Characterization of the yeast (1-->6)-beta-glucan biosynthetic components, Kre6p and Skn1p, and genetic interactions between the PKC1 pathway and extracellular matrix assembly.
A characterization of the S. cerevisiae KRE6 and SKN1 gene products extends previous genetic studies on their role in (1-->6)-beta-glucan biosynthesis (Roemer, T., and H. Bussey. 1991. 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. Proc. Natl. Acad. Sci. USA. 88:11295-11299; Roemer, T., S. Delaney, and H. Bussey. 1993. SKN1 and KRE6 define a pair of functional homologs encoding putative membrane proteins involved in beta-glucan synthesis. Mol. Cell. Biol. 13:4039-4048). KRE6 and SKN1 are predicted to encode homologous proteins that participate in assembly of the cell wall polymer (1-->6)-beta-glucan. KRE6 and SKN1 encode phosphorylated integral-membrane glycoproteins, with Kre6p likely localized within a Golgi subcompartment. Deletion of both these genes is shown to result in a dramatic disorganization of cell wall ultrastructure. Consistent with their direct role in the assembly of this polymer, both Kre6p and Skn1p possess COOH-terminal domains with significant sequence similarity to two recently identified glucan-binding proteins. Deletion of the yeast protein kinase C homolog, PKC1, leads to a lysis defect (Levin, D. E., and E. Bartlett-Heubusch. 1992. Mutants in the S. cerevisiae PKC1 gene display a cell cycle-specific osmotic stability defect. J. Cell Biol. 116:1221-1229). Kre6p when even mildly overproduced, can suppress this pkc1 lysis defect. When mutated, several KRE pathway genes and members of the PKC1-mediated MAP kinase pathway have synthetic lethal interactions as double mutants. These suppression and synthetic lethal interactions, as well as reduced beta-glucan and mannan levels in the pkc1 null wall, support a role for the PKC1 pathway functioning in cell wall assembly. PKC1 potentially participates in cell wall assembly by regulating the synthesis of cell wall components, including (1-->6)-beta-glucan.
Roemer
T
T
Biology Department, McGill University, Montreal, Quebec, Canada.
Paravicini
G
G
Payton
M A
MA
Bussey
H
H
D000595:Amino Acid Sequence; D001483:Base Sequence; D002473:Cell Wall / Q000378:metabolism / Q000648:ultrastructure; D005109:Extracellular Matrix / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005800:Genes, Fungal; D005936:Glucans / Q000096:biosynthesis*; D006056:Golgi Apparatus / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1; D008969:Molecular Sequence Data; D010641:Phenotype; D010766:Phosphorylation; D011493:Protein Kinase C / Q000235:genetics* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D047071:beta-Glucans
D005656:Fungal Proteins; D005936:Glucans; C081933:KRE6 protein, S cerevisiae; D008565:Membrane Proteins; C081932:SKN1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D047071:beta-Glucans; C064197:beta-1,6-glucan; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1