Mitochondrial Hsp78, a member of the Clp/Hsp100 family in Saccharomyces cerevisiae, cooperates with Hsp70 in protein refolding
Mitochondrial Hsp78, a member of the Clp/Hsp100 family in Saccharomyces cerevisiae, cooperates with Hsp70 in protein refolding
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DOI：
10.1016/s0014-5793(00)02423-6
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发表时间：
2001-01-26
期刊：
影响因子：
3.5
通讯作者：
Liberek, K
中科院分区：
文献类型：
--
作者：
Krzewska, J;Langer, T;Liberek, K
分子伴侣蛋白Hsp78是位于酿酒酵母线粒体中的C1P/Hsp100家族成员，在热应激条件下维持线粒体的功能是必需的。为了研究Hsp78功能的生化机制，对Hsp78进行了纯化，并在体外分析了Hsp78在化学和热变性底物蛋白再激活中的作用。单独的HSP78不能介导萤火虫荧光素酶的重新激活。相反，有效的复性依赖于Hsp78和线粒体Hsp70机制的同时存在，线粒体Hsp70机制由Ssc1p/Mdj1p/Mge1p组成。细菌DNAK/DNAJ/GRPE与大肠杆菌中的Hsp78同源物C1pB协同作用，不能替代线粒体Hsp70系统。然而，在这些实验中，如果用Ssc1p取代DNAK，则可以观察到依赖于Hsp78的荧光素酶的有效复性，这表明这两种伴侣蛋白存在特定的功能相互作用。这些发现建立了Hsp78与Hsp70机制在热灭活蛋白的重折叠中的合作，并证明了C1pB同源物的保守作用模式。(C)2001年欧洲生化学会联合会。爱思唯尔科学公司出版。版权所有。
The molecular chaperone protein Hsp78, a member of the C1p/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, C1pB 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 C1pB homologs. (C) 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.