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Ssa1p chaperone interacts with the guanine nucleotide exchange factor of ras Cdc25p and controls the cAMP pathway in Saccharomyces cerevisiae
Author(s) -
Geymonat Marco,
Wang Lili,
Garreau Hervé,
Jacquet Michel
Publication year - 1998
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1998.01118.x
Subject(s) - biology , guanine nucleotide exchange factor , saccharomyces cerevisiae , cdc25 , immunoprecipitation , nucleotide , guanine , gene , chaperone (clinical) , yeast , biochemistry , microbiology and biotechnology , signal transduction , cyclin dependent kinase 1 , medicine , pathology , cell cycle
We have found that the guanine nucleotide exchange factor for ras, Cdc25p, interacts with Ssa1p in Saccharomyces cerevisiae . This interaction was observed with GST‐fused Cdc25p polypeptides and confirmed by co‐immunoprecipitation with the endogenous Cdc25p. Hsp82 appeared also to be co‐immunoprecipitated with Cdc25p, albeit to a lower level than Hsp70. In a strain deleted for SSA1 and SSA2 , we observed a reduced cellular content of Cdc25p. Consistent with a reduced activity of the cAMP‐dependent PKA pathway, the rate of accumulation of both trehalose and glycogen was stimulated in the ssa ‐deleted strain. Expression of SSA1 reversed these effects, whereas co‐expression of SSA1 and PDE2 restored high accumulation. The expression of genes repressed by cAMP, GAC1 and TPS1 , fused to β‐galactosidase, was also stimulated by deletion of SSA genes. The effect of ssa deletion on glycogen accumulation was lost in a strain deleted for CDC25 rescued by the RAS2 ile152 allele. Altogether, these results lead to the conclusion that Ssa1p positively controls the cAMP pathway through Cdc25p. We propose that this connection plays a critical role in the adaptation of cells to stress conditions.