Structural Analysis of Human Argonaute-2 Bound to a Modified siRNA Guide
Structural Analysis of Human Argonaute-2 Bound to a Modified siRNA Guide
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DOI：
10.1021/jacs.6b04454
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发表时间：
2016-07-20
影响因子：
15
通讯作者：
MacRae, Ian J.
中科院分区：
文献类型：
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作者：
Schirle, Nicole T.;Kinberger, Garth A.;MacRae, Ian J.
将化学修饰并入小干扰RNA（siRNA）中增加了它们的代谢稳定性并改善了它们的组织分布。然而，这些修饰如何影响与Argonaute-2（Ago 2）（siRNA的分子靶点）的相互作用尚不清楚。在此，我们提出了与含有广泛骨架修饰的代谢稳定的siRNA结合的人Ago 2的晶体结构。与等效的未修饰的siRNA复合物的结构的比较表明，Ago 2的结构相对不受结合的siRNA中的化学修饰的影响。相比之下，相对于未修饰的siRNA，修饰的siRNA似乎更具可塑性和位移，以优化与Ago 2的接触。结构-活性分析揭示，即使在siRNA种子区的3'半中的主要构象扰动对敲低效力也具有相对适度的影响。这些发现为siRNA中耐受的各种修饰模式提供了解释，并为推进治疗性siRNA设计提供了结构基础。
Incorporation of chemical modifications into small interfering RNAs (siRNAs) increases their metabolic stability and improves their tissue distribution. However, how these modifications impact interactions with Argonaute-2 (Ago2), the molecular target of siRNAs, is not known. Herein we present the crystal structure of human Ago2 bound to a metabolically stable siRNA containing extensive backbone modifications. Comparison to the structure of an equivalent unmodified-siRNA complex indicates that the structure of Ago2 is relatively unaffected by chemical modifications in the bound siRNA. In contrast, the modified siRNA appears to be much more plastic and shifts, relative to the unmodified siRNA, to optimize contacts with Ago2. Structure-activity analysis reveals that even major conformational perturbations in the 3' half of the siRNA seed region have a relatively modest effect on knockdown potency. These findings provide an explanation for a variety of modification patterns tolerated in siRNAs and a structural basis for advancing therapeutic siRNA design.