Expression of foreign enzymes in yeast is a traditional genetic engineering approach; however, useful secretory enzymes are not produced in every case. The hyperthermostable a-amylase encoded by the AmyL gene of Bacillus licheniformis was expressed in Saccharomyces cerevisiae; however, it was only weakly produced and was degraded by the proteasome. To determine the cause of low a-amylase production, AmyL was expressed in a panel of yeast mutants harboring knockouts in non-essential genes. Elevated AmyL production was observed in 44 mutants. The knockout genes were classified into six functional categories. Remarkably, all non-essential genes required for N-linked oligosaccharide synthesis and a gene encoding an oligosaccharyl transferase subunit were identified. Immunoblotting demonstrated that differently underglycosylated forms of AmyL were secreted from oligosaccharide synthesis-deficient mutants, while a fully glycosylated form was produced by wild-type yeast, suggesting that N-linked glycosylation of AmyL inhibited its secretion in yeast. Mutational analysis of six potential N-glycosylation sites in AmyL revealed that the N33Q and N309Q mutations remarkably affected AmyL production. To achieve higher AmyL production in yeast, all six N-glycosylation sites of AmyL were mutated. In wild-type yeast, production of the resulting non-glycosylated form of AmyL was threefold higher than that of the glycosylated form.
|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|