4n3t | pdb_00004n3t
Candida albicans Superoxide Dismutase 5 (SOD5), Cu(I)
Structural highlights
Function[SOD5_CANAL] Superoxide dismutases serve to convert damaging superoxide radicals, a key form of ROS, to less damaging hydrogen peroxide that can be converted into water by catalase action. Degrades host-derived reactive oxygen species to escape innate immune surveillance. Involved in the occurrence of miconazole-tolerant persisters in biofilms. Persisters are cells that survive high doses of an antimicrobial agent.[1] [2] [3] Publication Abstract from PubMedThe human fungal pathogens Candida albicans and Histoplasma capsulatum have been reported to protect against the oxidative burst of host innate immune cells using a family of extracellular proteins with similarity to Cu/Zn superoxide dismutase 1 (SOD1). We report here that these molecules are widespread throughout fungi and deviate from canonical SOD1 at the primary, tertiary, and quaternary levels. The structure of C. albicans SOD5 reveals that although the beta-barrel of Cu/Zn SODs is largely preserved, SOD5 is a monomeric copper protein that lacks a zinc-binding site and is missing the electrostatic loop element proposed to promote catalysis through superoxide guidance. Without an electrostatic loop, the copper site of SOD5 is not recessed and is readily accessible to bulk solvent. Despite these structural deviations, SOD5 has the capacity to disproportionate superoxide with kinetics that approach diffusion limits, similar to those of canonical SOD1. In cultures of C. albicans, SOD5 is secreted in a disulfide-oxidized form and apo-pools of secreted SOD5 can readily capture extracellular copper for rapid induction of enzyme activity. We suggest that the unusual attributes of SOD5-like fungal proteins, including the absence of zinc and an open active site that readily captures extracellular copper, make these SODs well suited to meet challenges in zinc and copper availability at the host-pathogen interface. Candida albicans SOD5 represents the prototype of an unprecedented class of Cu-only superoxide dismutases required for pathogen defense.,Gleason JE, Galaleldeen A, Peterson RL, Taylor AB, Holloway SP, Waninger-Saroni J, Cormack BP, Cabelli DE, Hart PJ, Culotta VC Proc Natl Acad Sci U S A. 2014 Apr 22;111(16):5866-71. doi:, 10.1073/pnas.1400137111. Epub 2014 Apr 7. PMID:24711423[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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