The A730 loop is an important component of the active site of the VS ribozyme
The A730 loop is an important component of the active site of the VS ribozyme
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DOI：
10.1006/jmbi.2001.4996
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发表时间：
2001-09-28
影响因子：
5.6
通讯作者：
Lilley, DMJ
中科院分区：
文献类型：
--
作者：
Lafontaine, DA;Wilson, TJ;Lilley, DMJ
VS核酶的核心由五个螺旋组成，它们在茎环底物上以顺式或反式方式催化位点特异性切割。2-3-4螺旋结的结构表明，在螺旋II和螺旋VI之间形成了一个裂缝，可能作为底物的受体。序列变异的详细分析表明，螺旋II和螺旋VI的基部凸起起了结构作用。相比之下，A730环中核苷酸的同一性对核酶的活性非常重要。A756的碱基特别重要，任何其他核苷酸的取代或碱基的消蚀都会导致切割速率的大幅降低。然而，A756的变体有效地结合底物，并且在全局折叠中没有缺陷。这些结果表明A730环是核酶活性位点的重要组成部分，而A756可能在催化过程中起关键作用。(C) 2001学术出版社。
The core of the VS ribozyme comprises five helices, that act either in cis or in trans on a stem-loop substrate to catalyse site-specific cleavage. The structure of the 2-3-6 helical junction indicates that a cleft is formed between helices II and VI that is likely to serve as a receptor for the substrate. Detailed analysis of sequence variants suggests that the base bulges of helices II and VI play an architectural role. By contrast, the identity of the nucleotides in the A730 loop is very important for ribozyme activity. The base of A756 is particularly vital, and substitution by any other nucleotide or ablation of the base leads to a major reduction in cleavage rate. However, variants of A756 bind substrate efficiently, and are not defective in global folding. These results suggest that the A730 loop is an important component of the active site of the ribozyme, and that A756 could play a kev role in catalysis. (C) 2001 Academic Press.