PKC1, a protein kinase C homologue of Saccharomyces cerevisiae, participates in microtubule function through the yeast EB1 homologue, BIM1.

Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, Japan 739-8527.
BACKGROUND: RSC is a chromatin-remodelling complex of Saccharomyces cerevisiae and essential for growth. Its catalytic subunit is encoded by the NPS1/STH1 gene. At the present time, little is known regarding the cellular function of RSC. RESULTS: To identify genes with functions related to NPS1, we screened high-copy suppressor genes for the temperature- and thiabendazole (TBZ)-sensitive mutant allele of NPS1, nps1-105. Amongst the suppressors we cloned PKC1/STT1 and BIM1 that encoded a homologue of mammalian protein kinase C and a conserved microtubule binding protein homologous to human EB1, respectively. Both the temperature sensitive mutation of PKC1, stt1, and the bim1 null mutation caused synthetic growth defects with nps1-105. A genetic analysis of the functional relationships between these genes revealed that PKC1 suppressed the defect of nps1-105 through the BIM1 function but not by the activation of the MPK1/MAPK pathway. The stt1 mutation alone showed TBZ sensitivity and delayed the G2-phase progression at semi-permissive temperatures. Both of these stt1 phenotypes were suppressed by the over-expression of BIM1. In addition, stt1 as well as nps1-105, mis-segregated a mini-chromosome at frequencies higher than the wild-type at a permissive temperature. The mis-segregation was enhanced in the nps1-105 stt1 double mutant. CONCLUSION: These results suggest that Pkc1p plays a role which is relevant to microtubule functions and that this role is mediated by a hitherto unknown PKC signalling pathway and by Bim1p
Mesh Terms:
Blotting, Northern, Blotting, Western, Cell Cycle Proteins, Cells, Cultured, Chromosome Segregation, DNA Primers, Fluorescent Antibody Technique, Fungal Proteins, Gene Dosage, Microtubule Proteins, Microtubules, Polymerase Chain Reaction, Protein Kinase C, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Signal Transduction, Thiabendazole
Genes Cells Sep. 01, 2001; 6(9);775-88 [PUBMED:11554924]
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