Work

Translational termination without a stop codon

Year: 2016

Type: article

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.

Source: Science

DOI: 10.1126/science.aai9127

Authors: Nathan R. James, Alan Brown, Yuliya Gordiyenko, V. Ramakrishnan

Institutions: MRC Laboratory of Molecular Biology, Medical Research Council

Language: English

Topic: RNA and protein synthesis mechanisms

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

Open Access status: green

Funders: Agouron Institute, Wellcome Trust, Louis-Jeantet Foundation, Medical Research Council

Awards: G1956668798, Structure and function of ribosomes., G5524861217, Structure and function of ribosomes., Structural studies on ribosomes.