Molecular recognition of cAMP by an RNA aptamer
Molecular recognition of cAMP by an RNA aptamer
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DOI：
10.1021/bi000149n
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发表时间：
2000-08-01
期刊：
影响因子：
2.9
通讯作者：
Breaker, RR
中科院分区：
文献类型：
--
作者：
Koizumi, M;Breaker, RR
使用体外选择从随机序列库中分离出两类结合第二信使腺苷3 '，5'-环一磷酸（cAMP; I）的RNA适体。I类和II类适体分别由33个和31个核苷酸的RNA形成，并且各自由相似的茎环和单链结构元件组成。II类适体占最终选择的RNA群体的主导地位，其需要二价阳离子以形成复合物，并显示出与10 μ M相似的cAMP解离常数（KD）。代表性的II类适体显示出对5 ′-和3 ′-磷酸化核苷如ATP、5 ′-AMP和3 ′-AMP的显著区分。然而，cAMP的组分如腺嘌呤和腺苷也被结合，表明腺嘌呤部分是配体结合的主要正决定因素。cAMP结合的特异性似乎是通过与腺嘌呤碱基的氢键相互作用以及与核糖部分上的基团的空间相互作用来建立的。此外，适体识别8，5 '-O-环腺苷（2），但不识别N-3，5'-环腺苷（3），表明该RNA可能选择性识别cAMP的N-糖苷键的反构象。
TWO classes of RNA aptamers that bind the second messenger adenosine 3',5'-cyclic monophosphate (cAMP; I) were isolated from a random-sequence pool using in vitro selection. Class I and class II aptamers are formed by 33- and 31-nucleotide RNAs, respectively, and each is comprised of similar stem-loop and single-stranded structural elements. Class II aptamers, which dominate the final selected RNA population, require divalent cations for complex formation and display a dissociation constant (KD) for cAMP of similar to 10 mu M A representative class II aptamer exhibits substantial discrimination against 5'- and 3'-phosphorylated nucleosides such as ATP, 5'-AMP, and 3'-AMP. However, components of cAMP such as adenine and adenosine also are bound, indicating that the adenine moiety is the primary positive determinant of ligand binding. Specificity of cAMP binding appears to be established by hydrogen bonding interactions with the adenine base as well as by steric interactions with groups on the ribose moiety. In addition, the aptamer recognizes 8,5'-O-cycloadenosine (2) but not N-3,5'-cycloadenosine (3), indicating that this RNA might selectively recognize the anti conformation of the N-glycosidic bond of cAMP.