THE ATP HYDROLYSIS-DEPENDENT REACTION CYCLE OF THE ESCHERICHIA-COLI HSP70 SYSTEM - DNAK, DNAJ, AND GRPE
THE ATP HYDROLYSIS-DEPENDENT REACTION CYCLE OF THE ESCHERICHIA-COLI HSP70 SYSTEM - DNAK, DNAJ, AND GRPE
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DOI：
10.1073/pnas.91.22.10345
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发表时间：
1994-10-25
影响因子：
11.1
通讯作者：
HARTL, FU
中科院分区：
文献类型：
--
作者：
SZABO, A;LANGER, T;HARTL, FU
Hsp 70类分子伴侣结合未折叠的多肽链，并被认为参与许多蛋白质的细胞折叠途径。DnaK是大肠杆菌的Hsp 70蛋白，由伴侣蛋白DnaJ和辅因子GrpE调节。为了获得一个生物学相关的理解热休克蛋白70的作用机制，我们分析了一个模型反应，其中DnaK，DnaJ，和GrpE介导的折叠变性萤火虫荧光素酶。折叠底物蛋白的结合和释放涉及以下ATP水解依赖性循环：（i）未折叠的荧光素酶最初与DnaJ结合;（ii）在与DnaK-DnaJ相互作用后，DnaK水解其结合的ATP，导致形成稳定的DnaK-DnaK-DnaJ复合物;（iii）GrpE从DnaK释放ADP;和（iv）ATP与DnaK的结合触发底物蛋白的释放，从而完成反应循环。结合和释放的单个循环导致仅一部分荧光素酶分子的折叠。完全有效的折叠需要与DnaK和DnaJ的几轮ATP依赖性相互作用。
Molecular chaperones of the Hsp70 class bind unfolded polypeptide chains and are thought to be involved in the cellular folding pathway of many proteins. DnaK, the Hsp70 protein of Escherichia coli, is regulated by the chaperone protein DnaJ and the cofactor GrpE. To gain a biologically relevant understanding of the mechanism of Hsp70 action, we have analyzed a model reaction in which DnaK, DnaJ, and GrpE mediate the folding of denatured firefly luciferase. The binding and release of substrate protein for folding involves the following ATP hydrolysis-dependent cycle: (i) unfolded luciferase binds initially to DnaJ; (ii) upon interaction with luciferase-DnaJ, DnaK hydrolyzes its bound ATP, resulting in the formation of a stable luciferase-DnaK-DnaJ complex; (iii) GrpE releases ADP from DnaK; and (iv) ATP binding to DnaK triggers the release of substrate protein, thus completing the reaction cycle. A single cycle of binding and release leads to folding of only a fraction of luciferase molecules. Several rounds of ATP-dependent interaction with DnaK and DnaJ are required for fully efficient folding.