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

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

Author information

1
MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.
2
MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK; Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA.
3
Department of Biochemistry and Molecular Genetics, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA; RNA BioScience Initiative, University of Colorado Denver School of Medicine, Aurora, CO 80045, USA.
4
MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK. Electronic address: ramak@mrc-lmb.cam.ac.uk.

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.

KEYWORDS:

IF1; IF2; IF3; cryo-EM; fMet-tRNA; initiation; ribosome; start codon; structures; translation

PMID:
27662086
PMCID:
PMC5037330
DOI:
10.1016/j.cell.2016.08.074
[Indexed for MEDLINE]
Free PMC Article

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