Translational initiation factor eIF5 replaces eIF1 on the 40S ribosomal subunit to promote start-codon recognition.

ABSTRACT: In eukaryotic translation initiation, AUG recognition of the mRNA requires accommodation of Met-tRNA_i in a 'P_IN' state, which is antagonized by the factor eIF1. eIF5 is a GTPase activating protein (GAP) of eIF2 that additionally promotes stringent AUG selection, but the molecular basis of its dual function was unknown. We present a cryo-electron microscopy (cryo-EM) reconstruction of a yeast 48S pre-initiation complex (PIC), at an overall resolution of 3.0 Å, featuring the N-terminal domain (NTD) of eIF5 bound to the 40S subunit at the location vacated by eIF1. eIF5 interacts with and allows a more accommodated orientation of Met-tRNA_i. Substitutions of eIF5 residues involved in the eIF5-NTD/tRNA_i interaction influenced initiation at near-cognate

SUBMITTER: Llacer JL 

PROVIDER: S-EPMC6298780 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature