The GANC Tetraloop: A Novel Motif in the Group IIC Intron Structure
The GANC Tetraloop: A Novel Motif in the Group IIC Intron Structure
复制标题
DOI：
10.1016/j.jmb.2008.08.043
复制
发表时间：
2008-11-14
影响因子：
5.6
通讯作者：
Pyle, Anna Marie
中科院分区：
文献类型：
--
作者：
Keating, Kevin S.;Toor, Navtej;Pyle, Anna Marie
四环是RNA三级结构的常见组成部分，大多数四环属于三种特征明确的类别之一：GNRA，UNCG和CUYG。在这里，我们提出的序列和结构的第四个高度保守类的四环，只发生在zeta-zeta'的相互作用组IIC内含子。通过内含子RNA序列比对的系统发育分析，在IIC组内含子的晶体结构中，沿着一种不寻常的同源受体，鉴定了这种GANC四环。与通过广泛的氢键相互作用稳定的常规四环-受体相互作用不同，GANC-受体相互作用限于四环的保守腺苷和受体的单个嘌呤之间的单个碱基堆叠，其由一到三个核苷酸凸起组成，并且不包含A平台。与GNRA四环不同，GANC四环相对于相邻的螺旋形成锐角，向螺旋的主槽侧弯曲约45度。这些结构属性允许GANC四环精确地适合IIC组内含子核心，从而证明结构基序可以适应特定生态位中的功能。(C)2008爱思唯尔有限公司保留所有权利。
Tetraloops are a common building block for RNA tertiary structure, and most tetraloops fall into one of three well-characterized classes: GNRA, UNCG, and CUYG. Here, we present the sequence and structure of a fourth highly conserved class of tetraloop that occurs only within the zeta-zeta' interaction of group IIC introns. This GANC tetraloop was identified, along with an unusual cognate receptor, in the crystal structure of the group IIC intron and through phylogenetic analysis of intron RNA sequence alignments. Unlike conventional tetraloop-receptor interactions, which are stabilized by extensive hydrogen-bonding interactions, the GANC-receptor interaction is limited to a single base stack between the conserved adenosine of the tetraloop and a single purine of the receptor, which consists of a one- to three-nucleotide bulge and does not contain an A-platform. Unlike GNRA tetraloops, the GANC tetraloop forms a sharp angle relative to the adjacent helix, bending by approximately 45 degrees toward the major groove side of the helix. These structural attributes allow GANC tetraloops to fit precisely within the group IIC intron core, thereby demonstrating that structural motifs can adapt to function in a specific niche. (C) 2008 Elsevier Ltd. All rights reserved.