INTERRUPTION OF THE GPXA GENE INCREASES THE SENSITIVITY OF NEISSERIA-MENINGITIDIS TO PARAQUAT

Antioxidant enzymes are thought to be important for the survival of pa thogenic Neisseria species. We have further characterized the glutathi one peroxidase homolog gene (gpxA), which we recently isolated from Ne isseria meningitidis FAM20 (T. D. E, Moore and P. F. Sparling, Infect. Immun. 63:1603-1607, 1995). GpxA was found to be produced constitutiv ely in vivo. An isogenic, omega insertion mutant in the gpxA. gene was constructed and characterized. The gpxA insertion mutant was much mor e sensitive to the oxidative stress caused by paraquat and slightly mo re sensitive to hydrogen peroxide. This is the first demonstration of a phenotype arising from a mutation of a glutathione peroxidase homolo g gene in a prokaryotic organism. Protection of the cell by GpxA from the effects of oxidative stress caused by aerobic metabolism may contr ibute to the ability of Neisseria meningitidis to cause disease in the human host.