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PMID: 11927566 Published · ppublish English Journal Article

The large subunit of initiation factor aIF2 is a close structural homologue of elongation factors.

The EMBO journal ·Vol. 21 ·No. 7 ·2002-04-02 ·Pages 1821-32

Schmitt E, Blanquet S, Mechulam Y

Abstract

The heterotrimeric factor e/aIF2 plays a central role in eukaryotic/archaeal initiation of translation. By delivering the initiator methionyl-tRNA to the ribosome, e/aIF2 ensures specificity of initiation codon selection. The three subunits of aIF2 from the hyperthermophilic archaeon Pyrococcus abyssi could be overproduced in Escherichia coli. The beta and gamma subunits each contain a tightly bound zinc. The large gamma subunit is shown to form the structural core for trimer assembly. The crystal structures of aIF2gamma, free or complexed to GDP-Mg(2+) or GDPNP-Mg(2+), were resolved at resolutions better than 2 A. aIF2gamma displays marked similarities to elongation factors. A distinctive feature of e/aIF2gamma is a subdomain containing a zinc-binding knuckle. Examination of the nucleotide-complexed aIF2gamma structures suggests mechanisms of action and tRNA binding properties similar to those of an elongation factor. Implications for the mechanism of translation initiation in both eukarya and archaea are discussed. In particular, positioning of the initiator tRNA in the ribosomal A site during the search for the initiation codon is envisaged.

MeSH Terms
Amino Acid Sequence Animals Eukaryotic Initiation Factor-2/chemistry,genetics,metabolism,physiology Guanine Nucleotides/metabolism Models, Molecular Molecular Sequence Data Protein Structure, Tertiary Pyrococcus/chemistry Sequence Homology, Amino Acid
Chemicals
Eukaryotic Initiation Factor-2 Guanine Nucleotides
Authors & Affiliations
3 authors, click to expand affiliations / ORCID
Schmitt Emmanuelle
Laboratoire de Biochimie, Unité Mixte de Recherche 7654, CNRS-Ecole Polytechnique, F-91128 Palaiseau cedex, France. emma@botrytis.polytechnique.fr
Blanquet Sylvain
Mechulam Yves
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Article Info
Journal
The EMBO journal
Abbr.
EMBO J
ISSN
0261-4189
DOI
10.1093/emboj/21.7.1821
Email
emma@botrytis.polytechnique.fr
Published
2002-04-02
Pages
1821-32
Language
English
Region
England
NLM ID
8208664
PMCID
PMC125960
Subset
IM
External Links
PubMed source DOI: 10.1093/emboj/21.7.1821 PMC Full Text View journal details
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