Functional analysis of conserved cis- and trans-elements in the Hsp104 protein disaggregating machine
Functional analysis of conserved cis- and trans-elements in the Hsp104 protein disaggregating machine
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DOI：
10.1016/j.jsb.2012.05.007
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发表时间：
2012-08-01
影响因子：
3
通讯作者：
Lee, Sukyeong
中科院分区：
文献类型：
--
作者：
Biter, Amadeo B.;Lee, Jungsoon;Lee, Sukyeong
热休克蛋白104是一种形成双环状的AAA+ ATP酶，它利用ATP结合和水解的能量将蛋白质从先前的聚集状态中拯救出来。与其他AAA+机器一样，Hsp 104具有保守的顺式和反式作用元件，这是AAA+成员的标志，对Hsp 104功能至关重要。尽管有这些相似之处，但最近有人提出Hsp 104是一种非典型的AAA+ ATP酶，其在3D结构上与其他AAA+机器明显不同。因此，推测Hsp 104中的反式作用元件是位于非保守的M-结构域中的精氨酸，而不是预测的Arg-指残基。虽然结构上的差异已经得到解决，但Arg-指残基在Hsp 104中的作用仍存在争议。在这里，我们利用的能力，热休克蛋白104变体的突变在一个环保留ATP酶和分子伴侣的活动，阐明预测的Arg-指残基的功能作用。我们发现，进化上保守的Arg-指是绝对必要的ATP水解，但在Hsp 104的六聚体组装是不必要的。另一方面，M-结构域丝氨酸对于ATP水解不是严格必需的，并且以复杂的方式影响ATP酶和伴侣活性。我们的研究结果证实，热休克蛋白104是不是一个非典型的AAA+ ATP酶，并使用保守的结构元件常见的各种AAA+机器，以推动机械展开的聚集蛋白。(C)2012 Elsevier Inc. All rights reserved.
Hsp104 is a double ring-forming AAA+ ATPase, which harnesses the energy of ATP binding and hydrolysis to rescue proteins from a previously aggregated state. Like other AAA+ machines, Hsp104 features conserved cis- and trans-acting elements, which are hallmarks of AAA+ members and are essential to Hsp104 function. Despite these similarities, it was recently proposed that Hsp104 is an atypical AAA+ ATPase, which markedly differs in 3D structure from other AAA+ machines. Consequently, it was proposed that arginines found in the non-conserved M-domain, but not the predicted Arg-fingers, serve the role of the critical trans-acting element in Hsp104.While the structural discrepancy has been resolved, the role of the Arg-finger residues in Hsp104 remains controversial. Here, we exploited the ability of Hsp104 variants featuring mutations in one ring to retain ATPase and chaperone activities, to elucidate the functional role of the predicted Arg-finger residues. We found that the evolutionarily conserved Arg-fingers are absolutely essential for ATP hydrolysis but are dispensable for hexamer assembly in Hsp104. On the other hand, M-domain arginines are not strictly required for ATP hydrolysis and affect the ATPase and chaperone activities in a complex manner. Our results confirm that Hsp104 is not an atypical AAA+ ATPase, and uses conserved structural elements common to diverse AAA+ machines to drive the mechanical unfolding of aggregated proteins. (C) 2012 Elsevier Inc. All rights reserved.