Peptidyl transferase activity catalyzed by protein-free 23S ribosomal RNA remains elusive

In two recent articles by Nitta et al. (1998a, 1998b), evidence was presented that in vitro-transcribed protein-free 23S rRNA of Escherichia coli (and its individual domains) can catalyze peptide bond formation. The implications of these studies are considerable because demonstration of catalytic activity associated with protein-free 23S rRNA would be fundamental to our understanding of the mechanism and evolution of protein synthesis (Noller et al., 1992; Khaitovich et al., 1999).