PMID: 27662086

Authors:

Hussain T, Llacer JL, Wimberly BT, Kieft JS, Ramakrishnan V

Title:

Large-Scale Movements of IF3 and tRNA during Bacterial Translation Initiation.

Journal:

Cell. 2016 Sep 22;167(1):133-144.e13. doi: 10.1016/j.cell.2016.08.074.

Abstract:

In bacterial translational initiation, three initiation factors (IFs 1-3) enable the selection of initiator tRNA and the start codon in the P site of the 30S ribosomal subunit. Here, we report 11 single-particle cryo-electron microscopy (cryoEM) reconstructions of the complex of bacterial 30S subunit with initiator tRNA, mRNA, and IFs 1-3, representing different steps along the initiation pathway. IF1 provides key anchoring points for IF2 and IF3, thereby enhancing their activities. IF2 positions a domain in an extended conformation appropriate for capturing the formylmethionyl moiety charged on tRNA. IF3 and tRNA undergo large conformational changes to facilitate the accommodation of the formylmethionyl-tRNA (fMet-tRNA(fMet)) into the P site for start codon recognition.