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Journal of Theoretical Biology 245 (2007) 169174 The evolution of the genetic code took place in

Summary: Journal of Theoretical Biology 245 (2007) 169174
The evolution of the genetic code took place in
an anaerobic environment
Marco Archettia
, Massimo Di Giuliob,
Department of Zoology, Oxford University, South Parks Road, OX1 3PS Oxford, UK
Institute of Genetics and Biophysics `Adriano Buzzati Traverso', CNR, Via P. Castellino, 111, 80131 Naples, Napoli, Italy
Received 10 July 2006; received in revised form 21 September 2006; accepted 22 September 2006
Available online 24 September 2006
We have compared orthologous proteins from an aerobic organism, Cytophaga hutchinsonii, and from an obligate anaerobe,
Bacteroides thetaiotaomicron. This comparison allows us to define the oxyphobic ranks of amino acids, i.e. a scale of the relative
sensitivity to oxygen of the amino acid residues. The oxyphobic index (OI), which can be simply obtained from the amino acids'
oxyphobic ranks, can be associated to any protein and therefore to the genetic code, if the number of synonymous codons attributed to
the amino acids in the code is assumed to be the frequency with which the amino acids appeared in ancestral proteins. Sampling of the OI
variable from the proteins of obligate anaerobes and aerobes has established that the OI value of the genetic code is not significantly
different from the mean OI value of anaerobe proteins, while it is different from that of aerobe proteins. This observation would seem to
suggest that the terminal phases of the evolution of genetic code organization took place in an anaerobic environment. This result is


Source: Archetti, Marco - Department of Organismic and Evolutionary Biology, Harvard University


Collections: Biology and Medicine