title: The impairment of methylmenaquinol:fumarate reductase affects hydrogen peroxide susceptibility and accumulation in Campylobacter jejuni.
abstract: The methylmenaquinol:fumarate reductase (Mfr) of Campylobacter jejuni is a periplasmic respiratory (redox) protein that contributes to the metabolism of fumarate and displays homology to succinate dehydrogenase (Sdh). Since chemically oxidized redox-enzymes, including fumarate reductase and Sdh, contribute to the generation of oxidative stress in Escherichia coli, we assessed the role of Mfr in C. jejuni after exposure to hydrogen peroxide (H2 O2 ). Our results show that a Mfr mutant (∆mfrA) strain was less susceptible to H2 O2 as compared to the wildtype (WT). Furthermore, the H2 O2 concentration in the ∆mfrA cultures was significantly higher than that of WT after exposure to the oxidant. In the presence of H2 O2 , catalase (KatA) activity and katA expression were significantly lower in the ∆mfrA strain as compared to the WT. Exposure to H2 O2 resulted in a significant decrease in total intracellular iron in the ∆mfrA strain as compared to WT, while the addition of iron to the growth medium mitigated H2 O2 susceptibility and accumulation in the mutant. The ∆mfrA strain was significantly more persistent in RAW macrophages as compared to the WT. Scanning electron microscopy showed that infection with the ∆mfrA strain caused prolonged changes to the macrophages' morphology, mainly resulting in spherical-shaped cells replete with budding structures and craters. Collectively, our results suggest a role for Mfr in maintaining iron homeostasis in H2 O2 stressed C. jejuni, probably via affecting the concentrations of intracellular iron.
authors: Food Animal Health Research Program, Ohio Agricultural Research and Development Center, Department of Veterinary Preventive Medicine, The Ohio State University, Wooster, Ohio.
authors: Issmat I
authors: II
authors: Kassem
authors: Mahesh
authors: M
authors: Khatri
authors: Yasser M
authors: YM
authors: Sanad
authors: Melinda
authors: M
authors: Wolboldt
authors: Yehia M
authors: YM
authors: Saif
authors: Jonathan W
authors: JW
authors: Olson
authors: Gireesh
authors: G
authors: Rajashekara
mesh_terms: D000818:Animals; D016123:Campylobacter jejuni / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D002460:Cell Line; D017353:Gene Deletion; D006861:Hydrogen Peroxide / Q000633:toxicity*; D007501:Iron / Q000378:metabolism*; D008264:Macrophages / Q000166:cytology / Q000382:microbiology; D051379:Mice; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D008855:Microscopy, Electron, Scanning; D013385:Succinate Dehydrogenase / Q000235:genetics / Q000378:metabolism*
chemical_list: D006861:Hydrogen Peroxide; D007501:Iron; D013385:Succinate Dehydrogenase
keywords: C. jejuni; Mfr; catalase; hydrogen peroxide resistance; iron; macrophage; methylmenaquinol:fumarate reductase