Dominant mutations in a gene encoding a putative protein kinase (BCK1) bypass the requirement for a Saccharomyces cerevisiae protein kinase C homolog.

The PKC1 gene of Saccharomyces cerevisiae encodes a homolog of mammalian protein kinase C that is required for yeast cell growth and division. To identify additional components of the pathway in which PKC1 functions, we isolated extragenic suppressors of a pkc1 deletion mutant. All of the suppressor mutations were dominant ...
for suppressor function and defined a single locus, which was designated BCK1 (for bypass of C kinase). A molecular clone of one suppressor allele, BCK1-20, was isolated on a centromere-containing plasmid through its ability to rescue a conditional pkc1 mutant. The BCK1 gene possesses a 4.4-kb uninterrupted open reading frame predicted to encode a 163-kDa protein kinase. The BCK1 gene product is not closely related to any known protein kinase, sharing only 45% amino acid identity with its closest known relative (the STE11-encoded protein kinase) through a region restricted to its putative C-terminal catalytic domain. Deletion of BCK1 resulted in a temperature-sensitive cell lysis defect, which was suppressed by osmotic stabilizing agents. Because pkc1 mutants also display a cell lysis defect, we suggest that PKC1 and BCK1 may normally function within the same pathway. Suppressor alleles of BCK1 differed from the wild-type gene in a region surrounding a potential PKC phosphorylation site immediately upstream of the predicted catalytic domain. This region may serve as a hinge between domains whose interaction is regulated by PKC1.
Mesh Terms:
Amino Acid Sequence, Base Sequence, Chromosome Mapping, DNA, Fungal, Fungal Proteins, Genes, Dominant, Genes, Fungal, Genes, Suppressor, Mitogen-Activated Protein Kinase Kinases, Molecular Sequence Data, Osmolar Concentration, Protein Kinase C, Protein Kinases, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Sequence Alignment, Temperature
Mol. Cell. Biol.
Date: Jan. 01, 1992
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