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A mechanism for the association of amino ... the origin of the genetic code
A mechanism for the association of amino acids with their codons and the origin of the genetic code.
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The genetic code has certain regularities that have resisted mechanistic interpretation. These include strong correlations between the first base of codons and the precursor from which the encoded amino acid is synthesized and between the second base of codons and the hydrophobicity of the encoded amino acid. These regularities are even more striking in a projection of the modern code onto a simpler code consisting of doublet codons encoding a set of simple amino acids. These regularities can be explained if, before the emergence of macromolecules, simple amino acids were synthesized in covalent complexes of dinucleotides with alpha-keto acids originating from the reductive tricarboxylic acid cycle or reductive acetate pathway. The bases and phosphates of the dinucleotide are proposed to have enhanced the rates of synthetic reactions leading to amino acids in a small-molecule reaction network that preceded the RNA translation apparatus but created an association between amino acids and the first two bases of their codons that was retained when translation emerged later in evolution.
Copley SD, Smith E, Morowitz HJ
Proceedings of the National Academy of Sciences of the United States of America
2005-03-22 00:00
102
12
4442-7
Amino Acids,Codon,Decarboxylation,Decision Trees,Evolution, Molecular,Genetic Code,Keto Acids,Models, Biological,Models, Genetic,Phosphorylation,Pyruvic Acid,Amino Acids,Codon,Keto Acids,Pyruvic Acid
Cooperative Institute for Research in Environmental Sciences, Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA shelleycirescoloradoau
Proc. Natl. Acad. Sci. U.S.A.
0027-8424
10.1073/pnas.0501049102
0501049102
320
True
15764708
