title: Saturation of recognition elements blocks evolution of new tRNA identities.
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.
authors.affiliation: Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain.
authors.forename: Adélaïde
authors.initials: A
authors.lastname: Saint-Léger
authors.affiliation: Bioinformatics and Genomics Programme, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, 88 Dr. Aiguader, 08003 Barcelona, Catalonia, Spain.; Universitat Pompeu Fabra, 08003 Barcelona, Catalonia, Spain.
authors.forename: Carla
authors.identifier: 0000-0002-3515-9025
authors.initials: C
authors.lastname: Bello
authors.affiliation: Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain.; Joint BSC-IRB Research Program in Computational Biology, Institute for Research in Biomedicine (IRB Barcelona), Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain.
authors.forename: Pablo D
authors.identifier: 0000-0002-5927-372X
authors.initials: PD
authors.lastname: Dans
authors.affiliation: Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain.
authors.forename: Adrian Gabriel
authors.initials: AG
authors.lastname: Torres
authors.affiliation: Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain.; Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, 32 Vassar Street, Cambridge, MA 02139, USA.; Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02139, USA.
authors.forename: Eva Maria
authors.identifier: 0000-0001-5567-1299
authors.initials: EM
authors.lastname: Novoa
authors.affiliation: Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain.
authors.forename: Noelia
authors.initials: N
authors.lastname: Camacho
authors.affiliation: Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain.; Joint BSC-IRB Research Program in Computational Biology, Institute for Research in Biomedicine (IRB Barcelona), Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain.; Departament de Bioquimica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona, Avgda Diagonal 647, 08028 Barcelona, Catalonia, Spain.
authors.forename: Modesto
authors.identifier: 0000-0002-8608-3278
authors.initials: M
authors.lastname: Orozco
authors.affiliation: Bioinformatics and Genomics Programme, Centre for Genomic Regulation, Barcelona Institute of Science and Technology, 88 Dr. Aiguader, 08003 Barcelona, Catalonia, Spain.; Universitat Pompeu Fabra, 08003 Barcelona, Catalonia, Spain.; Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluis Companys 23, 08010 Barcelona, Catalonia, Spain.
authors.forename: Fyodor A
authors.initials: FA
authors.lastname: Kondrashov
authors.affiliation: Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, Baldiri Reixac 10, 08028 Barcelona, Catalonia, Spain.; Catalan Institution for Research and Advanced Studies (ICREA), Passeig Lluis Companys 23, 08010 Barcelona, Catalonia, Spain.
authors.forename: Lluís
authors.initials: L
authors.lastname: Ribas de Pouplana
mesh_terms: D019143:Evolution, Molecular; D005815:Genetic Code; D009690:Nucleic Acid Conformation; D012343:RNA, Transfer / Q000235:genetics*
chemical_list: D012343:RNA, Transfer
keywords: ADAT; evolution; genetic code; tRNA Gly; tRNA identities