Mitochondrial Hsp78, a member of the Clp/Hsp100 family in Saccharomyces cerevisiae, cooperates with Hsp70 in protein refolding

FEBS Letters

Langer, Thomas¹  Liberek, Krzysztof²  Krzewska, Joanna² 

[1] Institut für Physiologische Chemie der Universität München, Goethestrasse 33, 80336 Munich, Germany;Department of Molecular and Cellular Biology, Faculty of Biotechnology, University of Gdansk, Kladki 24, 80-822 Gdansk, Poland

关键词: Chaperone;    Hsp100 family;    Protein refolding;    Mitochondrion;    Saccharomyces cerevisiae;    BSA;    bovine serum albumin;    PMSF;    phenylmethylsulfonyl fluoride;   

DOI  :  10.1016/S0014-5793(00)02423-6

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The molecular chaperone protein Hsp78, a member of the Clp/Hsp100 family localized in the mitochondria of Saccharomyces cerevisiae, is required for maintenance of mitochondrial functions under heat stress. To characterize the biochemical mechanisms of Hsp78 function, Hsp78 was purified to homogeneity and its role in the reactivation of chemically and heat-denatured substrate protein was analyzed in vitro. Hsp78 alone was not able to mediate reactivation of firefly luciferase. Rather, efficient refolding was dependent on the simultaneous presence of Hsp78 and the mitochondrial Hsp70 machinery, composed of Ssc1p/Mdj1p/Mge1p. Bacterial DnaK/DnaJ/GrpE, which cooperates with the Hsp78 homolog, ClpB in Escherichia coli, could not substitute for the mitochondrial Hsp70 system. However, efficient Hsp78-dependent refolding of luciferase was observed if DnaK was replaced by Ssc1p in these experiments, suggesting a specific functional interaction of both chaperone proteins. These findings establish the cooperation of Hsp78 with the Hsp70 machinery in the refolding of heat-inactivated proteins and demonstrate a conserved mode of action of ClpB homologs.

【 授权许可】

Unknown