Substrate-assisted catalysis of peptide bond formation by the ribosome
Weinger JS, Parnell KM, Dorner S, Green R, Strobel SA
Nature Structural and Molecular Biology (2004)
Category: ribosomal RNA, translation ¤ Added: Nov 16, 2006 ¤ Rating: ◊◊
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.