ABSTRACT
Type II toxin-antitoxin (TA) systems are the particular type of TA modules which take part in different kinds of cellular actions, such as biofilm formation, persistence, stress endurance, defense of the bacterial cell against multiple phage attacks, plasmid maintenance, and programmed cell death in favor of bacterial population. Although several bioinformatics and Pet lab studies have already been conducted to understand the functionality of already discovered TA systems, still, more work in this area is required. Rnl AB type II TA module, which is composed of RnlA toxin and RnlB antitoxin, is a newly discovered type II TA module which takes part in the defense mechanism against T4 bacteriophage attack in Escherichia coli K-12 strain MH1 that has not been widely studied in other bacteria. Because of the significant role of class Gammaproteobacteriacea in a diverse range of health problems, we chose here to focus on this class to survey the presence of the Rnl AB TA module. For better categorization and description of the distribution of this module in this class of bacteria, the corresponding phylogenetic trees are illustrated here. Neighbor-joining and the maximum parsimony methods were used in this study to take a look at the distribution of domains present in RnlA and RnlB proteins, among members of Gammaproteobacteria. Also, the possible roles of photodynamic therapy (PDT) in providing a substrate for better phage therapy are herein discussed.
ABSTRACT
Resistant infections essentially cause mortality in a burn unit. Several bacteria contribute to burn infections; among these, Pseudomonas aeruginosa majorly contributes to these infections revealing significant drug resistance. Similar to other bacteria, P. aeruginosa reveals various mechanisms to attain highest pathogenicity and resistance; among these, efflux pumps and quorum sensing are crucial. Quorum sensing enables effective communication between bacteria and synchronizes their gene expression resulting in optimum effect of the secreted proteins; alternatively, efflux pumps increase the bacterial resistance by pumping out the antimicrobial factors as well as the QS signals and precursors. Of recent, increasing episodes of drug resistance led to new findings and approaches for killing pathogenic bacteria without inducing the drug-resistant species. Photodynamic therapy (PDT), considered as an adjuvant and innovative method for conventional antibiotic therapy, is a photochemical reaction that includes visible light, oxygen, and a photosensitizer (PS). In this therapy, after exposure to visible light, the PS generates reactive oxygen species (ROS) that are bacteriostatic or bactericidal. Furthermore, this oxidative stress can disrupt the coordination of gene expression and alter the bacterial behavior. Considering the fact that the adaption and several gene expression patterns of microorganisms within the biofilm make them notably resistant to the recent antimicrobial treatments, this study aimed to emphasize the relationship between the efflux pump and QS under oxidative stress and their role in P. aeruginosa's reaction to PDT.
