Conformational Activation of Argonaute by Distinct yet Coordinated Actions of the Hsp70 and Hsp90 Chaperone Systems
Conformational Activation of Argonaute by Distinct yet Coordinated Actions of the Hsp70 and Hsp90 Chaperone Systems
复制标题
Hsp70 和 Hsp90 伴侣系统独特但协调的作用对 Argonaute 的构象激活
DOI：
10.1016/j.molcel.2018.04.010
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发表时间：
2018
期刊：
影响因子：
16
通讯作者：
Tomari Y
中科院分区：
文献类型：
--
作者：
Tsuboyama K;Tadakuma H;Tomari Y
将小 RNA 加载到 Argonaute（RNA 沉默的核心蛋白）中需要 Hsp70/Hsp90 分子伴侣机制。这种机制还激活许多其他客户，包括类固醇激素受体和激酶，但它们的结构在伴侣依赖性激活过程中如何变化仍不清楚。在这里，我们利用单分子福斯特共振能量转移（smFRET）来探测伴侣机制介导的果蝇Ago2的构象变化。我们发现空的Ago2以各种闭合构象存在。 Hsp70 系统（Hsp40 和 Hsp70）和 Hsp90 系统（Hop、Hsp90 和 p23）共同使 Ago2 成为开放的活性形式。 Hsp70 系统（但不是单独的 Hsp90 系统）足以使 Ago2 部分填充开放形式。相反，Hsp90 系统需要延长 Ago2 在打开状态下的停留时间，而 Ago2 必须由 Hsp70 系统瞬时启动。我们的数据揭示了伴侣机制的独特且协调的作用，其中 Hsp70 系统扩展了 Ago2 的结构整体，而 Hsp90 系统捕获并稳定了活性形式。
Loading of small RNAs into Argonaute, the core protein in RNA silencing, requires the Hsp70/Hsp90 chaperone machinery. This machinery also activates many other clients, including steroid hormone receptors and kinases, but how their structures change during chaperone-dependent activation remains unclear. Here, we utilized single-molecule Förster resonance energy transfer (smFRET) to probe the conformational changes ofDrosophilaAgo2 mediated by the chaperone machinery. We found that empty Ago2 exists in various closed conformations. The Hsp70 system (Hsp40 and Hsp70) and the Hsp90 system (Hop, Hsp90, and p23) together render Ago2 into an open, active form. The Hsp70 system, but not the Hsp90 system alone, is sufficient for Ago2 to partially populate the open form. Instead, the Hsp90 system is required to extend the dwell time of Ago2 in the open state, which must be transiently primed by the Hsp70 system. Our data uncover distinct and coordinated actions of the chaperone machinery, where the Hsp70 system expands the structural ensembles of Ago2 and the Hsp90 system captures and stabilizes the active form.