title: A conserved base-pair between tRNA and 23 S rRNA in the peptidyl transferase center is important for peptide release.
abstract: The 3' terminus of tRNAs has the universally conserved bases C74C75A76 that interact with the ribosomal large subunit. In the ribosomal P site, bases C74 and C75 of tRNA, form Watson-Crick base-pairs with G2252 and G2251, respectively, present in the conserved P-loop of 23 S rRNA. Previous studies have suggested that the G2252-C74 base-pair is important for peptide bond formation. Using a pure population of mutant ribosomes, we analyzed the precise role of this base-pair in peptide bond formation, elongation factor G-dependent translocation, and peptide release by release factor 1. Surprisingly, our results show that the G2252-C74 base-pair is not essential for peptide bond formation with intact aminoacyl tRNAs as substrates and for EF-G catalyzed translocation. Interestingly, however, peptide release was reduced substantially when base-pair formation between G2252 and C74 of P site tRNA was disrupted, indicating that this conserved base-pair plays an important role in ester bond hydrolysis during translation termination.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0314, USA.
authors.forename: Jason S
authors.initials: JS
authors.lastname: Feinberg
authors.forename: Simpson
authors.initials: S
authors.lastname: Joseph
mesh_terms: D020029:Base Pairing; D001483:Base Sequence; D017124:Conserved Sequence; D004926:Escherichia coli; D016296:Mutagenesis; D009690:Nucleic Acid Conformation; D010441:Peptide Chain Elongation, Translational; D010443:Peptide Chain Termination, Translational; D010446:Peptide Fragments / Q000378:metabolism*; D010458:Peptidyl Transferases / Q000378:metabolism*; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000378:metabolism; D012338:RNA, Ribosomal, 23S / Q000235:genetics / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D012329:RNA, Bacterial; D012338:RNA, Ribosomal, 23S; D012346:RNA, Transfer, Amino Acyl; D010458:Peptidyl Transferases