Superoxide Dismutase: A Key Enzyme for the Survival of Intracellular Pathogens in Host

Abstract

Superoxide dismutase (SOD) is a crucial enzyme required to maintain the redox potential of the cells. It plays a vital role in protecting normal cells from reactive oxygen species (ROS) produced during many intracellular pathogens infections. SOD removes excess superoxide radicals (O2−) by converting them to hydrogen peroxide (H2O2) and molecular oxygen (O2). Several superoxide dismutase enzymes have been identified based on the metal ion as a cofactor. Human SOD differs from the intracellular pathogens in having Cu/Zn and Mn as metal cofactors. However, SOD of intracellular pathogens such as Trypanosoma, Leishmania, Plasmodium, and Mycobacterium have iron (Fe) as metal cofactors. Iron Superoxide Dismutase (FeSOD) is an essential enzyme in these pathogens that neutralizes the free radical of oxygen (O−) and prevents the formation of Peroxynitrite anion (ONOO−), helping the pathogens escape from redox-based cytotoxic killing. Moreover, most intracellular bacteria hold MnSOD or FeSOD in their cytoplasm such as Salmonella and Staphylococcus, whereas periplasm of some pathogenic bacteria and fungi are also cofactors with Cu/Zn and identified as CuZnSOD. This chapter will review the various types SOD present in intracellular pathogens and their role in the survival of these pathogens inside their host niche.