Anaerobic microbes: Oxygen detoxification without superoxide dismutase

Superoxide reductase from the hyperthermophilic anaerobe Pyrococcus furiosu s uses electrons from reduced nicotinamide adenine dinucleotide phosphate, by way of rubredoxin and an oxidoreductase, to reduce superoxide to hydroge n peroxide, which is then reduced to water by peroxidases. Unlike superoxid e dismutase, the enzyme that protects aerobes from the toxic effects of oxy gen, SOR does not catalyze the production of oxygen from superoxide and the refore confers a selective advantage on anaerobes. Superoxide reductase and associated proteins are catalytically active 80 degrees C below the optimu m growth temperature (100 degrees C) of P. furiosus, conditions under which the organism is likely to be exposed to oxygen.