Transcriptional regulation of hemO encoding heme oxygenase in Clostridium perfringens.

A Gram-positive anaerobic pathogen, Clostridium perfringens, causes clostridial myonecrosis or gas gangrene in humans by producing numerous extracellular toxins and enzymes that act in concert to degrade host tissues. The ability of infectious bacteria to acquire sufficient iron during infection is essential for the pathogen to cause disease. In the C. perfringens strain 13 genome, a heme oxygenase gene homologue (CPE0214, hemO) was found and its role was examined. The purified recombinant HemO protein showed heme oxygenase activity that can convert heme to biliverdin. hemO transcription was induced in response to extracellular hemin in a dose-dependent manner. The global two-component VirR/VirS regulatory system and its secondary regulator VR-RNA had positive regulatory effects on the transcription of hemO. These data indicate that heme oxygenase may play important roles in iron acquisition and cellular metabolism, and that the VirR/VirS-VR-RNA system is also involved in the regulation of cellular iron homeostasis, which might be important for the survival of C. perfringens in a human host.