Translational termination without a stop codon.
Article Details
- CitationCopy to clipboard
James NR, Brown A, Gordiyenko Y, Ramakrishnan V
Translational termination without a stop codon.
Science. 2016 Dec 16;354(6318):1437-1440. Epub 2016 Dec 1.
- PubMed ID
- 27934701 [ View in PubMed]
- Abstract
Ribosomes stall when they encounter the end of messenger RNA (mRNA) without an in-frame stop codon. In bacteria, these "nonstop" complexes can be rescued by alternative ribosome-rescue factor A (ArfA). We used electron cryomicroscopy to determine structures of ArfA bound to the ribosome with 3'-truncated mRNA, at resolutions ranging from 3.0 to 3.4 angstroms. ArfA binds within the ribosomal mRNA channel and substitutes for the absent stop codon in the A site by specifically recruiting release factor 2 (RF2), initially in a compact preaccommodated state. A similar conformation of RF2 may occur on stop codons, suggesting a general mechanism for release-factor-mediated translational termination in which a conformational switch leads to peptide release only when the appropriate signal is present in the A site.