RsgA couples the maturation state of the 30S ribosomal decoding center to activation of its GTPase pocket.
RsgA couples the maturation state of the 30S ribosomal decoding center to activation of its GTPase pocket.
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DOI：
10.1093/nar/gkx324
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发表时间：
2017-06-20
影响因子：
14.9
通讯作者：
Connell SR
中科院分区：
文献类型：
--
作者：
López-Alonso JP;Kaminishi T;Kikuchi T;Hirata Y;Iturrioz I;Dhimole N;Schedlbauer A;Hase Y;Goto S;Kurita D;Muto A;Zhou S;Naoe C;Mills DJ;Gil-Carton D;Takemoto C;Himeno H;Fucini P;Connell SR
在30s核糖体亚基的生物发生过程中，组装因子被认为可以防止低自由能的错误折叠中间状态的积累，这些中间状态慢慢转化为成熟的30s亚基，即动力学捕获的粒子。在组装因素中，环状排列的GTP酶RsgA在30S解码中心的成熟过程中起着至关重要的作用。本文采用定向羟基自由基探针法和单粒子冷冻-EM法研究了RsgA΄S的作用机理。我们的结果表明，RsgA破坏了30S结构的稳定，包括晚期结合的R-蛋白，为避免动力学捕获的组装中间体提供了结构基础。此外，RsgA利用其独特的GTP酶口袋和与30S的特定相互作用来协调GTP酶的激活和30S亚基的成熟状态。这种协调验证了解码中心的架构，并有助于RsgA的及时释放，以控制30s生物发生的进展。
During 30S ribosomal subunit biogenesis, assembly factors are believed to prevent accumulation of misfolded intermediate states of low free energy that slowly convert into mature 30S subunits, namely, kinetically trapped particles. Among the assembly factors, the circularly permuted GTPase, RsgA, plays a crucial role in the maturation of the 30S decoding center. Here, directed hydroxyl radical probing and single particle cryo-EM are employed to elucidate RsgA΄s mechanism of action. Our results show that RsgA destabilizes the 30S structure, including late binding r-proteins, providing a structural basis for avoiding kinetically trapped assembly intermediates. Moreover, RsgA exploits its distinct GTPase pocket and specific interactions with the 30S to coordinate GTPase activation with the maturation state of the 30S subunit. This coordination validates the architecture of the decoding center and facilitates the timely release of RsgA to control the progression of 30S biogenesis.