The ATPase cycle of the mitochondrial Hsp90 analog trap1
The ATPase cycle of the mitochondrial Hsp90 analog trap1
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DOI：
10.1074/jbc.m709516200
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发表时间：
2008-04-25
影响因子：
4.8
通讯作者：
Reinstein, Jochen
中科院分区：
文献类型：
--
作者：
Leskovar, Adriane;Wegele, Harald;Reinstein, Jochen
热休克蛋白90是一种ATP依赖的分子伴侣，其作用机制尚不清楚。在这里，我们提出了第一个ATP酶循环的Hsp 90家族的线粒体成员称为Trap 1（肿瘤坏死因子受体相关蛋白1）。使用生物化学，热力学和快速动力学方法，我们解剖的开放和封闭的构象之间的核苷酸调控重排的动力学。令人惊讶的是，在ATP结合后，Trap 1主要转变为闭合构象（70%），但与酵母的胞质Hsp 90不同，这个过程相当缓慢，为0.076 s（-1）。因为再打开（0.034 s（-1））比水解（k（hyd）= 0.0039 s（-1））快约10倍，水解是限速步骤，所以Trap 1不能使ATP水解。提出的ATP酶循环进一步审查的全球拟合程序，同时利用所有相关的实验数据。这一分析证实了我们的模型的两步结合机制的ATP，然后不可逆的ATP水解和一步产品（ADP）的释放。
Hsp90 is an ATP-dependent molecular chaperone whose mechanism is not yet understood in detail. Here, we present the first ATPase cycle for the mitochondrial member of the Hsp90 family called Trap1 (tumor necrosis factor receptor-associated protein 1). Using biochemical, thermodynamic, and rapid kinetic methods we dissected the kinetics of the nucleotide-regulated rearrangements between the open and the closed conformations. Surprisingly, upon ATP binding, Trap1 shifts predominantly to the closed conformation (70%), but, unlike cytosolic Hsp90 from yeast, this process is rather slow at 0.076 s(-1). Because reopening (0.034 s(-1)) is about ten times faster than hydrolysis (k(hyd) = 0.0039 s(-1)), which is the rate-limiting step, Trap1 is not able to commit ATP to hydrolysis. The proposed ATPase cycle was further scrutinized by a global fitting procedure that utilizes all relevant experimental data simultaneously. This analysis corroborates our model of a two-step binding mechanism of ATP followed by irreversible ATP hydrolysis and a one-step product ( ADP) release.