Journal Article

Yeast beta-glucan synthesis: KRE6 encodes a predicted type II membrane protein required for glucan synthesis in vivo and for glucan synthase activity in vitro

Bussey H, Roemer T

1991

Overview

The KRE6 gene product is required for synthesis of the major beta-glucans of the yeast cell wall, as mutations in this gene confer reduced levels of both the (1 leads to 6)- and (1 leads to 3)-beta-D-glucan polymers. Cloning and sequencing of KRE6 reveals a gene encoding a predicted 80-kDa protein with a central transmembrane domain and the topology of a type II membrane protein. Null mutants of KRE6 grow slowly, have larger cells, and show a reduction in alkali-insoluble wall glucans. The mutants show good viability and are not osmotically sensitive, but they are more susceptible to beta-glucanase digestion and mechanical stress than wild-type cells. The specific activity of the GTP-dependent, membrane-associated, in vitro (1 leads to 3)-beta-glucan synthase is reduced 50% in kre6 null mutants, and this reduction correlates with the mutation in meiotic tetrads. Transformants of kre6 null mutants with a KRE6 gene expressed from a centomere-based vector show a 4- to 5-fold increase in vitro (1 leads to 3)-beta-glucan synthase activity over transformants with the vector alone. The phenotype and structure of the KRE6 product, Kre6p, suggest that Kre6p may be a beta-glucan synthase, and if so, it implies that beta-glucan synthases are functionally redundant in yeast. Alternatively, Kre6p may be part of a single multiprotein glucan synthase or modulate its activity. Use of KRE6 should permit a genetic analysis of eukaryotic (1 leads to 3)-beta-glucan synthesis.

• Publisher: National Academy of Sciences of the United States of America,National Acad Sciences
• Subject: activity / Alleles / Amino Acid Sequence / amino acid sequences / beta -glucan / beta-glucans / Biological and medical sciences / biosintesis / biosynthese / biosynthesis / Cell Membrane / Cell Membrane - enzymology / Cell walls / Chromosome Deletion / Cloning, Molecular / code genetique / codigo genetico / Diploidy / enzymology / Fundamental and applied biological sciences. Psychology / gene products / genes / Genes, Fungal / genetic code / genetica / genetics / genetique / Genomic Library / glucan synthase / glucane / glucano / Glucans / Glucans - biosynthesis / Glucosyltransferases / Glucosyltransferases - genetics / Glucosyltransferases - metabolism / KRE6 gene / levadura / levure / liasas / lyase / lyases / membrana / membrane / Membrane Proteins / membranes / metabolism / Molecular and cellular biology / Molecular genetics / Molecular Sequence Data / Mutagenesis, Insertional / mutant / mutantes / mutants / nucleotide sequence / Phenotypes / Plasmids / Polymers / predictions / proteinas / proteine / Proteins / Restriction Mapping / Saccharomyces cerevisiae / Saccharomyces cerevisiae - enzymology / Saccharomyces cerevisiae - genetics / Schizosaccharomyces pombe Proteins / synthesis / Yeasts