Overexpression of yeast Hsp110 homolog Sse1p suppresses ydj1-151 thermosensitivity and restores Hsp90-dependent activity.

The Saccharomyces cerevisiae heat-shock protein (Hsp)40, Ydj1p, is involved in a variety of cellular activities that control polypeptide fate, such as folding and translocation across intracellular membranes. To elucidate the mechanism of Ydj1p action, and to identify functional partners, we screened for multicopy suppressors of the temperature-sensitive ydj1-151 mutant and ...
identified a yeast Hsp110, SSE1. Overexpression of Sse1p also suppressed the folding defect of v-Src kinase in the ydj1-151 mutant and partially reversed the alpha-factor translocation defect. SSE1-dependent suppression of ydj1-151 thermosensitivity required the wild-type ATP-binding domain of Sse1p. However, the Sse1p mutants maintained heat-denatured firefly luciferase in a folding-competent state in vitro and restored human androgen receptor folding in sse1 mutant cells. Because the folding of both v-Src kinase and human androgen receptor in yeast requires the Hsp90 complex, these data suggest that Ydj1p and Sse1p are interacting cochaperones in the Hsp90 complex and facilitate Hsp90-dependent activity.
Mesh Terms:
Adenosine Triphosphate, Amino Acid Sequence, Binding Sites, Genes, Fungal, HSP110 Heat-Shock Proteins, HSP40 Heat-Shock Proteins, HSP70 Heat-Shock Proteins, HSP90 Heat-Shock Proteins, Heat-Shock Proteins, Humans, Luciferases, Molecular Sequence Data, Mutation, Protein Binding, Protein Denaturation, Protein Folding, Protein Structure, Tertiary, Receptors, Androgen, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Sequence Alignment, Temperature
Mol. Biol. Cell
Date: Aug. 01, 2002
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