In Silico Characterization of Toxin-Antitoxin Systems in Campylobacter Isolates Recovered from Food Sources and Sporadic Human Illness.

Bishoy Wadie,Mohamed A. Abdel-Fattah,Mohamed Elhadidy,Alshymaa Yousef,Tamer Z. Salem,Shaimaa F. Mouftah

doi:10.3390/genes12010072

Abstract

Campylobacter spp. represents the most common cause of gastroenteritis worldwide with the potential to cause serious sequelae. The ability of Campylobacter to survive stressful environmental conditions has been directly linked with food-borne illness. Toxin-antitoxin (TA) modules play an important role as defense systems against antimicrobial agents and are considered an invaluable strategy harnessed by bacterial pathogens to survive in stressful environments. Although TA modules have been extensively studied in model organisms such as Escherichia coli K12, the TA landscape in Campylobacter remains largely unexplored. Therefore, in this study, a comprehensive in silico screen of 111 Campylobacter (90 C. jejuni and 21 C. coli) isolates recovered from different food and clinical sources was performed. We identified 10 type II TA systems belonging to four TA families predicted in Campylobacter genomes. Furthermore, there was a significant association between the clonal population structure and distribution of TA modules; more specifically, most (12/13) of the Campylobacter isolates belonging to ST-21 isolates possess HicB-HicA TA modules. Finally, we observed a high degree of shared synteny among isolates bearing certain TA systems or even coexisting pairs of TA systems. Collectively, these findings provide useful insights about the distribution of TA modules in a heterogeneous pool of Campylobacter isolates from different sources, thus developing a better understanding regarding the mechanisms by which these pathogens survive stressful environmental conditions, which will further aid in the future designing of more targeted antimicrobials.

Highlights

Campylobacter is considered the most common bacterial pathogen responsible for human gastroenteritis worldwide [1]
The alignment quality for each toxinantitoxin across the isolates was assessed based on a scaled score that takes into account the alignment coverage
All of the toxin/antitoxin genes discussed hereafter belong to type II TA systems; we obtained hits for cjrA-RNA

Summary

Introduction

Campylobacter is considered the most common bacterial pathogen responsible for human gastroenteritis worldwide [1]. Several studies have focused on the identification and characterization of virulence factors in Campylobacter through which infection is mediated. These factors are primarily associated with the expression of genes involved in colonization, cell invasion, motility, and toxin production [3,4]. Such investigations have provided the research community with a better understanding to identify potential drug targets and to develop therapeutic interventions. Despite the considerable importance of dissecting the mechanisms by which the virulence factors drive the infectivity of Campylobacter, our understanding of how Campylobacter is defending itself against antimicrobials is still lacking

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Conclusion