Induced fit of RNA on binding the L7Ae protein to the kink-turn motif
Induced fit of RNA on binding the L7Ae protein to the kink-turn motif
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DOI：
10.1261/rna.2680605
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发表时间：
2005-08-01
期刊：
影响因子：
4.5
通讯作者：
Lilley, DMJ
中科院分区：
文献类型：
--
作者：
Turner, B;Melcher, SE;Lilley, DMJ
扭结-转折是RNA中广泛存在的基序，由三个核苷酸组成，两侧是连续的A-G错配。重要的例子在核糖体、U4RNA和参与RNA修饰的snoRNAs中发现。该基序是一个常见的蛋白质结合部位，RNA在晶体结构中采用紧密扭结的构象。然而，在自由溶液中，扭结构象和伸展构象之间存在着动态的交换，金属离子的加入使平衡朝着扭结形式发展。在这里，我们使用荧光共振能量转移(FRET)来证明，即使在没有金属离子的情况下，黄褐古迹的L7Ae蛋白也能以纳摩尔亲和力与含有扭转角的RNA结合，并诱导折叠成紧密扭结的构象。因此，这种RNA在RNA折叠过程中可能充当一个相对灵活的铰链，直到通过L7或相关蛋白质的结合固定到其最终的扭曲结构中。
The kink-turn is a widespread motif in RNA consisting of a three-nucleotide bulge flanked on one side by consecutive A-G mismatches. Important examples are found in the ribosome, U4 RNA, and in snoRNAs involved in RNA modification. The motif is a common protein binding site, and the RNA has been found to adopt a tightly kinked conformation in crystal structures. However, in free solution there is a dynamic exchange between kinked and extended conformations, with the equilibrium driven toward the kinked form by the addition of metal ions. Here we used fluorescence resonance energy transfer (FRET) to show that the L7Ae protein of Archaeoglobus fulgidus binds to RNA containing a kink-turn with nanomolar affinity, and induces folding into the tightly kinked conformation even in the absence of metal ions. Thus this RNA may act as a relatively flexible hinge during RNA folding, until fixed into its ultimate kinked structure by the binding of L7 or related protein.