title: The yeast Hsp110 family member, Sse1, is an Hsp90 cochaperone.
abstract: In eukaryotes, production of the diverse repertoire of molecular chaperones during normal growth and in response to stress is governed by the heat shock transcription factor HSF. The HSC82 and HSP82 genes, encoding isoforms of the yeast Hsp90 molecular chaperone, were recently identified as targets of the HSF carboxyl-terminal activation domain (CTA), whose expression is required for cell cycle progression during prolonged heat stress conditions. In the present study, we have identified additional target genes of the HSF CTA, which include nearly all of the heat shock-inducible members of the Hsp90 chaperone complex, demonstrating coordinate regulation of these components by HSF. Heat shock induction of SSE1, encoding a member of the Hsp110 family of heat shock proteins, was also dependent on the HSF CTA. Disruption of SSE1 along with STI1, encoding an established subunit of the Hsp90 chaperone complex, resulted in a severe synthetic growth phenotype. Sse1 associated with partially purified Hsp90 complexes and deletion of the SSE1 gene rendered cells susceptible to the Hsp90 inhibitors macbecin and geldanamycin, suggesting functional interaction between Sse1 and Hsp90. Sse1 is required for function of the glucocorticoid receptor, a model substrate of the Hsp90 chaperone machinery, and Hsp90-based repression of HSF under nonstress conditions. Taken together, these data establish Sse1 as an integral new component of the Hsp90 chaperone complex in yeast.
authors.affiliation: Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109-0606, USA.
authors.forename: X D
authors.initials: XD
authors.lastname: Liu
authors.forename: K A
authors.initials: KA
authors.lastname: Morano
authors.forename: D J
authors.initials: DJ
authors.lastname: Thiele
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D016227:Benzoquinones; D050957:HSP110 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D047029:Lactams, Macrocyclic; D011809:Quinones / Q000494:pharmacology; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D000903:Antibiotics, Antineoplastic; D016227:Benzoquinones; D050957:HSP110 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D011809:Quinones; C494656:SSE1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C025514:macbecin I; C025515:macbecin II; C001277:geldanamycin