RNA aptamers to the adenosine moiety of S-adenosyl methionine: structural inferences from variations on a theme and the reproducibility of SELEX
RNA aptamers to the adenosine moiety of S-adenosyl methionine: structural inferences from variations on a theme and the reproducibility of SELEX
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DOI：
10.1093/nar/25.10.2020
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发表时间：
1997-05-15
影响因子：
14.9
通讯作者：
Gold, L
中科院分区：
文献类型：
--
作者：
Burke, DH;Gold, L
我们利用体外筛选（指数富集的配体系统进化技术，SELEX）来分离针对S - 腺苷甲硫氨酸（SAM）的RNA“适配体”。单个适配体序列符合先前在针对三磷酸腺苷（ATP）和烟酰胺腺嘌呤二核苷酸（NAD⁺）的适配体筛选中所注意到的腺苷结合的结构元件。当我们将65个腺苷结合序列之间的序列保守模式与已发表的腺苷适配体结构进行比较时，我们发现保守性最高的核苷酸直接与结合的腺苷接触，并且结合口袋外的一个保守核苷酸处于能够稳定结合口袋内核苷酸的位置。从其结合模式来看，适配体结合多种含腺苷辅因子的能力很容易理解，这种结合模式使5'位置暴露于溶剂中。我们提出，那些在远离反应部分结合其靶标的适配体可能特别适合用于催化。最后，我们估计每10¹¹个序列中可能有一个能够形成这种结构基序，并且可能还有许多其他腺苷结合基序由于在起始随机库中的比例较低而未被检测到。
We used in vitro selection (SELEX) to isolate RNA 'aptamers' to S-adenosyl methionine (SAM). Individual aptamer sequences conform to the structural element noted previously for adenosine binding in selections for aptamers to ATP and NAD(+). When we compare the patterns of sequence conservation among 65 adenosine-binding sequences to the published structure of the adenosine aptamer, we find that the most highly conserved nucleotides contact the bound adenosine directly, and that one conserved nucleotide outside the binding pocket is in position to stabilize;nucleotides within the binding pocket. The aptamer's ability to bind diverse adenosine-containing cofactors is easily understood in terms of its mode of binding, which leaves the 5' position exposed to solvent. We propose that aptamers that bind their targets away from the reactive moiety may be particularly well suited for catalysis. Finally, we estimate that one sequence in 10(11) may be able to form this structural motif, and that there may be many other adenosine-binding motifs that have escaped detection because of their lower representation in the starting random pools.