The Copper Chaperone for Superoxide Dismutase

Delivering copper within plant cells

“…In yeast and humans, other trafficking pathways deliver copper to super oxide dismutase [34] and to the mitochondria [35]. Given the high degree to which the CCH/RANI pathway is con served among yeast, plants and animals, it is reasonable to assume that plants also contain homologs of the superoxide dismutase and mitochondrial delivery pathways.…”

Dynamic Regulation of Copper Uptake and Detoxification Genes in Saccharomyces cerevisiae

“…Since our experiments demonstrate that Cup1 protein stably accumulates over the time course of these experiments, one mechanism may be that Cup1p itself outcompetes Ace1p for available Cu ions, either through competition for available free intracellular copper or through the disassembly of the tetracopper cluster in the Ace1p DNA binding domain that is essential for an active DNA binding configuration. It is interesting that proteins called Cu chaperones which deliver Cu ions to specific intracellular targets that include the secretory compartment, Cu,Zn superoxide dismutase, and the mitochondria have been identified in yeast and human cells (8,15,31). Therefore, it is possible that Cu ion chaperones exist to disassemble preformed Cu clusters or that the assembly reaction carried out by a Cu-specific chaperone is also reversible.…”

“…Elegant genetic screens have identified genes that are responsible for Cu uptake under nutritional conditions when essential levels of Cu ions are present in the cell (10,25), distribution to appropriate subcellular compartments (8,15,31,49), and detoxification under toxic conditions when Cu ions are present in excess (7,40,41,45). At the nutritional level, Cu uptake into yeast cells is mediated by two membrane-associated high-affinity Cu(I) transporters, encoded by CTR1 and CTR3 (10,25), and a cell surface Cu(II)/Fe(III) reductase, encoded by the FRE1 gene, which reduces Cu(II) to Cu(I) prior to uptake (14,21).…”

AtCCS is a functional homolog of the yeast copper chaperone Ccs1/Lys7

“…In yeast, Ccs1p/Lys7p delivers copper to the Cu/ZnSOD (Sod1p) by a direct protein-protein interaction [11,12], a function which is required to maintain the activity of reactive oxygen species sensitive enzymes involved in lysine and methionine biosynthesis [13]. Since chloroplasts are a site of oxygen production it is of interest to note that O 2 and the copper chaperone for Cu/Zn superoxide dismutase (CCS) regulate posttranslational activation of Cu/ZnSOD enzymes [14] by mediating correct disulfide formation [15].…”