Fungi and SOD5

2021 update

This post started in the Fall of 2020 when one of us had a little dog with a very bad resurgence of Valley Fever, aka Coccidiodomycosis. The little dog went back on Fluconazole and some carprofen for the “pain” a not so good vet insisted she was in. This same vet wanted to amputate the front right leg at the shoulder joint. The carprofen made the poor little dog woozy. She fell down half a flight of stairs and injured her back. We put her on some Mitosynergy Cu(I)NA2 and hemp oil on top of the Fluconazole.

Last Fall the little dog could not use her right front leg due to joint damage to the shoulder. This was before the Valley fever went away and came back with a vengeance. She can now use all four legs to walk. Was it the Fluconazole, the copper, the hemp oil, or a combination? This post explores how copper is handled by some select fungi. Please feel free to share this post with your pet’s veterinarian. Do not under any circumstance use this post to play games with your pet’s health without a veterinarian’s assistance! Coccidiodomycosis can kill your pet! Some vets say that a dog must be on Fluconazole for life if there is joint damage no matter how low the antibody titers.

Back to the original post

Unlike mammalian SOD1 and SOD3, The Candida albicans SOD5 only binds copper and is a monomer rather than a dimer [1]. In addition, the copper site of SOD5 is solvent accessible. This will become important keeping copper that enters the mammalian body reserved for our SOD rather than that of a pathogenic yeast or fungi. Peterson and coworkers found that SOD5’s activity decreased above pH 7.5. [1]. these authors were also concerned with how key amino acids controlled this pH dependency. They were also concerned with how the pH of the growth of the medium controlled expression of SOD5. Duplicate experiments in Figure 1 show that that SOD5 expressed at pH 3.3 is slightly more active than that expressed at pH 7.5. Glycosylation, attachment of polymeric sugar residues is also more robust at pH 7.5. Anionic proteins in native gels migrate to the negatively charged anode. The addition of sugar residues in the form of glycosylation increases their migration towards the bottom of the gel. Note that the enzyme assays in the native blue tetrazolium gels was performed with full glyosylation, i.e. no EndoH to remove the sugars.

Fig. 1 Top left SOD5 activity as a function of growth conditions. Experiments were presumably preformed in duplicate. Numbers under the gels represent relative intensity of the white bands. Bottom Left Immunoblots with and without ENdoH enzyme treatment to remove glycosylation. Right SOD acitivity is detected by generation of supreoxide by exposing riboflavin to light. Superoxide, O2-, is generated by this reaction. O2 reacts with nitro blue tetrazolium to form a purple precipitate in the gel.

SOD5 to escape host super oxide attack

Candida albicans lacking SOD5, but not SOD6, are more susceptible to superoxide induced killing by co-culture with bone marrow derived macrophage (BMDM). [2] Unlike mammalian Cu/Zn SOD 1/2, SOD5 is not loaded with copper by chaperones, it acquires copper from the host’s extracellular spaces. [3]. This particular reference goes into structural aspects of an intra chain disulfide bond. Intra chain disulfide bonds can make a protein more compact such that they appear to run faster in a gel.

Fig. 2 A General mechanism by which SOD5 protects C albicans from host superoxide attack [3] B From reference [3] SOD5 acquires copper from the extracellular environment for activity. Zince has no effect on activity. An intrachain disulfide bond may be reduced (red) or oxidized (ox)

Because SOD5 is loaded with copper from extracellular spaces of the host, that is to say blood, it makes sense that chelators may be used to remove this copper [4]. The ideal chelator will remove copper from SOD5 but not Cu/Zn SOD1/3. Mitosynergy has a different and more natural strategy. Mitosynergy is of the opinion that copper in the +1 oxidation state will be absorbed differently than copper in the +2 oxidation state. Proper absorption is predicted to fuel host Cu/Zn SOD 1/3 while leaving yeast SOD5 starved for copper.


  1. Peterson RL, Galaleldeen A, Villarreal J, Taylor AB, Cabelli DE, Hart PJ, Culotta VC.(2016) The Phylogeny and Active Site Design of Eukaryotic Copper-only Superoxide Dismutases. J Biol Chem. 2016 Sep 30;291(40):20911-20923. [PMC free article]
  2. Gleason J. E., Galaleldeen A., Peterson R. L., Taylor A. B., Holloway S. P., Waninger-Saroni J., Cormack B. P., Cabelli D. E., Hart P. J., and Culotta V. C. (2014) Candida albicans SOD5 represents the prototype of an unprecedented class of Cu-only superoxide dismutases required for pathogen defense. Proc. Natl. Acad. Sci. U.S.A. 111, 5866–5871 10.1073/pnas.1400137111 [PMC free article]
  3. Frohner IE, Bourgeois C, Yatsyk K, Majer O, Kuchler K.(2009) Candida albicans cell surface superoxide dismutases degrade host-derived reactive oxygen species to escape innate immune surveillance. Frohner IE, Bourgeois C, Yatsyk K, Majer O, Kuchler K. Mol Microbiol. 2009 Jan;71(1):240-52. [PMC free article]
  4. Robinett NG, Culbertson EM, Peterson RL, Sanchez H, Andes DR, Nett JE, Culotta VC.(2019) Exploiting the vulnerable active site of a copper-only superoxide dismutase to disrupt fungal pathogenesis. J Biol Chem. 2019 Feb 22;294(8):2700-2713. [PMC free article]

Published by BL

I like to write educational websites

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