TITLE

The stress response against denatured proteins in the deletion of cytosolic chaperones SSA1/2 is different from heat-shock response in Saccharomyces cerevisiae

AUTHOR(S)
Matsumoto, Rena; Akama, Kuniko; Rakwal, Randeep; Iwahashi, Hitoshi
PUB. DATE
January 2005
SOURCE
BMC Genomics;2005, Vol. 6, p1
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Background: A yeast strain lacking the two genes SSA1 and SSA2, which encode cytosolic molecular chaperones, acquires thermotolerance as well as the mild heat-shocked wild-type yeast strain. We investigated the genomic response at the level of mRNA expression to the deletion of SSA1/2 in comparison with the mild heat-shocked wild-type using cDNA microarray. Results: Yeast cDNA microarray analysis revealed that genes involved in the stress response, including molecular chaperones, were up-regulated in a similar manner in both the ssa1/2 deletion mutant and the mild heat-shocked wild-type. Genes involved in protein synthesis were upregulated in the ssa1/2 deletion mutant, but were markedly suppressed in the mild heat-shocked wild-type. The genes involved in ubiquitin-proteasome protein degradation were also up-regulated in the ssa1/2 deletion mutant, whereas the unfolded protein response (UPR) genes were highly expressed in the mild heat-shocked wild-type. RT-PCR confirmed that the genes regulating protein synthesis and cytosolic protein degradation were up-regulated in the ssa1/2 deletion mutant. At the translational level, more ubiquitinated proteins and proteasomes were detected in the ssa1/2 deletion mutant, than in the wild-type, confirming that ubiquitin-proteasome protein degradation was up-regulated by the deletion of SSA1/2. Conclusion: These results suggest that the mechanism for rescue of denatured proteins in the ssa1/2 deletion mutant is different from that in the mild heat-shocked wild-type: Activated protein synthesis in the ssa1/2 deletion mutant supplies a deficiency of proteins by their degradation, whereas mild heat-shock induces UPR.
ACCESSION #
28858563

 

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