Molecular insight to influential role of Hha–TomB toxin–antitoxin system for antibacterial activity of biogenic silver nanoparticles

Abstract

Emergence of silver nanoparticles (AgNPs) as a potent antibacterial agent for clinical application has raised attention towards its mode of action and needs detailed understanding of the mechanism. The current study investigates the influential role of Hha–TomB toxin–antitoxin system in determination of AgNPs antibacterial activity. AgNPs were synthesized by biogenic process using bacterial supernatant and were characterized for their physiochemical properties. Microbiological and computational assays like molecular docking, growth curve analysis, live/dead assay, oxidative stress and apoptosis assay were performed with wild type (WT) and mutants (Δhha, ΔtomB) strains treated with AgNPs for elucidation of mechanism. Stable AgNPs having size 30–40 nm and zeta potential –32 ± 09 mV were synthesized. AgNPs have shown significant antibacterial activity against S. typhimurium. Influential role of Hha–TomB TA proteins was observed in antibacterial effect by their altered expression level change in ROS level and programmed cell death. Molecular investigation elucidated the effect of AgNPs as consequence of their interaction with cellular proteins with different amino acids via hydrophobic interaction leading to alteration of cellular metabolic processes like ROS induction and apoptosis causing ultimate death. The study provided a detail illustration of Hha–TomB TA system influence on antibacterial mechanism of AgNPs for wide spectrum clinical application.