Kinetic determinants of high-fidelity tRNA discrimination on the ribosome.
The ribosome selects aminoacyl-tRNA (aa-tRNA) matching to the mRNA codon from the bulk of non-matching aa-tRNAs in two consecutive selection steps, initial selection and proofreading. Here we report the kinetic analysis of selection taking place under conditions where the overall selectivity was close to values observed in vivo and initial selection and proofreading contributed about equally. Comparison of the rate constants shows that the 350-fold difference in stabilities of cognate and near-cognate codon-anticodon complexes is not used for tRNA selection due to high rate of GTP hydrolysis in the cognate complex. tRNA selection at the initial selection step is entirely kinetically controlled and is due to much faster (650-fold) GTP hydrolysis of cognate compared to near-cognate substrate.
Gromadski
Kirill B
KB
Institute of Physical Biochemistry, University of Witten/Herdecke, D-58448 Witten, Germany.
Rodnina
Marina V
MV
D001665:Binding Sites; D003062:Codon; D004926:Escherichia coli / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D008954:Models, Biological; D008957:Models, Genetic; D010444:Peptide Elongation Factor Tu / Q000378:metabolism; D011485:Protein Binding; D012333:RNA, Messenger / Q000378:metabolism; D012343:RNA, Transfer / Q000737:chemistry* / Q000378:metabolism; D012346:RNA, Transfer, Amino Acyl / Q000737:chemistry; D012270:Ribosomes / Q000378:metabolism*; D013816:Thermodynamics; D013997:Time Factors
D003062:Codon; D012333:RNA, Messenger; D012346:RNA, Transfer, Amino Acyl; D006160:Guanosine Triphosphate; D012343:RNA, Transfer; D020558:GTP Phosphohydrolases; D010444:Peptide Elongation Factor Tu