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首页> 外文期刊>Journal of Molecular Biology >The 1.3 A crystal structure of a biotin-binding pseudoknot and the basis for RNA molecular recognition.
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The 1.3 A crystal structure of a biotin-binding pseudoknot and the basis for RNA molecular recognition.

机译：1.3生物素结合假结的晶体结构和RNA分子识别的基础。

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摘要

A pseudoknot-containing aptamer isolated from a pool of random sequence molecules has been shown previously to represent an optimal RNA solution to the problem of binding biotin. The affinity of this RNA molecule is nonetheless orders of magnitude weaker than that of its highly evolved protein analogs, avidin and streptavidin. To understand the structural basis for biotin binding and to compare directly strategies for ligand recognition available to proteins and RNA molecules, we have determined the 1.3 A crystal structure of the aptamer complexed with its ligand. Biotin is bound at the interface between the pseudoknot's stacked helices in a pocket defined almost entirely by base-paired nucleotides. In comparison to the protein avidin, the aptamer packs more tightly around the biotin headgroup and makes fewer contacts with its fatty acid tail. Whereas biotin is deeply buried within the hydrophobic core in the avidin complex, the aptamer relies on a combination of hydrated magnesium ions and immobilized water molecules to surround its ligand. In addition to demonstrating fundamentally different approaches to molecular recognition by proteins and RNA, the structure provides general insight into the mechanisms by which RNA function is mediated by divalent metals. Copyright 2000 Academic Press.
机译：从随机序列分子库中分离出来的含假结的适体以前已被证明代表了一种结合生物素问题的最佳RNA解决方案。然而，该RNA分子的亲和力比其高度进化的蛋白质类似物亲和素和链霉亲和素的亲和力弱几个数量级。为了了解生物素结合的结构基础，并直接比较蛋白质和RNA分子可用的配体识别策略，我们确定了与配体复合的适体的1.3 A晶体结构。生物素结合在假结的堆叠螺旋之间的界面上，该螺旋几乎完全由碱基配对的核苷酸定义。与蛋白抗生物素蛋白相比，适体在生物素头基周围更紧密地堆积，并且与其脂肪酸尾部的接触更少。生物素深深地被埋在抗生物素蛋白复合物的疏水核中，而适体则依赖于水合镁离子和固定化水分子的结合以围绕其配体。除了演示从根本上不同的蛋白质和RNA分子识别方法外，该结构还提供了对二价金属介导RNA功能的机制的一般认识。版权所有2000学术出版社。

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