Isolation and nucleotide sequence of a Saccharomyces cerevisiae protein kinase gene suppressing the cell cycle start mutation cdc25.
We have isolated two unlinked yeast genes complementing the cell division cycle mutant cdc25-1, one containing the wild type allele CDC25 and the other acting as an extragenic suppressor of the cdc25-1 lesion if present on a multicopy plasmid. Nucleotide sequence analysis of the suppressor gene has revealed an open reading frame that encodes a 45,000-dalton protein belonging to the protein kinase family. The cdc25-suppressing protein kinase (PK-25) shows 48% sequence similarity to the catalytic subunit (CA) of mammalian cAMP-dependent protein kinase and 27-31% similarity to cyclic nucleotide-independent enzymes, including the yeast CDC28 gene product. The PK-25 gene was targeted by integrative transformation into a chromosomal region unlinked to the CYR2 site, the structural gene of CA. The cdc25-suppressing protein kinase is also functionally different from CA, since cyr2 strains deficient in the free catalytic subunit remain temperature sensitive if transformed with a multicopy plasmid containing the PK-25 gene. Furthermore, a deficiency of the cAMP-binding regulatory subunit (RA) caused by the bcy1 mutation fails to suppress the cdc25 mutation, indicating that PK-25 does not interact with the cAMP receptor protein. Our data suggest that the cdc25 suppressor gene encodes a cAMP-independent protein kinase involved in the control of the cell cycle start.
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002453:Cell Cycle; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000032:analysis* / Q000302:isolation & purification; D046911:Macromolecular Substances; D009154:Mutation; D011494:Protein Kinases / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D013696:Temperature
D004271:DNA, Fungal; D046911:Macromolecular Substances; D011494:Protein Kinases