2D74

Crystal structure of translation initiation factor aIF2betagamma heterodimer

Summary for 2D74

• Entry DOI: 10.2210/pdb2d74/pdb
• Descriptor: Translation initiation factor 2 gamma subunit, Translation initiation factor 2 beta subunit, ZINC ION, ... (4 entities in total)
• Functional Keywords: protein complex, translation
• Biological source: Pyrococcus furiosus; More
• Total number of polymer chains: 2
• Total formula weight: 63692.36

Authors

Sokabe, M.,Yao, M.,Sakai, N.,Toya, S.,Tanaka, I. (deposition date: 2005-11-16, release date: 2006-07-25, Last modification date: 2024-10-30)

Primary citation

Sokabe, M.,Yao, M.,Sakai, N.,Toya, S.,Tanaka, I.
Structure of archaeal translational initiation factor 2 betagamma-GDP reveals significant conformational change of the beta-subunit and switch 1 region.
Proc.Natl.Acad.Sci.USA, 103:13016-13021, 2006

PubMed Abstract: Archaeal/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.

PubMed: 16924118
DOI: 10.1073/pnas.0604165103

Experimental method

X-RAY DIFFRACTION (2.8 Å)