Modulation of Toxin-Antitoxin System Rnl AB Type II in Phage-Resistant Gammaproteobacteria Surviving Photodynamic Treatment

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.

Antimicrobial Photodynamic Therapy: Latest Developments with a Focus on Combinatory Strategies

“…One study suggests that, following a PDT treatment, ROS damages can cause quorum sensing and virulence pathway alterations rendering micro-organisms more susceptible to other therapies. Among these, phagotherapy is known to be modulated by multiple virulence factors [443]. Another approach can consist of conjugating phages with PSs, in order to improve interaction/delivery of the latter into target microorganisms.…”

AtaT Improves the Stability of Pore-Forming Protein EspB by Acetylating Lysine 206 to Enhance Strain Virulence

“…Type II TA is the most deeply studied TA, and it is involved in a variety of cell physiological activities. Although the role of type II TAs in the formation of persister cells has been questioned in recent years ( Goormaghtigh et al, 2018a ; Pontes and Groisman, 2019 ; Rosendahl et al, 2020 ), other functions, such as growth diminution during stress, biofilm formation, and phage inhibition, are still widely recognized ( Wen et al, 2014 ; Sauert et al, 2016 ; Hosseini et al, 2019 ; Jurënas and Van Melderen, 2020 ; Song and Wood, 2020 ). In this work, we demonstrated that the type II toxins AtaT is involved in the virulence of EHEC, including strains colonization, inducing severe pathological injury and host inflammatory response.…”

Biological Functions of Type II Toxin-Antitoxin Systems in Bacteria

“…Therefore, the free toxins RnlA or LsoA degrade most of the T4 mRNAs at the late stage of the infection and inhibits dmd-negative T4 phage propagation [117,120,121]. Phylogenetic analysis identified that RnlA domain-containing proteins are also present in other Enterobacteriaceae species, including Klebsiella pneumoniae, Acinetobacter baumannii and Pseudomonas aeruginosa [122]. This suggests that the RnlA-RnlB TA system-mediated anti-phage activity is a common strategy for members of the Enterobacteriaceae family.…”