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PMID:15342786

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Citation

Youker, RT, Walsh, P, Beilharz, T, Lithgow, T and Brodsky, JL (2004) Distinct roles for the Hsp40 and Hsp90 molecular chaperones during cystic fibrosis transmembrane conductance regulator degradation in yeast. Mol. Biol. Cell 15:4787-97

Abstract

Aberrant secreted proteins can be destroyed by ER-associated protein degradation (ERAD), and a prominent, medically relevant ERAD substrate is the cystic fibrosis transmembrane conductance regulator (CFTR). To better define the chaperone requirements during CFTR maturation, the protein was expressed in yeast. Because Hsp70 function impacts CFTR biogenesis in yeast and mammals, we first sought ER-associated Hsp40 cochaperones involved in CFTR maturation. Ydj1p and Hlj1p enhanced Hsp70 ATP hydrolysis but CFTR degradation was slowed only in yeast mutated for both YDJ1 and HLJ1, suggesting functional redundancy. In contrast, CFTR degradation was accelerated in an Hsp90 mutant strain, suggesting that Hsp90 preserves CFTR in a folded state, and consistent with this hypothesis, Hsp90 maintained the solubility of an aggregation-prone domain (NBD1) in CFTR. Soluble ERAD substrate degradation was unaffected in the Hsp90 or the Ydj1p/Hlj1p mutants, and surprisingly CFTR degradation was unaffected in yeast mutated for Hsp90 cochaperones. These results indicate that Hsp90, but not the Hsp90 complex, maintains CFTR structural integrity, whereas Ydj1p/Hlj1p catalyze CFTR degradation.

Links

PubMed PMC524727 Online version:10.1091/mbc.E04-07-0584

Keywords

Amino Acid Sequence; Animals; Cystic Fibrosis Transmembrane Conductance Regulator/chemistry; Genetic Techniques; Genotype; HSP40 Heat-Shock Proteins; HSP90 Heat-Shock Proteins/chemistry; HSP90 Heat-Shock Proteins/physiology; Heat-Shock Proteins/chemistry; Heat-Shock Proteins/physiology; Humans; Hydrolysis; Microscopy, Fluorescence; Molecular Chaperones/metabolism; Molecular Sequence Data; Mutation; Protein Binding; Protein Folding; Protein Structure, Tertiary; Saccharomyces cerevisiae/metabolism; Time Factors

Significance

Annotations

Gene product Qualifier GO ID GO term name Evidence Code with/from Aspect Notes Status


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References

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