title: Translation arrest requires two-way communication between a nascent polypeptide and the ribosome.
abstract: When the export of E. coli SecM is blocked, a 17 amino acid motif near the C terminus of the protein induces a translation arrest from within the ribosome tunnel. Here we used a recently described application of fluorescence resonance energy transfer (FRET) to gain insight into the mechanism of translation arrest. We found that the SecM C terminus adopted a compact conformation upon synthesis of the arrest motif. This conformational change did not occur spontaneously, but rather was induced by the ribosome. Translation arrest required both compaction of the SecM C terminus and the presence of key residues in the arrest motif. Further analysis showed that the arrested peptidyl-tRNA was resistant to puromycin treatment and revealed additional changes in the ribosome-nascent SecM complex. Based on these observations, we propose that translation arrest results from a series of reciprocal interactions between the ribosome and the C terminus of the nascent SecM polypeptide.
authors.affiliation: Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Cheryl A
authors.initials: CA
authors.lastname: Woolhead
authors.forename: Arthur E
authors.initials: AE
authors.lastname: Johnson
authors.forename: Harris D
authors.initials: HD
authors.lastname: Bernstein
mesh_terms: D020816:Amino Acid Motifs / Q000502:physiology; D000595:Amino Acid Sequence; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D010441:Peptide Chain Elongation, Translational / Q000502:physiology; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D011487:Protein Conformation; D012270:Ribosomes / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029968:Escherichia coli Proteins; D005456:Fluorescent Dyes; D010455:Peptides; C497347:SecM protein, E coli; D014157:Transcription Factors