AUTHOR=Gundogdu Ozan , da Silva Daiani T. , Mohammad Banaz , Elmi Abdi , Wren Brendan W. , van Vliet Arnoud H. M. , Dorrell Nick 

TITLE=The Campylobacter jejuni Oxidative Stress Regulator RrpB Is Associated with a Genomic Hypervariable Region and Altered Oxidative Stress Resistance

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.02117

DOI=10.3389/fmicb.2016.02117

ISSN=1664-302X

ABSTRACT=<p><italic>Campylobacter jejuni</italic> is the leading cause of bacterial foodborne diarrhoeal disease worldwide. Despite the microaerophilic nature of the bacterium, <italic>C. jejuni</italic> can survive the atmospheric oxygen conditions in the environment. Bacteria that can survive either within a host or in the environment like <italic>C. jejuni</italic> require variable responses to survive the stresses associated with exposure to different levels of reactive oxygen species. The MarR-type transcriptional regulators RrpA and RrpB have recently been shown to play a role in controlling both the <italic>C. jejuni</italic> oxidative and aerobic stress responses. Analysis of 3,746 <italic>C. jejuni</italic> and 486 <italic>C. coli</italic> genome sequences showed that whilst <italic>rrpA</italic> is present in over 99% of <italic>C. jejuni</italic> strains, the presence of <italic>rrpB</italic> is restricted and appears to correlate with specific MLST clonal complexes (predominantly ST-21 and ST-61). <italic>C. coli</italic> strains in contrast lack both <italic>rrpA</italic> and <italic>rrpB</italic>. In <italic>C. jejuni rrpB</italic><sup>+</sup> strains, the <italic>rrpB</italic> gene is located within a variable genomic region containing the IF subtype of the type I Restriction-Modification (<italic>hsd</italic>) system, whilst this variable genomic region in <italic>C. jejuni rrpB</italic><sup>-</sup> strains contains the IAB subtype <italic>hsd</italic> system and not the <italic>rrpB</italic> gene. <italic>C. jejuni rrpB</italic><sup>-</sup> strains exhibit greater resistance to peroxide and aerobic stress than <italic>C. jejuni rrpB</italic><sup>+</sup> strains. Inactivation of <italic>rrpA</italic> resulted in increased sensitivity to peroxide stress in <italic>rrpB</italic><sup>+</sup> strains, but not in <italic>rrpB</italic><sup>-</sup> strains. Mutation of <italic>rrpA</italic> resulted in reduced killing of <italic>Galleria mellonella</italic> larvae and enhanced biofilm formation independent of <italic>rrpB</italic> status. The oxidative and aerobic stress responses of <italic>rrpB</italic><sup>-</sup> and <italic>rrpB</italic><sup>+</sup> strains suggest adaptation of <italic>C. jejuni</italic> within different hosts and niches that can be linked to specific MLST clonal complexes.</p>