The recA operon: A novel stress response gene cluster in Bacteroides fragilis.
Bacteroides fragilis, an opportunistic pathogen of humans, is a leading cause of bacteraemias and anaerobic abscesses which are often treated with metronidazole, a drug which damages DNA. This study investigated the responses of the B. fragilis recA three gene operon to the stress experienced during metronidazole treatment and exposure to reactive oxygen species simulating those generated by the host immune system during infection. A transcriptionally regulated response was observed using quantitative RT-PCR after metronidazole and hydrogen peroxide treatment, with all three genes being upregulated under stress conditions. In vivo and in vitro analysis of the functional role of the second gene of the operon was done using heterologous complementation and protein expression (in Escherichia coli), with subsequent biochemical assay. This gene encoded a functional bacterioferritin co-migratory protein (BCP) which was thiol-specific and had antioxidant properties, including protection of the glutamine synthetase III enzyme. This in vitro data supports the hypothesis that the genes of the operon may be involved in protection of the bacteria from the oxidative burst during tissue invasion and may play a significant role in bacterial survival and metronidazole resistance during treatment of B. fragilis infections.
Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, Private Bag, 7701, South Africa.
Samantha A
SA
Nicholson
Department of Microbiology and Immunology, East Carolina University, Greenville, NC 27834, USA.
Darren
D
Smalley
Department of Microbiology and Immunology, East Carolina University, Greenville, NC 27834, USA.
C Jeffrey
CJ
Smith
Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, Private Bag, 7701, South Africa. Electronic address: valerie.abratt@uct.ac.za.
Valerie R
VR
Abratt
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001442:Bacteroides Infections / Q000382:microbiology; D001441:Bacteroides fragilis / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006801:Humans; D008795:Metronidazole / Q000494:pharmacology; D005810:Multigene Family; D009876:Operon; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological / Q000187:drug effects
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D008795:Metronidazole; D011938:Rec A Recombinases
Bacterioferritin co-migratory protein; Bacteroides fragilis; recA