The location and the significance of a cross-link between the sarcin/ricin domain of ribosomal RNA and the elongation factor-G |
| |
Authors: | Chan Yuen-Ling Correll Carl C Wool Ira G |
| |
Affiliation: | Department of Biochemistry and Molecular Biology, The University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA. |
| |
Abstract: | 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. |
| |
Keywords: | elongation factor-G sarcin/ricin domain RNA G domain GTP hydrolysis translocation |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|