Vibrio cholerae periplasmic superoxide dismutase: isolation of the gene and overexpression of the protein.

Superoxide dismutases are ubiquitous enzymes which play an important role in protecting cells against oxidative damage and which have also been shown to contribute to the pathogenicity of many bacterial species. Here we demonstrate that Vibrio cholerae, the causative agent of cholerae, expresses an active periplasmic Cu,Zn superoxide dismutase. Moreover, we have set up an expression system yielding large amounts of V. cholerae recombinant Cu,Zn superoxide dismutase in the periplasm of Escherichia coli and a procedure to obtain the enzyme in a highly purified form. Unlike the bovine enzyme, V. cholerae Cu,Zn superoxide dismutase has been proved to be highly resistant to inactivation by hydrogen peroxide. This property, which appears to be common to other bacterial enzymes of this class, might improve the ability of Cu,Zn superoxide dismutase to protect bacteria against the reactive oxygen species produced by phagocytes.