mxr1p is known to regulate multiple metabolic pathways by binding to Mxr1p response elements of target genes. Mxr1p possesses a transactivation domain within the N-terminal 400 amino acids (Mxr1N400) which is functional during methanol metabolism. (Parua et al; 2012) Studies from our lab have shown that delta_mxr1 complemented with Mxr1N400 fails to reverse the growth defect of delta_mxr1 cultured in a medium containing methanol suggesting that region beyond N-terminal 400 amino acids has an essential function. We employed DNA microarray to identify genes whose expression is regulated by Mxr1N400 and full length Mxr1 during methanol metabolism. Pichia pastoris 14-3-3 regulates transcriptional activity of the methanol inducible transcription factor Mxr1 by direct interaction. Pabitra K. Parua, Paul M. Ryan and Elton T. Young. Molecular microbiology, 2012
Project description:Pichia pastoris is a widely used yeast platform for heterologous protein production. Although increasing gene dosage is a powerful strategy to improve recombinant protein production, an excess in the number of gene copies often leads to decreased product yields and increased metabolic burden. In order to find the bottlenecks of this strategy, here we present a transcriptome profile comparison of a series of Pichia pastoris strains carrying a different gene dosage of the Rhizopus oryzae lipase (Rol) as a model protein. Cells were grown on a mixture of glycerol:methanol in chemostat cultures. 2 color experiment in reference design.
Project description:The regulation of gene expression in Pichia pastoris has so far involved study of transcription factors. However, there are factors other than transcription factors affecting mRNA synthesis such as coactivators, enhancers, and chromatin modifiers. This study is a first ever report on epigenetic regulation in Pichia pastoris where, a histone acetyltransferase is reported to regulate transcription of genes involved in utilization of alternate carbon sources. We employed RNA Seq to identify new targets of Gcn5 in methanol medium.
Project description:The regulation of gene expression in Pichia pastoris has so far involved study of transcription factors. However, there are factors other than transcription factors affecting mRNA synthesis such as coactivators, enhancers, and chromatin modifiers. This study is a first ever report on epigenetic regulation in Pichia pastoris where, a histone acetyltransferase is reported to regulate transcription of genes involved in utilization of alternate carbon sources. We employed RNA Seq to identify new targets of Gcn5 in methanol medium.
Project description:Prevention of COVID-19 on a global scale will require the continued development of high-volume, low-cost platforms for the manufacturing of vaccines to supply on-going demand. Vaccine candidates based on recombinant protein subunits remain important because they can be manufactured at low costs in existing large-scale production facilities that use microbial hosts like Komagataella phaffii (Pichia pastoris). Here, we report an improved and scalable manufacturing approach for the SARS-CoV-2 spike protein receptor binding domain (RBD); this protein is a key antigen for several reported vaccine candidates. We genetically engineered a manufacturing strain of K. phaffii to obviate the requirement for methanol-induction of the recombinant gene. Methanol-free production improved the secreted titer of the RBD protein by >5x by alleviating protein folding stress. Removal of methanol from the production process enabled scale up to a 1,200 L pre-existing production facility. This engineered strain is now used to produce an RBD-based vaccine antigen that is currently in clinical trials and could be used to produce other variants of RBD as needed for future vaccines.
Project description:We investigated gene expression during the bench-scale batch fermentation phase, glycerol feed phase, glycerol-methanol mixture feed (GM) phase, and at different time points following methanol induction using RNA-Seq. We report that the addition of the GM phase may help to alleviate the adverse effects of methanol addition (alone) on P. pastoris cells. Secondly, enhanced upregulation of the mitogen-activated protein kinase (MAPK) signaling pathway was observed in P. pastoris following methanol induction. The MAPK signaling pathway may be related to P. pastoris cell growth, and may regulate the AOX1 promoter via regulatory factors activated by methanol-mediated stimulation. Thirdly, the unfolded protein response (UPR) and ER-associated degradation (ERAD) pathways were not significantly upregulated during the methanol induction period. These results imply that the presence of unfolded or misfolded phytase protein did not represent a serious problem in our study. Finally, the upregulation of the autophagy pathway during the methanol induction phase may be related to the degradation of damaged peroxisomes but not to the production of phytase. This work describes the metabolic characteristics of P. pastoris during heterologous protein production under high-cell-density fed-batch cultivation. We believe that the results of this study will aid further in-depth studies of P. pastoris protein expression, regulation, and secretory mechanisms.
Project description:We have identified a methanol- and biotin-starvation-inducible zinc finger protein named ROP [repressor of phosphoenolpyruvate carboxykinase (PEPCK)] in the methylotrophic yeast Pichia pastoris. When P.pastoris strain GS115 (wild-type, WT) is cultured in biotin-deficient, glucose ammonium (Bio-) medium, growth is suppressed due to the inhibition of anaplerotic synthesis of oxaloacetate, catalysed by the biotin-dependent enzyme pyruvate carboxylase (PC). Deletion of ROP results in a strain (∆ROP) that can grow under biotin-deficient conditions due to derepression of a biotin- and PC-independent pathway of anaplerotic synthesis of oxaloacetate. Northern analysis as well as microarray expression profiling of RNA isolated from WT and ∆ROP strains cultured in Bio(-) medium indicate that expression of the phosphoenolpyruvate carboxykinase gene (PEPCK) is induced in ∆ROP during biotin- or PC-deficiency even under glucose-abundant conditions. There is an excellent correlation between PEPCK expression and growth of ∆ROP in Bio(-) medium, suggesting that ROP-mediated regulation of PEPCK may have a crucial role in the biotin- and PC-independent growth of the ∆ROP strain. To our knowledge, ROP is the first example, of a zinc finger transcription factor involved in the catabolite repression of PEPCK in yeast cells cultured under biotin- or PC-deficient and glucose-abundant conditions. Agilent one-color experiment,Organism: Pichia pastoris ,Custom Pichia pastoris Gene Expression 8x15k array designed by Genotypic Technology Pvt. Ltd. (Agilent -AMADID: 25088 ) , Labeling kit: Agilent Quick-Amp labeling Kit (p/n5190-0442)