title: Domains of eIF1A that mediate binding to eIF2, eIF3 and eIF5B and promote ternary complex recruitment in vivo.
abstract: Translation initiation factor 1A (eIF1A) is predicted to bind in the decoding site of the 40S ribosome and has been implicated in recruitment of the eIF2-GTP-Met-tRNA i Met ternary complex (TC) and ribosomal scanning. We show that the unstructured C-terminus of eIF1A interacts with the C-terminus of eIF5B, a factor that stimulates 40S-60S subunit joining, and removal of this domain of eIF1A diminishes translation initiation in vivo. These findings support the idea that eIF1A-eIF5B association is instrumental in releasing eIF1A from the ribosome after subunit joining. A larger C-terminal truncation that removes a 3(10) helix in eIF1A deregulates GCN4 translation in a manner suppressed by overexpressing TC, implicating eIF1A in TC binding to 40S ribosomes in vivo. The unstructured N-terminus of eIF1A interacts with eIF2 and eIF3 and is required at low temperatures for a step following TC recruitment. We propose a modular organization for eIF1A wherein a core ribosome-binding domain is flanked by flexible segments that mediate interactions with other factors involved in recruitment of TC and release of eIF1A at subunit joining.
authors.affiliation: Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, Bethesda, MD 20892, USA.
authors.forename: DeAnne S
authors.initials: DS
authors.lastname: Olsen
authors.forename: Erin M
authors.initials: EM
authors.lastname: Savner
authors.forename: Amy
authors.initials: A
authors.lastname: Mathew
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.forename: Thanuja
authors.initials: T
authors.lastname: Krishnamoorthy
authors.forename: Lon
authors.initials: L
authors.lastname: Phan
authors.forename: Alan G
authors.initials: AG
authors.lastname: Hinnebusch
mesh_terms: D001665:Binding Sites; D015977:Eukaryotic Initiation Factor-1; D015852:Eukaryotic Initiation Factor-2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D039621:Eukaryotic Initiation Factor-3 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D040061:Eukaryotic Initiation Factor-5 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D046911:Macromolecular Substances; D010442:Peptide Chain Initiation, Translational; D010448:Peptide Initiation Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D011485:Protein Binding; D014176:Protein Biosynthesis; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D015977:Eukaryotic Initiation Factor-1; D015852:Eukaryotic Initiation Factor-2; D039621:Eukaryotic Initiation Factor-3; D040061:Eukaryotic Initiation Factor-5; D046911:Macromolecular Substances; D010448:Peptide Initiation Factors; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C026022:eukaryotic peptide initiation factor-1A