The Bacteroides fragilis transcriptome response to oxygen and H2O2: the role of OxyR and its effect on survival and virulence.
The intestinal anaerobic symbiont, Bacteroides fragilis, is highly aerotolerant and resistant to H(2)O(2). Analysis of the transcriptome showed that expression of 45% of the genome was significantly affected by oxidative stress. The gene expression patterns suggested that exposure to oxidative stress induced an acute response to rapidly minimize the immediate effects of reactive oxygen species, then upon extended exposure a broad metabolic response was induced. This metabolic response induced genes encoding enzymes that can supply reducing power for detoxification and restore energy-generating capacity. An integral aspect of the metabolic response was downregulation of genes related to translation and biosynthesis which correlated with decreased growth and entry into a stationary phase-like growth state. Examination of oxyR mutants showed that they were impaired for the acute response and they induced the expanded metabolic response with only minimal exposure to stress. The oxyR mutants were more sensitive to oxidants in vitro and in vivo they were attenuated in an intra-abdominal abscess infection model. Aerotolerance and resistance to oxidative stress are physiological adaptations of B. fragilis to its environment that enhance survival in extra-intestinal sites and promote opportunistic infections.
Department of Microbiology and Immunology, East Carolina University, Brody School of Medicine, Greenville, NC 27834, USA.
Christian J
CJ
Sund
Edson R
ER
Rocha
Arthur O
AO
Tzianabos
Arthur O
AO
Tzinabos
W Greg
WG
Wells
Jason M
JM
Gee
Michael A
MA
Reott
Dorcas P
DP
O'Rourke
C Jeffrey
CJ
Smith
D000332:Aerobiosis; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001441:Bacteroides fragilis / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity / Q000502:physiology*; D004798:Enzymes / Q000378:metabolism; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008658:Inactivation, Metabolic; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D050296:Microbial Viability; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014774:Virulence
D001426:Bacterial Proteins; D004798:Enzymes; D017382:Reactive Oxygen Species; D014157:Transcription Factors; D006861:Hydrogen Peroxide