Substrate-assisted catalysis of peptide bond formation by the ribosome.
The ribosome accelerates the rate of peptide bond formation by at least 10(7)-fold, but the catalytic mechanism remains controversial. Here we report evidence that a functional group on one of the tRNA substrates plays an essential catalytic role in the reaction. Substitution of the P-site tRNA A76 2' OH with 2' H or 2' F results in at least a 10(6)-fold reduction in the rate of peptide bond formation, but does not affect binding of the modified substrates. Such substrate-assisted catalysis is relatively uncommon among modern protein enzymes, but it is a property predicted to be essential for the evolution of enzymatic function. These results suggest that substrate assistance has been retained as a catalytic strategy during the evolution of the prebiotic peptidyl transferase center into the modern ribosome.
Department of Molecular Biophysics and Biochemistry, Yale University, 260 Whitney Avenue, New Haven, Connecticut 06520-8114, USA.
Joshua S
JS
Weinger
K Mark
KM
Parnell
Silke
S
Dorner
Rachel
R
Green
Scott A
SA
Strobel
D001483:Base Sequence; D002384:Catalysis; D020134:Catalytic Domain; D004926:Escherichia coli / Q000378:metabolism; D019143:Evolution, Molecular; D007700:Kinetics; D008239:Lysine / Q000737:chemistry; D008715:Methionine / Q000737:chemistry; D008954:Models, Biological; D008956:Models, Chemical; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D010458:Peptidyl Transferases; D021381:Protein Transport; D012333:RNA, Messenger / Q000378:metabolism; D012343:RNA, Transfer / Q000737:chemistry; D012270:Ribosomes / Q000737:chemistry*; D013379:Substrate Specificity; D013997:Time Factors
D010455:Peptides; D012333:RNA, Messenger; D012343:RNA, Transfer; D008715:Methionine; D010458:Peptidyl Transferases; D008239:Lysine