Cu/Zn superoxide dismutase (SOD1) is a well-conserved anti-oxidant enzyme present in virtually all eukaryotic cells and tissues. While clearly important for oxidative stress, little is known about the biology of SODl under physiologically relevant oxygen conditions. The overall goal of this research is to understand how SOD1 is controlled by changes in cellular redox and how SOD1 and its activator protein CCS maintain cell fitness over a range of oxygen tensions. We identified CCS as the key activator of human SOD1 under atmospheric oxygen, but when oxygen levels drop, SODl is activated by a CCS independent pathway. We hypothesize this switch in SODl activation has evolved as adaptation to varying redox environments of tissues and sub-cellular compartments, and we will address this using both yeast and mammalian expression systems. We identified the SODl disulfide as the target for redox control of SOD], but how the disulfide is oxidized under hypoxic conditions without CCS is not clear. Yeast genetic screens will be used to identity the trans-acting factors that work independent of CCS to target the disulfide and activate SOD]. Cu/Zn SOD1 is not normally essential for aerobic life, but we observed that yeast sodl null mutants cannot thrive in air when levels of cytosolic phosphate rise. Phosphate-metal interactions may be key to this severe oxidative stress and through molecular/genetic approaches, we will explore the mechanism of phosphate mediated oxygen toxicity and how this damage is ameliorated by SOD1. Finally we observed an interesting effect of hypoxia on SODl and CCS. SODl activity and protein levels drop dramatically during hypoxia in yeast, while CCS levels remain high. We found that this hypoxic loss of SODl can be important for anaerobic cell survival. Hypoxia can trigger mitochondrial production of reactive oxygen and nitrogen species for signaling, and we will test the hypothesis that loss of mitochondrial SOD1 is a critical component of this hypoxic signaling. The rationale for maintaining CCS with low oxygen is not clear, but we observe an effect of CCS loss on genomic stability even under anaerobic conditions. We will continue to explore this novel effect of CCS on chromatin using molecular-genetic strategies. All together, these studies promise to shed new important light into the biology of an important anti-oxidant enzyme and its activator protein CCS.
A large number of human disorders Including diseases of the heart, lung and nervous systems have been attributed to damage from reactive oxygen. At the extreme opposite, low levels of oxygen or reactive oxygen are critical in vascular remodeling in cancer. SODl represents a major means for controling reactive oxygen. Hence, studies on the biology of S0D1 and CCS under a range of oxygen conditions are relevant.
|Gleason, Julie E; Li, Cissy X; Odeh, Hana M et al. (2014) Species-specific activation of Cu/Zn SOD by its CCS copper chaperone in the pathogenic yeast Candida albicans. J Biol Inorg Chem 19:595-603|
|Gleason, Julie E; Galaleldeen, Ahmad; Peterson, Ryan L et al. (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 111:5866-71|
|Baron, J Allen; Laws, Kaitlin M; Chen, Janice S et al. (2013) Superoxide triggers an acid burst in Saccharomyces cerevisiae to condition the environment of glucose-starved cells. J Biol Chem 288:4557-66|
|Aguirre, J Dafhne; Clark, Hillary M; McIlvin, Matthew et al. (2013) A manganese-rich environment supports superoxide dismutase activity in a Lyme disease pathogen, Borrelia burgdorferi. J Biol Chem 288:8468-78|
|Reddi, Amit R; Culotta, Valeria C (2013) SOD1 integrates signals from oxygen and glucose to repress respiration. Cell 152:224-35|
|Culotta, Valeria C; Daly, Michael J (2013) Manganese complexes: diverse metabolic routes to oxidative stress resistance in prokaryotes and yeast. Antioxid Redox Signal 19:933-44|
|Leitch, Jeffry M; Li, Cissy X; Baron, J Allen et al. (2012) Post-translational modification of Cu/Zn superoxide dismutase under anaerobic conditions. Biochemistry 51:677-85|
|Gross, Dominik P; Burgard, Caroline A; Reddehase, Silvia et al. (2011) Mitochondrial Ccs1 contains a structural disulfide bond crucial for the import of this unconventional substrate by the disulfide relay system. Mol Biol Cell 22:3758-67|
|Seetharaman, Sai V; Winkler, Duane D; Taylor, Alexander B et al. (2010) Disrupted zinc-binding sites in structures of pathogenic SOD1 variants D124V and H80R. Biochemistry 49:5714-25|
|McNaughton, Rebecca L; Reddi, Amit R; Clement, Matthew H S et al. (2010) Probing in vivo Mn2+ speciation and oxidative stress resistance in yeast cells with electron-nuclear double resonance spectroscopy. Proc Natl Acad Sci U S A 107:15335-9|
Showing the most recent 10 out of 48 publications