Domains of eIF1A that mediate binding to eIF2, eIF3 and eIF5B and promote ternary complex recruitment in vivo.
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.
Olsen
DeAnne S
DS
Laboratory of Gene Regulation and Development, National Institute of Child Health and Human Development, Bethesda, MD 20892, USA.
Savner
Erin M
EM
Mathew
Amy
A
Zhang
Fan
F
Krishnamoorthy
Thanuja
T
Phan
Lon
L
Hinnebusch
Alan G
AG
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
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