title: Linkage, mobility, and selfishness in the MazF family of bacterial toxins: a snapshot of bacterial evolution.
abstract: Prokaryotic MazF family toxins cooccur with cognate antitoxins having divergent DNA-binding folds and can be of chromosomal or plasmid origin. Sequence similarity search was carried out to identify the Toxin-Antitoxin (TA) operons of MazF family followed by sequence analysis and phylogenetic studies. The genomic DNA upstream of the TA operons was searched for the presence of regulatory motifs. The MazF family toxins showed a conserved hydrophobic pocket in a multibinding site and are present in pathogenic bacteria. The toxins of the MazF family are associated with four main types of cognate antitoxin partners and cluster as a subfamily on the branches of the phylogenetic tree. This indicates that transmission of the entire operon is the dominant mode of inheritance. The plasmid borne TA modules were interspersed between the chromosomal TA modules of the same subfamily, compatible with a frequent interchange of TA genes between the chromosome and the plasmid akin to that observed for antibiotic resistance gens. The split network of the MazF family toxins showed the AbrB-linked toxins as a hub of horizontal gene transfer. Distinct motifs are present in the upstream region of each subfamily. The presence of MazF family TA modules in pathogenic bacteria and identification of a conserved binding pocket are significant for the development of novel antibacterials to disrupt the TA interaction. However, the role of TAs in stress resistance needs to be established. Phylogenetic studies provide insight into the evolution of MazF family TAs and effect on the bacterial genome.
authors.affiliation: Computational and Structural Biology Laboratory, Division of Biotechnology, Netaji Subhas Institute of Technology, Dwarka, New Delhi, India.
authors.forename: Nikita
authors.initials: N
authors.lastname: Chopra
authors.lastname: Saumitra
authors.forename: Abhinandan
authors.initials: A
authors.lastname: Pathak
authors.forename: Rakesh
authors.initials: R
authors.lastname: Bhatnagar
authors.forename: Sonika
authors.initials: S
authors.lastname: Bhatnagar
mesh_terms: D001408:Bacillus anthracis / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics; D001427:Bacterial Toxins / Q000737:chemistry / Q000145:classification / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000145:classification / Q000235:genetics; D004722:Endoribonucleases / Q000737:chemistry / Q000145:classification / Q000235:genetics; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000145:classification / Q000235:genetics; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal; D008040:Genetic Linkage; D016680:Genome, Bacterial; D008958:Models, Molecular; D010802:Phylogeny; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D017422:Sequence Analysis, DNA
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C422955:MazF protein, E coli; D004722:Endoribonucleases
keywords: MazF; linkage; mobility; multibinding site; phylogenetic studies; toxin–antitoxin systems