The cryo-EM structure of the S-layer deinoxanthin-binding complex of Deinococcus radiodurans informs properties of its environmental interactions

In eukaryotes the bimetallic Cu/Zn superoxide dismutase (SOD) enzymes play important roles in biology of reactive oxygen species by disproportionating anion. Recently, we reported that fungal pathogen Candida albicans expresses a novel copper-only SOD, known as SOD5, lacks zinc cofactor and electrostatic loop (ESL) domain Cu/Zn-SODs for substrate guidance. Despite these abnormalities, C. SOD5 can disproportionate at rates limited only diffusion. Here demonstrate this curious SOD occurs throughout kingdom well phylogenetically distant oomycetes or “pseudofungi” species. It is form extracellular fungi oomycetes, stark contrast to plants animals. Through structural biochemical approaches SODs have evolved with specialized active site consisting two highly conserved residues equivalent Glu-110 Asp-113. The positions are binding ligands control catalysis copper lieu ESL. Similar ion Cu/Zn-SODs, helps orient key copper-coordinating histidine extends pH range enzyme catalysis. Asp-113 connects manner similar ESL assists binding. Copper-only virulence factors certain pathogens; thus unique may be target future anti-fungal strategies.