title: PKR and GCN2 kinases and guanine nucleotide exchange factor eukaryotic translation initiation factor 2B (eIF2B) recognize overlapping surfaces on eIF2alpha.
abstract: Four stress-responsive protein kinases, including GCN2 and PKR, phosphorylate eukaryotic translation initiation factor 2alpha (eIF2alpha) on Ser51 to regulate general and gene-specific protein synthesis. Phosphorylated eIF2 is an inhibitor of its guanine nucleotide exchange factor, eIF2B. Mutations that block translational regulation were isolated throughout the N-terminal OB-fold domain in Saccharomyces cerevisiae eIF2alpha, including those at residues flanking Ser51 and around 20 A away in the conserved motif K79GYID83. Any mutation at Glu49 or Asp83 blocked translational regulation; however, only a subset of these mutations impaired Ser51 phosphorylation. Substitution of Ala for Asp83 eliminated phosphorylation by GCN2 and PKR both in vivo and in vitro, establishing the critical contributions of remote residues to kinase-substrate recognition. In contrast, mutations that blocked translational regulation but not Ser51 phosphorylation impaired the binding of eIF2B to phosphorylated eIF2alpha. Thus, two structurally distinct effectors of eIF2 function, eIF2alpha kinases and eIF2B, have evolved to recognize the same surface and overlapping determinants on eIF2alpha.
authors.affiliation: National Institutes of Health, 6 Center Dr., Bethesda, MD 20892-2427, USA.
authors.forename: Madhusudan
authors.initials: M
authors.lastname: Dey
authors.forename: Bruce
authors.initials: B
authors.lastname: Trieselmann
authors.forename: Emily G
authors.initials: EG
authors.lastname: Locke
authors.forename: Jingfang
authors.initials: J
authors.lastname: Lu
authors.forename: Chune
authors.initials: C
authors.lastname: Cao
authors.forename: Arvin C
authors.initials: AC
authors.lastname: Dar
authors.forename: Thanuja
authors.initials: T
authors.lastname: Krishnamoorthy
authors.forename: Jinsheng
authors.initials: J
authors.lastname: Dong
authors.forename: Frank
authors.initials: F
authors.lastname: Sicheri
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Dever
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D017124:Conserved Sequence; D004252:DNA Mutational Analysis; D015852:Eukaryotic Initiation Factor-2 / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D020717:Eukaryotic Initiation Factor-2B / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010442:Peptide Chain Initiation, Translational / Q000235:genetics* / Q000502:physiology; D010766:Phosphorylation; D011487:Protein Conformation; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000502:physiology*; D012694:Serine / Q000235:genetics / Q000378:metabolism; D019892:eIF-2 Kinase / Q000235:genetics / Q000378:metabolism / Q000502:physiology*
chemical_list: D015852:Eukaryotic Initiation Factor-2; D020717:Eukaryotic Initiation Factor-2B; D029701:Saccharomyces cerevisiae Proteins; D012694:Serine; D011494:Protein Kinases; C512912:GCN2 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D019892:eIF-2 Kinase