Conserved conformational changes in the ATPase cycle of human Hsp90
Conserved conformational changes in the ATPase cycle of human Hsp90
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DOI：
10.1074/jbc.m800540200
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发表时间：
2008-06-27
影响因子：
4.8
通讯作者：
Buchner, Johannes
中科院分区：
文献类型：
--
作者：
Richter, Klaus;Soroka, Joanna;Buchner, Johannes
二聚体分子伴侣 Hsp90 是数百种底物蛋白激活和稳定所必需的，其中许多底物蛋白参与信号转导途径。激活过程取决于 Hsp90 对 ATP 的水解。 Hsp90 由 C 端二聚化结构域、可与底物蛋白相互作用的中间结构域和 N 端 ATP 结合结构域组成。酵母 Hsp90 的 ATP 酶循环提出了一个复杂的构象变化循环，其中反应过程中的一个关键步骤需要两个原聚体的瞬时 N 端二聚化。人类 Hsp90 的 ATP 酶循环尚不清楚，并且在关键机制方面提出了显着差异。人 Hsp90 α 和 Hsp90 β 的 ATP 水解速度比酵母 Hsp90 慢 10 倍。尽管存在这些差异，我们的实验表明潜在的酶机制非常相似。在这两种情况下，涉及两个亚基 N 端结构域的协同构象重排控制着 ATP 周转率，而 N 端串扰决定了限速步骤。此外，与酵母 Hsp90 类似，通过添加来自人类或酵母来源的辅助伴侣 Aha1，可以将人类 Hsp90 的缓慢 ATP 水解刺激高达 100 倍以上。总之，我们的结果表明，Hsp90 ATPase 反应的基本原理在酵母和人类之间是保守的，包括 N 末端结构域的二聚化及其通过将 ATP 盖从其原始位置重新定位到具有催化能力的位置来进行调节。
The dimeric molecular chaperone Hsp90 is required for the activation and stabilization of hundreds of substrate proteins, many of which participate in signal transduction pathways. The activation process depends on the hydrolysis of ATP by Hsp90. Hsp90 consists of a C-terminal dimerization domain, a middle domain, which may interact with substrate protein, and an N-terminal ATP-binding domain. A complex cycle of conformational changes has been proposed for the ATPase cycle of yeast Hsp90, where a critical step during the reaction requires the transient N-terminal dimerization of the two protomers. The ATPase cycle of human Hsp90 is less well understood, and significant differences have been proposed regarding key mechanistic aspects. ATP hydrolysis by human Hsp90 alpha and Hsp90 beta is 10-fold slower than that of yeast Hsp90. Despite these differences, our experiments suggest that the underlying enzymatic mechanisms are highly similar. In both cases, a concerted conformational rearrangement involving the N-terminal domains of both subunits is controlling the rate of ATP turnover, and N-terminal cross-talk determines the rate-limiting steps. Furthermore, similar to yeast Hsp90, the slow ATP hydrolysis by human Hsp90s can be stimulated up to over 100-fold by the addition of the co-chaperone Aha1 from either human or yeast origin. Together, our results show that the basic principles of the Hsp90 ATPase reaction are conserved between yeast and humans, including the dimerization of the N-terminal domains and its regulation by the repositioning of the ATP lid from its original position to a catalytically competent one.