Role of Mycobacterium tuberculosis copper-zinc superoxide dismutase

Superoxide dismutases (SODs) play an important role in protection against o xidative stress and have been shown to contribute to the pathogenicity of m any bacterial species. To determine the function of the mycobacterial coppe r and zinc-cofactored SOD (CuZnSOD), we constructed and characterized Mycob acterium tuberculosis and Mycobacterium bovis BCG CuZnSOD null mutants. Bot h strains were more sensitive to superoxides and hydrogen peroxide than wer e their respective parental strains. The survival of M. bovis BCG in unstim ulated as well as activated mouse bone marrow-derived macrophages was not a ffected by the loss of CuZnSOD. The survival of CuZnSOD deficient-M. tuberc ulosis in guinea pig tissues was comparable to that of its parental strain. These results indicate that the mycobacterial CuZnSOD is not essential for intracellular growth within macrophages and does not detectably contribute to the pathogenicity of M. tuberculosis.