A universal trend of amino acid gain and loss in protein evolution

摘要: A comparison of corresponding sets proteins encoded by closely related genes from organisms representing all three domains life (Bacteria, Archaea and Eukaryota) suggests that the order in which genetic code was assembled over 3.5 billion years ago continues to influence evolution today. Across these diverse genomes, evolving have accumulated Cys, Met, His, Ser Phe, lost many their Pro, Ala, Glu Gly residues. The same nine amino acids are currently accrued or human as shown analysis nucleotide polymorphisms. with declining frequencies were probably among first incorporated into code, most those increasing recruited late. Amino acid composition varies substantially between taxa and, thus, can evolve. For example, (G + C)-rich (or (A T)-rich) genomes contain more fewer) codons1,2,3,4. However, no universal trends ongoing changes been reported. We compared orthologous triplets 15 Eukaryota), used phylogenies polarize substitutions. Phe accrue at least 14 taxa, whereas consistently lost. proteins, non-synonymous single-nucleotide All thought be code; conversely, frequencies, except Ser, late5,6,7. Thus, expansion initially under-represented acids, began 3,400 million ago8,9, apparently this day.