Fig 1.
The family of SOD enzymes in microbial pathogens.
In a gram-negative bacteria such as E. coli (left), the Mn-SodA and Fe-SodA are intracellular/cytosolic where Mn and Fe metals ions are generally bioavailable. Cu is extruded into the periplasmic space, driving the evolution of Cu/Zn-containing SodC in this extra-cytosolic compartment. In eukaryotes (right), the mitochondria thought to evolve from a gram-negative bacteria exhibits the equivalent partitioning of a Mn-Sod2 to the mitochondrial matrix and Cu/Zn Sod1 to the mitochondrial IMS and cytosol. Some pathogenic microbes have acquired additional SODs (lined in red), including the highly stable prophage-derived SodC-F in pathogenic E. coli (left) and in Candida albicans (right), the cytosolic Mn-Sod3 as a backup for Cu/Zn Sod1, and the Cu-only extracellular Sod4, Sod5, and Sod6.
Fig 2.
Model for Cu-only fungal SOD5 at the macrophage–pathogen interface.
Activated macrophages may attack invading microbes with toxic levels of Cu and superoxide (O2-). With its open Cu site, Sod5 on the surface of the fungal pathogen may be able to capture this host Cu, fueling the SOD enzyme to remove the superoxide in counterattack.