AUTHOR=Kim Jong-Chul , Oh Euna , Hwang Sunyoung , Ryu Sangryeol , Jeon Byeonghwa 

TITLE=Non-selective regulation of peroxide and superoxide resistance genes by PerR in Campylobacter jejuni

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00126

DOI=10.3389/fmicb.2015.00126

ISSN=1664-302X

ABSTRACT=<p><italic>Campylobacter jejuni</italic> is an important foodborne pathogen. The molecular mechanisms for the regulation of oxidative stress resistance have not yet been understood fully in this bacterium. In this study, we investigated how PerR (peroxide stress regulator) modulates the transcriptional regulation of both peroxide and superoxide resistance genes in <italic>C. jejuni</italic>, particularly under oxidative stress conditions. The transcriptional levels of <italic>ahpC</italic>, <italic>katA</italic>, and <italic>sodB</italic> were substantially increased by aeration and oxidant exposure. Interestingly, a <italic>perR</italic> mutation completely abrogated the transcriptional response of <italic>ahpC</italic>, <italic>katA</italic> and <italic>sodB</italic> to oxidants. Furthermore, we demonstrated that <italic>perR</italic> transcription was reduced by aeration and oxidant exposure. In contrast to the unique role of PerR homologs in peroxide stress regulation in other bacteria, <italic>C. jejuni</italic> PerR directly regulates the transcription of <italic>sodB</italic>, the most important gene in superoxide defense, as evidenced by the alteration of <italic>sodB</italic> transcription by the <italic>perR</italic> mutation and direct binding of rPerR to the <italic>sodB</italic> promoter. In addition, we also observed notable morphological changes in <italic>C. jejuni</italic> from spiral rods to cocoid morphology under aerobic conditions. Based on the intracellular ATP levels, <italic>C. jejuni</italic> entered a viable-but-non-culturable (VBNC) state under aerobic conditions. These findings clearly demonstrate that <italic>C. jejuni</italic> possesses a unique regulatory mechanism of oxidative stress defense that does not specifically distinguish between peroxide and superoxide defense, and PerR plays a pivotal role in this non-selective regulation of oxidative stress resistance in <italic>C. jejuni</italic>.</p>