Re: Evolution of the genetic code Re: DNA sequence space

From: Pim van Meurs <>
Date: Sat Oct 01 2005 - 17:40:48 EDT

Oops once again I forgot the references

Massimo Di Giulio "The origin of the genetic code: theories and their
relationships, a review" Biosystems Volume 80, Issue 2 , May 2005, Pages


A review of the main theories proposed to explain the origin of the
genetic code is presented. I analyze arguments and data in favour of
different theories proposed to explain the origin of the organization of
the genetic code. It is possible to suggest a mechanism that makes
compatible the different theories of the origin of the code, even if
these are based on a historical or physicochemical determinism and thus
appear incompatible by definition. Finally, I discuss the question of
why a given number of synonymous codons was attributed to the amino
acids in the genetic code.

2005 The triplet genetic code had a doublet predecessor Patel, A.
Journal of Theoretical Biology 233 (4), pp. 527-532


Information theoretic analysis of genetic languages indicates that the
naturally occurring 20 amino acids and the triplet genetic code arose by
duplication of 10 amino acids of class-II and a doublet genetic code
having codons NNY and anticodons GNN←. Evidence for this scenario is
presented based on the properties of aminoacyl-tRNA synthetases, amino
acids and nucleotide bases.

2005 A mechanism for the association of amino acids with their codons
and the origin of the genetic code
Copley, S.D., Smith, E., Morowitz, H.J. Proceedings of the National
Academy of Sciences of the United States of America 102 (12), pp. 4442-4447


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 macromoleculss, simple
amino acids were synthesized in covalern complexes of dinucleotides with
α-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.

2005 A universal trend of amino acid gain and loss in protein evolution
Jordan, I.K., Kondrashov, F.A., Adzhubei, I.A., Wolf, Y.I., Koonin,
E.V., Kondrashov, A.S., Sunyaev, S. Nature 433 (7026), pp. 633-638

2005 Origins of the genetic code: The escaped triplet theory Yarus, M.,
Caporaso, J.G., Knight, R. Annual Review of Biochemistry 74 pp. 179-198
Received on Sat Oct 1 17:42:22 2005

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