title: Novel roles for classical factors at the interface between translation termination and initiation.
abstract: The pathway of bacterial ribosome recycling following translation termination has remained obscure. Here, we elucidate two essential steps and describe the roles played by the three translation factors EF-G, RRF, and IF3. Release factor RF3 is known to catalyze the dissociation of RF1 or RF2 from ribosomes after polypeptide release. We show that the next step is dissociation of 50S subunits from the 70S posttermination complex and that it is catalyzed by RRF and EF-G and requires GTP hydrolysis. Removal of deacylated tRNA from the resulting 30S:mRNA:tRNA posttermination complex is then necessary to permit rapid 30S subunit recycling. We show that this step requires initiation factor IF3, whose role was previously thought to be restricted to promoting specific 30S initiation complex formation from free 30S subunits.
authors.affiliation: Department of Cell and Molecular Biology, Biomedical Center, Uppsala, Sweden.
authors.forename: R
authors.initials: R
authors.lastname: Karimi
authors.forename: M Y
authors.initials: MY
authors.lastname: Pavlov
authors.forename: R H
authors.initials: RH
authors.lastname: Buckingham
authors.forename: M
authors.initials: M
authors.lastname: Ehrenberg
mesh_terms: D000107:Acetylation; D001483:Base Sequence; D018387:Codon, Initiator; D004926:Escherichia coli; D039621:Eukaryotic Initiation Factor-3; D015964:Gene Expression Regulation, Bacterial; D006147:Guanine / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000378:metabolism; D006868:Hydrolysis; D008969:Molecular Sequence Data; D020653:Peptide Elongation Factor G; D010445:Peptide Elongation Factors / Q000235:genetics*; D010448:Peptide Initiation Factors / Q000235:genetics*; D014176:Protein Biosynthesis / Q000187:drug effects / Q000235:genetics*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000235:genetics*; D011691:Puromycin / Q000494:pharmacology; D012343:RNA, Transfer / Q000235:genetics; D012269:Ribosomal Proteins / Q000235:genetics; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism
chemical_list: D018387:Codon, Initiator; D039621:Eukaryotic Initiation Factor-3; D020653:Peptide Elongation Factor G; D010445:Peptide Elongation Factors; D010448:Peptide Initiation Factors; D011500:Protein Synthesis Inhibitors; D011506:Proteins; D012269:Ribosomal Proteins; C040469:ribosomal protein S30; C087267:ribosome releasing factor; D011691:Puromycin; D006147:Guanine; D006160:Guanosine Triphosphate; D012343:RNA, Transfer