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Domains of eIF1A that mediate binding to eIF2, eIF3 and eIF5B and promote ternary complex recruitment in vivo
Author(s) -
Olsen DeAnne S.,
Savner Erin M.,
Mathew Amy,
Zhang Fan,
Krishnamoorthy Thanuja,
Phan Lon,
Hinnebusch Alan G.
Publication year - 2003
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdg030
Subject(s) - biology , eukaryotic small ribosomal subunit , eif2 , eukaryotic initiation factor , microbiology and biotechnology , ribosome , protein subunit , initiation factor , genetics , rna , gene
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.