2dcu | pdb_00002dcu
Crystal structure of translation initiation factor aIF2betagamma heterodimer with GDP
Structural highlights
Function[IF2G_PYRFU] eIF-2 functions in the early steps of protein synthesis by forming a ternary complex with GTP and initiator tRNA (By similarity). [IF2B_PYRFU] eIF-2 functions in the early steps of protein synthesis by forming a ternary complex with GTP and initiator tRNA (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedArchaeal/eukaryotic initiation factor 2 (a/eIF2) consists of alpha-, beta-, and gamma-subunits and delivers initiator methionine tRNA (Met-tRNA(i)) to a small ribosomal subunit in a GTP-dependent manner. The structures of the aIF2betagamma (archaeal initiation factor 2 betagamma) heterodimeric complex in the apo and GDP forms were analyzed at 2.8- and 3.4-A resolution, respectively. The results showed that the N-terminal helix and the central helix-turn-helix domain of the beta-subunit bind to the G domain of the gamma-subunit but are distant from domains 2 and 3, to which the alpha-subunit and Met-tRNA(i) bind. This result is consistent with most of the previous analyses of eukaryotic factors, and thus indicates that the binding mode is essentially conserved among a/eIF2. Comparison with the uncomplexed structure showed significant differences between the two forms of the beta-subunit, particularly the C-terminal zinc-binding domain, which does not interact with the gamma-subunit and was suggested previously to be involved in GTP hydrolysis. Furthermore, the switch 1 region in the gamma-subunit, which is shown to be responsible for Met-tRNA(i) binding by mutational analysis, is moved away from the nucleotide through the interaction with highly conserved R87 in the beta-subunit. These results implicate that conformational change of the beta-subunit facilitates GTP hydrolysis by inducing the conformational change of the switch 1 region toward the off state. Structure of archaeal translational initiation factor 2 betagamma-GDP reveals significant conformational change of the beta-subunit and switch 1 region.,Sokabe M, Yao M, Sakai N, Toya S, Tanaka I Proc Natl Acad Sci U S A. 2006 Aug 29;103(35):13016-21. Epub 2006 Aug 21. PMID:16924118[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References | ||||||||||||||||||||||
