Abstract

Horizontal gene transfer plays a potent role in the evolution of prokaryotes. A rigorous sequence and phylogenetic analysis was carried out using the robust clustalW, motifs/domains finding suites and neighbor-joining based ProtDist and BioNJ. This paper reports a few cases of horizontal gene transfer events between archaea and bacteria. Some of these events have been found to be unique to the bacterial pathogenic members and have not been observed in respective non-pathogenic counterparts. Two cases have been shown to exhibit particular importance. The first one is a Cps4I gene that codes for capsule polysaccharide biosynthesis protein in Streptococcus pneumoniae. The other gene has been detected in Streptococcus agalactiae that codes for N-acetyl neuramic acid synthetase, which is involved in the synthesis of N-acetyl neuramic acid or sialic acid. We believe that these genes, having been retained in the genome through selective advantage, have key functions in the organism’s biology and may play a role in pathogenesis.

Key words: Horizontal gene transfer, BLAST, ClustalW, conserved domain, motif, bootstrap value, bit score.