Saturation of recognition elements blocks evolution of new tRNA identities

Saint-Léger, Adélaïde; Bello, Carla, 1990-; Dans, Pablo D.; Gabriel Torres, Adrian; Novoa, Eva Maria; Camacho, Noelia; Orozco, Modesto; Kondrashov, Fyodor A., 1979-; Ribas de Pouplana, Lluís

doi:http://dx.doi.org/10.1126/sciadv.1501860

Saturation of recognition elements blocks evolution of new tRNA identities

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Saint-Léger A, Bello Cabrera C, Dans PD, Gabriel Torres A, Novoa EM, Camacho N, Orozco M, Kondrashov FA, Ribas de Pouplana L. Saturation of recognition elements blocks evolution of new tRNA identities. Science Advances. 2016;2(4):e1501860. DOI: 10.1126/sciadv.1501860

Abstract

Understanding the principles that led to the current complexity of the genetic code is a central question in evolution. Expansion of the genetic code required the selection of new transfer RNAs (tRNAs) with specific recognition signals that allowed them to be matured, modified, aminoacylated, and processed by the ribosome without compromising the fidelity or efficiency of protein synthesis. We show that saturation of recognition signals blocks the emergence of new tRNA identities and that the rate of nucleotide substitutions in tRNAs is higher in species with fewer tRNA genes. We propose that the growth of the genetic code stalled because a limit was reached in the number of identity elements that can be effectively used in the tRNA structure.