Original Articles

Molecular and General Genetics MGG

, Volume 242, Issue 6, pp 631-640

Genetic interactions among genes involved in the STT4-PKC1 pathway of Saccharomyces cerevisiae

  • Satoshi YoshidaAffiliated withDepartment of Biology, Faculty of Science, University of Tokyo
  • , Yoshikazu OhyaAffiliated withDepartment of Biology, Faculty of Science, University of TokyoDepartment of Genetics, Stanford University School of Medicine
  • , Akihiko NakanoAffiliated withDepartment of Biology, Faculty of Science, University of Tokyo
  • , Yasuhiro AnrakuAffiliated withDepartment of Biology, Faculty of Science, University of Tokyo

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Abstract

Loss of yeast protein kinase C function results in three distinct phenotypes: staurosporine sensitivity, cell lysis and blockage of cell cycle progression at the G2/M boundary. Genetic analysis of the PKC1/STT1 protein kinase C gene and its interactions with STT4, encoding an upstream phosphatidylinositol 4-kinase, and BCK1, encoding a downstream protein kinase, reveal that they form part of a single pathway. However, the BCK1-20 mutation (a gain-of-function mutation of BCK1) or overexpression of PKC1 cannot suppress all of the phenotypes caused by the loss of STT4 function, strongly suggesting the existence of a branch point between STT4 and PKC1. We also describe the MSS4 gene, a multicopy suppressor of the temperature-sensitive stt4-1 mutation. MSS4 is predicted to encode a hydrophilic protein of 779 amino acid residues and is essential for cell growth. Based on genetic and biochemical data, we suggest that MSS4 acts downstream of STT4, but in a pathway that does not involve PKC1.

Key words

Staurosporine Phosphatidylinositol 4-kinase Protein kinase C Cell lysis Cell cycle