CemR atypical response regulator impacts energy conversion in Campylobacteria

Campylobacter jejuni and Arcobacter butzleri are microaerobic food-borne human gastrointestinal pathogens that mainly cause diarrhoeal disease. These related species of the Campylobacteria class face variable atmospheric environments during infection and transmission, ranging from nearly anaerobic to aerobic conditions. Thus, they need to adjust their metabolism and respiration to the changing oxygen concentrations of the colonisation sites. Our studies revealed that C. jejuni and A. butzleri lacking a Campylobacteria -specific regulatory protein, C. jejuni Cj1608 or a homologue A. butzleri Abu0127, are unable to reprogram tricarboxylic acid cycle or respiration pathways, respectively, to produce ATP efficiently and, in consequence, adjust growth to changing oxygen supply. Based on these and previous studies on the homologous protein HP1021 in Helicobacter pylori , we propose that these regulatory proteins, which we named Campylobacteria energy and metabolism regulators (CemR), play an important role in Campylobacteria metabolism and energy regulation, allowing bacteria to adapt to variable oxygen availability.