The Intrinsically Disordered N-terminal Extension of the ClpS Adaptor Reprograms Its Partner AAA+ ClpAP Protease.
The Intrinsically Disordered N-terminal Extension of the ClpS Adaptor Reprograms Its Partner AAA+ ClpAP Protease.
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DOI：
10.1016/j.jmb.2020.07.007
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发表时间：
2020-08-07
影响因子：
5.6
通讯作者：
Baker TA
中科院分区：
文献类型：
--
作者：
Torres-Delgado A;Kotamarthi HC;Sauer RT;Baker TA
衔接蛋白通过 AAA+ 蛋白酶调节底物选择。 ClpS 适配器将 N-degron 底物传递至 ClpAP，但抑制带有 ssrA 标签或其他相关degron 的底物的降解。 ClpS 如何抑制此类底物的降解尚不清楚。在这里，我们证明 ClpS 通过非竞争性机制阻碍对 ssrA 标记底物的识别，并且还减慢这些底物以及 N-降解决定子底物的后续解折叠/易位。这种机械活性的抑制很大程度上是 ClpS 抑制 ClpA 水解 ATP 的能力的结果，但一些证据表明 ClpS 对底物结合的抑制和其 ATP 酶抑制是可分离的活性。使用 ClpS 突变体和 ClpS-ClpA 嵌合体，我们确定 ClpA 与 ClpS 本质上无序的 N 末端延伸 (NTE) 的接合对于抑制 ClpAP 催化降解的多个步骤是必要且充分的。这些观察结果揭示了接头如何同时调节 AAA+ 酶的催化活性，有效促进某些底物的识别，抑制其他底物的识别，从而以特定方式影响其底物菜单的降解。我们建议其他适配器可能使用类似的机制来调节底物选择和分子机器的催化活性。
Adaptor proteins modulate substrate selection by AAA+ proteases. The ClpS adaptor delivers N-degron substrates to ClpAP but inhibits degradation of substrates bearing ssrA tags or other related degrons. How ClpS inhibits degradation of such substrates is poorly understood. Here, we demonstrate that ClpS impedes recognition of ssrA-tagged substrates by a non-competitive mechanism and also slows subsequent unfolding/translocation of these substrates as well as of N-degron substrates. This suppression of mechanical activity is largely a consequence of the ability of ClpS to repress ATP hydrolysis by ClpA, but several lines of evidence show that ClpS’s inhibition of substrate binding and its ATPase repression are separable activities. Using ClpS mutants and ClpS-ClpA chimeras, we establish that engagement of the intrinsically disordered N-terminal extension (NTE) of ClpS by ClpA is both necessary and sufficient to inhibit multiple steps of ClpAP-catalyzed degradation. These observations reveal how an adaptor can simultaneously modulate the catalytic activity of a AAA+ enzyme, efficiently promote recognition of some substrates, suppress recognition of other substrates and thereby affect degradation of its menu of substrates in a specific manner. We propose that similar mechanisms are likely to be used by other adaptors to regulate substrate choice and the catalytic activity of molecular machines.
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