Title:Phylogenetic Approach for Inferring the Origin and Functional Evolution of Bacterial ADP-ribosylation Superfamily
Volume: 20
Issue: 9
Author(s): P. Chellapandi, S. Sakthishree and M. Bharathi
Affiliation:
Keywords:
Functional divergence, phylogeny, ADP-ribosylation, molecular evolution, compensation mutation, bacterial toxins.
Abstract: Bacterial ADP-ribosyltransferases (BADPRTs) are extensively contributed to determine the strain-specific
virulence state and pathogenesis in human hosts. Understanding molecular evolution and functional diversity of the
BADPRTs is an important standpoint to describe the fundamental behind in the vaccine designing for bacterial infections.
In the present study, we have evaluated the origin and functional evolution of conserved domains within the BADPRTs by
analyzing their sequence-function relationship. To represent the evolution history of BADPRTs, phylogenetic trees were
constructed based on their protein sequence, structure and conserved domains using different evolutionary programs. Sequence
divergence and genetic diversity were studied herein to deduce the functional evolution of conserved domains
across the family and superfamily. The results of sequence similarity search have shown that three hypothetical proteins
(above 90%) were identical to the members of BADPRTs and their functions were annotated by phylogenetic approach.
Phylogenetic analysis of this study has revealed the family members of BADPRTs were phylogenetically related to one
another, functionally diverged within the same family, and dispersed into closely related bacteria. The presence of core
substitution pattern in the conserved domains would determine the family-specific function of BADPRTs. Functional diversity
of the BADPRTs was exclusively distinguished by Darwinian positive selection (diphtheria toxin C and pertussis
toxin S) and neutral selection (arginine ADP-ribosyltransferase, enterotoxin A and binary toxin A) acting on the existing
domains. Many of the family members were sharing their sequence-specific features from members in the arginine ADPribosyltransferase
family. Conservative functions of members in the BADPRTs have shown to be expanded only within
closely related families, and retained as such in pathogenic bacteria by evolutionary process (domain duplication or recombination
events). Hence, we conclude that evolutionary significance of the members in the BADPRTs would provide
an insight for experimental set-up on site-directed mutagenesis and vaccine engineering.
