caa a22 4500 445821078 CHVBK 20180317145244.0 cr unu---uuuuu 170323e20110801xx s 000 0 eng 10.1007/s00239-011-9453-4 doi (NATIONALLICENCE)springer-10.1007/s00239-011-9453-4 Erives Albert Department of Biological Sciences, Dartmouth College, 03755, Hanover, NH, USA aut A Model of Proto-Anti-Codon RNA Enzymes Requiring l -Amino Acid Homochirality [Elektronische Daten] [Albert Erives] All living organisms encode the 20 natural amino acid units of polypeptides using a universal scheme of triplet nucleotide "codons”. Disparate features of this codon scheme are potentially informative of early molecular evolution: (i) the absence of any codons for d-amino acids; (ii) the odd combination of alternate codon patterns for some amino acids; (iii) the confinement of synonymous positions to a codon's third nucleotide; (iv) the use of 20 specific amino acids rather than a number closer to the full coding potential of 64; and (v) the evolutionary relationship of patterns in stop codons to amino acid codons. Here I propose a model for an ancestral proto-anti-codon RNA (pacRNA) auto-aminoacylation system and show that pacRNAs would naturally manifest features of the codon table. I show that pacRNAs could implement all the steps for auto-aminoacylation: amino acid coordination, intermediate activation of the amino acid by the 5′-end of the pacRNA, and 3′-aminoacylation of the pacRNA. The anti-codon cradles of pacRNAs would have been able to recognize and coordinate only a small number of l-amino acids via hydrogen bonding. A need for proper spatial coordination would have limited the number of chargeable amino acids for all anti-codon sequences, in addition to making some anti-codon sequences unsuitable. Thus, the pacRNA model implies that the idiosyncrasies of the anti-codon table and l-amino acid homochirality co-evolved during a single evolutionary period. These results further imply that early life consisted of an aminoacylated RNA world with a richer enzymatic potential than ribonucleotides alone. The Author(s), 2011 RNA world nationallicence Proto-anti-codons nationallicence Homochirality nationallicence Molecular evolution nationallicence Ribozymes nationallicence Journal of Molecular Evolution Springer-Verlag 73/1-2(2011-08-01), 10-22 0022-2844 73:1-2<10 2011 73 239 https://doi.org/10.1007/s00239-011-9453-4 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00239-011-9453-4 text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Erives Albert Department of Biological Sciences, Dartmouth College, 03755, Hanover, NH, USA aut NATIONALLICENCE 773 0- Journal of Molecular Evolution Springer-Verlag 73/1-2(2011-08-01), 10-22 0022-2844 73:1-2<10 2011 73 239 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer