Correlation between mutation pressure, selection pressure, and occurrence of amino acids

Abstract

With the help of the empirical mutation table for nucleotides in the Borrelia burgdorferi genome we have performed Monte Carlo simulation of the pure mutation pressure experienced by the genes of the genome. We have examined the divergence of the mutated genes from the ancestral ones and we have constructed MPM1 matrix (Mutation Probability Matrix) of the substitution rates between amino acids of the diverging genes. The results have been compared to mutation data matrix PAM1 PET91 representing mutation and selection data of 16130 homologous genes od different organisms. We have found that the effective survival time of amino acids in organisms follows a power law with respect to frequency of their occurrence in genes. This makes possible to find the effect of the pure mutational pressure and the selection on the amino acid composition of genes. The results are universal in the sense that the survival time of amino acids calculated from the higher order PAMk matrices (k > 1) follows the same power law as in the case of PAM1 matrices. © Springer-Verlag Berlin Heidelberg 2003.