Classification of bacteria based on the biases of terminal amino acid residues

The frequencies of amino acid residues are known to be biased at both terminal regions of amino acid sequences deduced from bacterial genomic DNA. To investigate whether or not the features of biases of amino acid residues at the terminal regions are related to the bacterial phylogeny, we calculated the normalized amino acid compositions at both terminal regions, and used these compositions to classify 144 bacteria by hierarchical clustering analysis. Our results showed that most of these bacteria were classified into taxonomic classes by the hierarchical clustering analysis that was based on the normalized amino acid compositions at the N-terminal region. Therefore, we concluded that the features of biases of the N-terminal amino acid residues were related to the bacterial phylogeny.