A tiny RNA that catalyzes both aminoacyl-RNA and peptidyl-RNA synthesis

A 29-nt RNA catalyst successively forms the aminoacyl ester phe-RNA, and then peptidyl-RNA (phe-phe-RNA), given phenylalanine adenylate (phe-AMP) as substrate. Catalysis of two related reactions at similar rates supports the argument that RNA catalysts would evolve as groups with similar mechanisms. In particular, successive aminoacyl- and peptidyl-RNA synthesis by one RNA suggests that uncoded but RNA-catalyzed peptide synthesis would evolve before the synthesis of coded peptides.