Trial for peptide bond formation using model molecules based on the interactions between the CCA sequence of tRNA and 23S rRNA.

The peptidyl transfer reaction catalyzed by the ribosome is a sophisticated product of evolution. The molecular mechanism of peptide bond formation has not been fully elucidated although the essential involvement of 23S rRNA has been established. The universal CCA sequence at the 3'-end of tRNA plays an important role in this process, by interacting with specific nucleotides in 23S rRNA. However, reconstitution of peptidyl transferase activity by a naked 23S rRNA (without the help of any of the ribosomal proteins) has not been reported. To investigate the possible evolutionary development of the peptidyl transfer reaction, we tried to obtain peptide bond formation using a piece of tRNA--an aminoacyl-minihelix--mixed with sequence-specific oligonucleotides that contained puromycin. This system reproduced conceptually the equivalent interactions between the CCA trinucleotide of tRNA and 23S rRNA. Peptide bond formation was detected by gel electrophoresis, TLC and mass spectrometry. These results have implications for the evolution of the peptidyl transfer reaction in biological system.