Origin and evolution of the Peptidyl Transferase Center from proto-tRNAs

• We tested the proposal that the Peptidyl Transferase Center (PTC) originated from proto-tRNAs.
• Proto-tRNA ancestors were reconstructed.
• Their sequences were compared to the sequences of the PTC from several organisms.
• We conclude that fusions of proto-tRNAs may have given rise to the PTC.

We tested the hypothesis of Tamura (2011) [3] that molecules of tRNA gave origin to ribosomes, particularly to the Peptidyl Transferase Center (PTC) of the 23S ribosomal RNA. We reconstructed the ancestral sequences from all types of tRNA and compared them in their sequences with the current PTC of 23S ribosomal RNA from different organisms. We built an ancestral sequence of proto-tRNAs that showed a remarkable overall identity of 50.53% with the catalytic site of PTC. We conclude that the Peptidyl Transferase Center was indeed originated by the fusion of ancestral sequences of proto-tRNA.