caa a22 4500 445820896 CHVBK 20180317145243.0 cr unu---uuuuu 170323e20111001xx s 000 0 eng 10.1007/s00239-011-9470-3 doi (NATIONALLICENCE)springer-10.1007/s00239-011-9470-3 Unassigned Codons, Nonsense Suppression, and Anticodon Modifications in the Evolution of the Genetic Code [Elektronische Daten] [Peter van der Gulik, Wouter Hoff] The origin of the genetic code is a central open problem regarding the early evolution of life. Here, we consider two undeveloped but important aspects of possible scenarios for the evolutionary pathway of the translation machinery: the role of unassigned codons in early stages of the code and the incorporation of tRNA anticodon modifications. As the first codons started to encode amino acids, the translation machinery likely was faced with a large number of unassigned codons. Current molecular scenarios for the evolution of the code usually assume the very rapid assignment of all codons before all 20 amino acids became encoded. We show that the phenomenon of nonsense suppression as observed in current organisms allows for a scenario in which many unassigned codons persisted throughout most of the evolutionary development of the code. In addition, we demonstrate that incorporation of anticodon modifications at a late stage is feasible. The wobble rules allow a set of 20 tRNAs fully lacking anticodon modifications to encode all 20 canonical amino acids. These observations have implications for the biochemical plausibility of early stages in the evolution of the genetic code predating tRNA anticodon modifications and allow for effective translation by a relatively small and simple early tRNA set. Springer Science+Business Media, LLC, 2011 Genetic code nationallicence Unassigned codons nationallicence Wobble rules nationallicence Evolution nationallicence RNA modification nationallicence tRNA nationallicence van der Gulik Peter Centrum Wiskunde & Informatica (CWI), P.O. Box 94079, 1090 GB, Amsterdam, The Netherlands aut Hoff Wouter Department of Microbiology and Molecular Genetics, Oklahoma State University, 74078, Stillwater, OK, USA aut Journal of Molecular Evolution Springer-Verlag 73/3-4(2011-10-01), 59-69 0022-2844 73:3-4<59 2011 73 239 https://doi.org/10.1007/s00239-011-9470-3 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00239-011-9470-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- van der Gulik Peter Centrum Wiskunde & Informatica (CWI), P.O. Box 94079, 1090 GB, Amsterdam, The Netherlands aut NATIONALLICENCE 700 1- Hoff Wouter Department of Microbiology and Molecular Genetics, Oklahoma State University, 74078, Stillwater, OK, USA aut NATIONALLICENCE 773 0- Journal of Molecular Evolution Springer-Verlag 73/3-4(2011-10-01), 59-69 0022-2844 73:3-4<59 2011 73 239 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer