Protein mannosyltransferases (PMTs) catalyze the O-mannosylation of serine and threonine residues of proteins in the endoplasmic reticulum. The five PMT genes coding for protein mannosyltransferases, designated as PMT1, 2, 4, 5 and 6, were identified from Pichia pastoris genome based on the homology to PMT genes in Saccharomyces cerevisiae genome, which has seven PMT genes. The homologues of S. cerevisiae PMT 3 &7 genes are absent in P. pastoris genome. Approximately 5% of the recombinant insulin precursor expressed in P. pastoris is O-mannosylated. In this study, we attempted to prevent O-mannosylation of insulin precursor in vivo, through inactivation of the Pichia PMT genes. Since multiple PMTs are found to be expressed, it was important to understand which of these are involved in O-mannosylation of the insulin precursor. The genes encoding PMT1, 4, 5 and 6 were knocked out by insertional inactivation method. Inactivation of PMT genes 4, 5 and 6 showed approximately 16-28% reductions in the O-mannosylation of insulin precursor. The PMT1 gene disrupted Pichia clone showed approximately 60% decrease in O-mannosylated insulin precursor, establishing its role as an important enzyme for insulin precursor O-mannosylation.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|