title: X-ray structure of translation initiation factor eIF2gamma: implications for tRNA and eIF2alpha binding.
abstract: The x-ray structure of the gamma-subunit of the heterotrimeric translation initiation factor eIF2 has been determined to 2.4-A resolution. eIF2 is a GTPase that delivers the initiator Met-tRNA to the P site on the small ribosomal subunit during a rate-limiting initiation step in translation. The structure of eIF2gamma closely resembles that of EF1A.GTP, consisting of an N-terminal G domain followed by two beta-barrels arranged in a closed configuration with domain II packed against the G domain in the vicinity of the Switch regions. The G domain of eIF2gamma has an unusual zinc ribbon motif, not previously found in other GTPases. Structure-based site-directed mutagenesis was used to identify two adjacent features on the surface of eIF2gamma that bind the alpha-subunit and Met-tRNA(i)(Met), respectively. These structural, biochemical, and genetic results provide new insights into eIF2 ternary complex assembly.
authors.affiliation: Laboratories of Molecular Biophysics, The Rockefeller University, New York, New York 10021, USA.
authors.forename: Antonina
authors.initials: A
authors.lastname: Roll-Mecak
authors.forename: Pankaj
authors.initials: P
authors.lastname: Alone
authors.forename: Chune
authors.initials: C
authors.lastname: Cao
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Dever
authors.forename: Stephen K
authors.initials: SK
authors.lastname: Burley
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001105:Archaea; D018360:Crystallography, X-Ray; D015852:Eukaryotic Initiation Factor-2 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017017:Methanococcus / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D012343:RNA, Transfer / Q000378:metabolism*; D012358:RNA, Transfer, Met / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D015852:Eukaryotic Initiation Factor-2; D012358:RNA, Transfer, Met; D012343:RNA, Transfer