The location and the significance of a cross-link between the sarcin/ricin domain of ribosomal RNA and the elongation factor-G.
The location and the significance of a cross-link between the sarcin/ricin domain of ribosomal RNA and the elongation factor-G.
复制标题
核糖体 RNA 的八叠球蛋白/蓖麻毒素结构域与延伸因子-G 之间的交联的位置和意义。
DOI：
10.1016/j.jmb.2004.01.020
复制
发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Wool,IraG
中科院分区：
文献类型：
--
作者：
Chan,Yuen-Ling;Correll,CarlC;Wool,IraG
在转位过程中，肽-tRNA从A-位移到P-位，mRNA在3‘方向被三个核苷酸取代。这个反应是由延伸因子-G(EF-G)催化的，并与核糖体依赖的GTP水解有关。易位的分子基础是核糖体功能中最重要的悬而未决的问题。一个可能为易位机制提供线索的关键问题是EF-G和核糖体成分之间接触的准确身份。为了进行鉴定，通过紫外线照射，EF-G与含有5-碘尿苷的sarcin/ricin结构域(SRD)寡核苷酸之间形成了共价键。通过质谱学和Edman降解，在EF-G中G结构域第127位的色氨酸与SRD中UAG2655U序列中的两个5-碘核苷酸中的任何一个之间建立了交联键。G2655是识别该因子核糖体结合位点的关键识别元件。交联键的位置提供了第一个直接证据，表明SRD非常接近EF-G催化中心。这表明SRD RNA在激活GTP水解过程中起着作用，从而导致因子的构象转变和从核糖体中释放。
During translocation peptidyl-tRNA moves from the A-site to the P-site and mRNA is displaced by three nucleotides in the 3′ direction. This reaction is catalyzed by elongation factor-G (EF-G) and is associated with ribosome-dependent hydrolysis of GTP. The molecular basis of translocation is the most important unsolved problem with respect to ribosome function. A critical question, one that might provide a clue to the mechanism of translocation, is the precise identity of the contacts between EF-G and ribosome components. To make the identification, a covalent bond was formed, by ultraviolet irradiation, between EF-G and a sarcin/ricin domain (SRD) oligoribonucleotide containing 5-iodouridine. The cross-link was established, by mass spectroscopy and by Edman degradation, to be between a tryptophan at position 127 in the G domain in EF-G and either one of two 5-iodouridine nucleotides in the sequence UAG2655U in the SRD. G2655 is a critical identity element for the recognition of the factor's ribosomal binding site. The site of the cross-link provides the first direct evidence that the SRD is in close proximity to the EF-G catalytic center. The proximity suggests that the SRD RNA has a role in the activation of GTP hydrolysis that leads to a transition in the conformation of the factor and to its release from the ribosome.