Original Paper

JBIC Journal of Biological Inorganic Chemistry

, Volume 18, Issue 8, pp 985-992

Yeast copper–zinc superoxide dismutase can be activated in the absence of its copper chaperone

  • Kevin W. SeaAffiliated withDepartment of Chemistry and Biochemistry, University of CaliforniaDepartment of Chemistry, Pomona College Email author 
  • , Yuewei ShengAffiliated withDepartment of Chemistry and Biochemistry, University of California
  • , Herman L. LelieAffiliated withDepartment of Chemistry and Biochemistry, University of CaliforniaBruin Biometrics LLC
  • , Lindsay Kane BarneseAffiliated withDepartment of Chemistry and Biochemistry, University of CaliforniaConcordia University
  • , Armando DurazoAffiliated withDepartment of Chemistry and Biochemistry, University of CaliforniaDepartment of Chemical and Environmental Engineering, University of Arizona
  • , Joan Selverstone ValentineAffiliated withDepartment of Chemistry and Biochemistry, University of CaliforniaDepartment of Bioinspired Science, Ewha Womans University
  • , Edith Butler GrallaAffiliated withDepartment of Chemistry and Biochemistry, University of California

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Abstract

Copper–zinc superoxide dismutase (Sod1) is an abundant intracellular enzyme that catalyzes the disproportionation of superoxide to give hydrogen peroxide and dioxygen. In most organisms, Sod1 acquires copper by a combination of two pathways, one dependent on the copper chaperone for Sod1 (CCS), and the other independent of CCS. Examples have been reported of two exceptions: Saccharomyces cerevisiae, in which Sod1 appeared to be fully dependent on CCS, and Caenorhabditis elegans, in which Sod1 was completely independent of CCS. Here, however, using overexpressed Sod1, we show there is also a significant amount of CCS-independent activation of S. cerevisiae Sod1, even in low-copper medium. In addition, we show CCS-independent oxidation of the disulfide bond in S. cerevisiae Sod1. There appears to be a continuum between CCS-dependent and CCS-independent activation of Sod1, with yeast falling near but not at the CCS-dependent end.

Keywords

Disulfide bond Sod1 Copper chaperone CCS1 Copper transport