Characterisation of the KRE2 gene in Saccharomyces cerevisiae

• Main Author: Hill, Kathryn
• Format: Others
• Language: en
• Published: McGill University 1990
• Subjects: Saccharomyces cerevisiae > Genetics.
• Online Access: http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=60075

The kre2-1 mutation is one of a number of K1 killer resistant complementation groups in Saccharomyces cerevisiae. kre2-1 cells bind less K1 killer toxin than wild type cells due to a reduced affinity for the toxin molecule and yet contain wild type levels of (1$ to$6)-$ beta$-D-glucan, a component of the toxin receptor molecule. The KRE2 gene was cloned by complementation of the kre2-1 mutation and is predicted to encode a 433 amino acid protein directed into the secretory pathway. Haploid strains which carried a disruption at the KRE2 locus, grew more slowly than wild type cells, and showed a defect in the N-linked glycosylation of secreted proteins analysed. Genetic and protein analyses showed the defect to be in the assembly of the core oligosaccharide, most likely in the attachment of one or perhaps two mannose residues to the core structure. The mutant core in kre2 cells appeared to be a less efficient substrate for outer chain elaboration. === A plausible interpretation of these results is that those mannose residues added to the core oligosaccharide in a KRE2 dependent manner are involved in the cross-linking of (1$ to$6)-$ beta$-D-glucan to mannoprotein in the cell wall to complete the K1 killer toxin receptor and failure to make such attachments is the basis of resistance to toxin in kre2 cells.