Divalent ions tune the kinetics of a bacterial GTPase center rRNA folding transition from secondary to tertiary structure.
Divalent ions tune the kinetics of a bacterial GTPase center rRNA folding transition from secondary to tertiary structure.
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DOI：
10.1261/rna.068361.118
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发表时间：
2018-12
期刊：
影响因子：
--
通讯作者：
Hall KB
中科院分区：
文献类型：
--
作者：
Welty R;Pabit SA;Katz AM;Calvey GD;Pollack L;Hall KB
RNA从二级结构到三级结构的折叠通常取决于用于有效静电电荷屏蔽（非特异性缔合）或结合（特异性缔合）的二价离子。为了测量不同的二价阳离子如何改变60个核苷酸的E. coli rRNA GT3折叠中心，结合Mg ~（2+）、Ca ~（2+）或Sr ~（2+）存在下的停流荧光和Mg ~（2+）存在下的时间分辨小角X射线散射（SAXS）观察折叠过程。在加入每个二价离子后，RNA立即经历从具有二级结构的延伸状态到更紧凑结构的转变。随后，特定的二价离子调制人口的中间体构象合奏沿着折叠途径的过渡时间长于10毫秒。五个折叠转变的速率常数作用于从亚毫秒到几十秒的时间尺度。RNA三级结构对二价阳离子身份的敏感性影响了RNA折叠中除最快事件外的所有事件，并使我们能够确定那些偏好Mg 2+的状态。GTdR中心RNA似乎已经优化了其折叠轨迹，以特异性地利用这种最丰富的细胞内二价离子。
Folding of an RNA from secondary to tertiary structure often depends on divalent ions for efficient electrostatic charge screening (nonspecific association) or binding (specific association). To measure how different divalent cations modify folding kinetics of the 60 nucleotide E. coli rRNA GTPase center, we combined stopped-flow fluorescence in the presence of Mg2+, Ca2+, or Sr2+ together with time-resolved small angle X-ray scattering (SAXS) in the presence of Mg2+ to observe the folding process. Immediately upon addition of each divalent ion, the RNA undergoes a transition from an extended state with secondary structure to a more compact structure. Subsequently, specific divalent ions modulate populations of intermediates in conformational ensembles along the folding pathway with transition times longer than 10 msec. Rate constants for the five folding transitions act on timescales from submillisecond to tens of seconds. The sensitivity of RNA tertiary structure to divalent cation identity affects all but the fastest events in RNA folding, and allowed us to identify those states that prefer Mg2+. The GTPase center RNA appears to have optimized its folding trajectory to specifically utilize this most abundant intracellular divalent ion.
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影响因子：
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作者：
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通讯作者：
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DOI：
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期刊：
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