title: Crystal structure of the N-terminal segment of human eukaryotic translation initiation factor 2alpha.
abstract: Eukaryotic translation initiation factor 2alpha (eIF2alpha) is a member of the eIF2 heterotrimeric complex that binds and delivers Met-tRNA(i)(Met) to the 40 S ribosomal subunit in a GTP-dependent manner. Phosphorylation/dephosphorylation of eIF2alpha at Ser-51 is the major regulator of protein synthesis in eukaryotic cells. Here, we report the first structural analysis on eIF2, the three-dimensional structure of a 22-kDa N-terminal portion of human eIF2alpha by x-ray diffraction at 1.9 A resolution. This structure contains two major domains. The N terminus is a beta-barrel with five antiparallel beta-strands in an oligonucleotide binding domain (OB domain) fold. The phosphorylation site (Ser-51) is on the loop connecting beta3 and beta4 in the OB domain. A helical domain follows the OB domain, and the first helix has extensive interactions, including a disulfide bridge, to fix its orientation with respect to the OB domain. The two domains meet along a negatively charged groove with highly conserved residues, indicating a likely site for protein-protein interaction.
authors.affiliation: Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA.
authors.forename: M Cristina
authors.initials: MC
authors.lastname: Nonato
authors.forename: Joanne
authors.initials: J
authors.lastname: Widom
authors.forename: Jon
authors.initials: J
authors.lastname: Clardy
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004220:Disulfides; D015852:Eukaryotic Initiation Factor-2 / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D012358:RNA, Transfer, Met / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000378:metabolism; D014961:X-Ray Diffraction
chemical_list: D004220:Disulfides; D015852:Eukaryotic Initiation Factor-2; D012358:RNA, Transfer, Met; D012694:Serine