OVEREXPRESSION OF A HYDROGEN PEROXIDE-RESISTANT PERIPLASMIC CU,ZN SUPEROXIDE-DISMUTASE PROTECTS ESCHERICHIA-COLI FROM MACROPHAGE KILLING

We have studied the effect of H2O2 on the activity of the Escherichia coli Cu,ZnSOD showing that, unlike the bovine enzyme, this bacterial C u,ZnSOD is highly resistant to inactivation by hydrogen peroxide. In v iew of the key role played by oxygen radicals in bacterial killing by phagocytes, we have tested the ability of E. coli strains expressing d ifferent amounts of Cu,ZnSOD in the periplasmic space to survive the p hagocytic attack of activated macrophages. Overexpression of the enzym e effectively protected the bacterial cell from macrophage billing. Th e results obtained support the hypothesis that in pathogenic bacteria periplasmic Cu,ZnSOD may reduce the oxyradical damages induced by the respiratory burst and therefore be important in virulence. (C) 1998 Ac ademic Press.