Identification of the Vibrio vulnificus ahpCl gene and its influence on survival under oxidative stress and virulence.
Pathogens have evolved sophisticated mechanisms to survive oxidative stresses imposed by host defense systems, and the mechanisms are closely linked to their virulence. In the present study, ahpCl, a homologue of Escherichia coli ahpC encoding a peroxiredoxin, was identified among the Vibrio vulnificus genes specifically induced by exposure to H(2)O(2). In order to analyze the role of AhpCl in the pathogenesis of V. vulnificus, a mutant, in which the ahpCl gene was disrupted, was constructed by allelic exchanges. The ahpCl mutant was hypersusceptable to killing by reactive oxygen species (ROS) such as H(2)O(2) and t-BOOH, which is one of the most commonly used hydroperoxides in vitro. The purified AhpCl reduced H(2)O(2) in the presence of AhpF and NADH as a hydrogen donor, indicating that V. vulnificus AhpCl is a NADH-dependent peroxiredoxin and constitutes a peroxide reductase system with AhpF. Compared to wild type, the ahpCl mutant exhibited less cytotoxicity toward INT-407 epithelial cells in vitro and reduced virulence in a mouse model. In addition, the ahpCl mutant was significantly diminished in growth with INT-407 epithelial cells, reflecting that the ability of the mutant to grow, survive, and persist during infection is also impaired. Consequently, the combined results suggest that AhpCl and the capability of resistance to oxidative stresses contribute to the virulence of V. vulnificus by assuring growth and survival during infection.
National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology, Center for Agricultural Biomaterials, and Research Institute for Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea.
Woon Ki
WK
Baek
Hyun Sung
HS
Lee
Man Hwan
MH
Oh
Myung Jin
MJ
Koh
Kun-Soo
KS
Kim
Sang Ho
SH
Choi
D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D015169:Colony Count, Microbial; D004847:Epithelial Cells / Q000382:microbiology; D055786:Gene Knockout Techniques; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity; D051379:Mice; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability; D008969:Molecular Sequence Data; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D054464:Peroxiredoxins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism / Q000502:physiology*; D017382:Reactive Oxygen Species / Q000494:pharmacology; D016415:Sequence Alignment; D013312:Stress, Physiological; D014735:Vibrio Infections / Q000382:microbiology; D041261:Vibrio vulnificus / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity / Q000502:physiology*; D014774:Virulence
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D017382:Reactive Oxygen Species; D009243:NAD; D006861:Hydrogen Peroxide; D054464:Peroxiredoxins