Chemical Warfare at the Microorganismal Level: A Closer Look at the Superoxide Dismutase Enzymes of Pathogens

Abstract

Superoxide anion radical is generated as a natural byproduct of aerobic metabolism, but is also produced as part of the oxidative burst of the innate immune response design to kill pathogens. In living systems, superoxide is largely managed through superoxide dismutases (SODs), families of metalloenzymes that use Fe, Mn, Ni or Cu cofactors to catalyze the disproportionation of superoxide to oxygen and hydrogen peroxide. Given the bursts of superoxide faced by microbial pathogens, it comes as no surprise that SOD enzymes play important roles in microbial survival and virulence. Interestingly, microbial SOD enzymes not only detoxify host superoxide, but may also participate in signaling pathways that involve reactive oxygen species derived from the microbe itself, particularly in the case of eukaryotic pathogens. In this review, we will discuss the chemistry of superoxide radicals and the role of diverse SOD metalloenzymes in bacterial, fungal, and protozoan pathogens. We will highlight the unique features of microbial SOD enzymes that have evolved to accommodate the harsh lifestyle at the host-pathogen interface. Lastly, we will discuss key non-SOD superoxide scavengers that specific pathogens employ for defense against host superoxide.

Antioxidant System and Biomolecules Alteration in Pisum sativum under Heavy Metal Stress and Possible Alleviation by 5-Aminolevulinic Acid

“…The enhanced SOD activity in the presence of the metal ions suggests the production of ROS. Moreover, the boosting of SOD activity in P. sativum might be attributed to the de novo synthesis of enzyme protein by the transcription of SOD genes through a superoxide-mediated transduction signal [36]. The present results show that the enhancement of SOD activity is in parallel with H 2 O 2 production in plant cells (Figure 1c or Figure 3b).…”

Redox Homeostasis and Metabolism in Cancer: A Complex Mechanism and Potential Targeted Therapeutics

“…Moreover, reproductive systems depend on ROS to facilitate fertilization and normal maturation [15][16][17] (Figure 2). In addition, ROS are important during host defenses, directly and indirectly contributing to the destruction of microorganisms [18][19][20][21][22] (Figure 2). Thus, the key roles of ROS in biological processes are cell signaling, biosynthetic processes, and host defense.…”

A Cytoplasmic Heme Sensor Illuminates the Impacts of Mitochondrial and Vacuolar Functions and Oxidative Stress on Heme-Iron Homeostasis in Cryptococcus neoformans

“…We also investigated the impact of ROS by expressing the heme sensor in deletion mutants lacking either the cytosolic superoxide dismutase (strain sod1 Δ hs ) or the mitochondrial superoxide dismutase (strain sod2 Δ hs ). Superoxide dismutases, as well as other antioxidant proteins (e.g., catalases, glutathione peroxidases, and peroxiredoxins), protect cellular components from ROS damage ( 61 , 62 ). We found that the sod1 Δ hs strain showed similar eGFP/mKATE2 fluorescence ratios to those of WT hs when exposed to hemin, and the sod2 Δ hs strain exhibited a reduction in the sensor response under the same conditions ( Fig.…”