title: Energetic contribution of tRNA hybrid state formation to translocation catalysis on the ribosome.
abstract: Upon transpeptidylation, the 3' end of aminoacyl-tRNA (aa-tRNA) in the ribosomal A site enters the A/P hybrid state. We report that transpeptidylation of Phe-tRNA to fMetPhe-tRNA on Escherichia coli ribosomes substantially lowers the kinetic stability of the ribosome-tRNA complex and decreases the affinity by 18.9 kJ mol(-1). At the same time, the free energy of activation of elongation factor G dependent translocation decreases by 12.5 kJ mol(-1), indicating that part of the free energy of transpeptidylation is used to drive translocation kinetically. Thus, the formation of the A/P hybrid state constitutes an important element of the translocation mechanism.
authors.affiliation: Institute of Molecular Biology, University of Witten/Herdecke, D-58448 Witten, Germany.
authors.forename: Y P
authors.initials: YP
authors.lastname: Semenkov
authors.forename: M V
authors.initials: MV
authors.lastname: Rodnina
authors.forename: W
authors.initials: W
authors.lastname: Wintermeyer
mesh_terms: D001665:Binding Sites; D002384:Catalysis / Q000187:drug effects; D004926:Escherichia coli / Q000235:genetics; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D010441:Peptide Chain Elongation, Translational / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D012358:RNA, Transfer, Met / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012360:RNA, Transfer, Phe / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism*; D013096:Spermine / Q000494:pharmacology; D013816:Thermodynamics
chemical_list: D012358:RNA, Transfer, Met; D012360:RNA, Transfer, Phe; C089238:fMet-tRNA(fMet); D013096:Spermine; D008274:Magnesium