Distribution, cloning, characterisation and mutagenesis of sodC, the gene encoding copper/zinc superoxide dismutase, a potential determinant of virulence, in Haemophilus ducreyi.

The sodC gene encoding the periplasmic enzyme copper/zinc superoxide dismutase (CuZnSOD) has been cloned from Haemophilus ducreyi, the causative agent of the genital ulcer disease, chancroid. Examination of a collection of diverse strains indicates that it is present throughout the species. Cloned sodC has been expressed in E. coli and shown to encode active enzyme. Insertional mutagenesis was used to construct a non-functional version of the gene. This has been transferred into the chromosome of the parent H. ducreyi strain by electroporation and homologous recombination, in preparation for studies of the role of this enzyme in the interactive biology of the organism with its host, perhaps in protecting bacteria from superoxide radicals and their reactive progeny generated by neutrophils in the context of host defence.