A Copper Chaperone for Superoxide Dismutase That Confers Three Types of Copper/Zinc Superoxide Dismutase Activity in Arabidopsis

Abstract

The copper chaperone for superoxide dismutase (CCS) has been identified as a key factor integrating copper into copper/zinc superoxide dismutase (CuZnSOD) in yeast (Saccharomyces cerevisiae) and mammals. In Arabidopsis (Arabidopsis thaliana), only one putative CCS gene (AtCCS, At1g12520) has been identified. The predicted AtCCS polypeptide contains three distinct domains: a central domain, flanked by an ATX1-like domain, and a C-terminal domain. The ATX1-like and C-terminal domains contain putative copper-binding motifs. We have investigated the function of this putative AtCCS gene and shown that a cDNA encoding the open reading frame predicted by The Arabidopsis Information Resource complemented only the cytosolic and peroxisomal CuZnSOD activities in the Atccs knockout mutant, which has lost all CuZnSOD activities. However, a longer AtCCS cDNA, as predicted by the Munich Information Centre for Protein Sequences and encoding an extra 66 amino acids at the N terminus, could restore all three, including the chloroplastic CuZnSOD activities in the Atccs mutant. The extra 66 amino acids were shown to direct the import of AtCCS into chloroplasts. Our results indicated that one AtCCS gene was responsible for the activation of all three types of CuZnSOD activity. In addition, a truncated AtCCS, containing only the central and C-terminal domains without the ATX1-like domain failed to restore any CuZnSOD activity in the Atccs mutant. This result indicates that the ATX1-like domain is essential for the copper chaperone function of AtCCS in planta.

Metal Homeostasis in Cyanobacteria and Chloroplasts. Balancing Benefits and Risks to the Photosynthetic Apparatus

“…In Arabidopsis chloroplasts, two P-type ATPases function in the inner membrane and an additional P-type ATPase functions in the thylakoid membrane (AbdelGhany et al, 2005;Seigneurin-Berny et al, 2005). One chloroplast copper chaperone of the CCS family has been identified (Chu et al, 2005; Fig. 2).…”

“…Cu transport is carried out by the CtaA and PacS P-type ATPases in cyanobacteria (Tottey et al, 2005) and by PAA1, HMA1, and PAA2 in plants (Abdel-Ghany et al, 2005;Seigneurin-Berny et al, 2005). Intracellular Cu transport is carried out by the Atx1 in cyanobacteria and by the Cu chaperone for SOD (CCS) in plants (Chu et al, 2005;Tottey et al, 2005).…”

Chaperonin 20 might be an iron chaperone for superoxide dismutase in activating iron superoxide dismutase (FeSOD)

“…10 However, results of both native-PAGE and gel filtration analyses indicated no major signal shift of FSD1 after incubation with CPN20, even though the same treatments enhanced FSD1 activity. 10 Similarly, interactions between CCS and CuZnSOD were found with yeast two-hybridization 3,22 but not immunoprecipitation or native gel analysis. 21,23 Thus, the interaction between CPN20 and FSD1 could be transient, similar to with CCS and CuZnSODs, chaperonins and co-chaperonins.…”

“…1,2 In Arabidopsis thaliana, CuZnSOD activation involves two pathways: the CCS-dependent pathway, which requires Cu chaperone of SOD (CCS), and an alternative pathway that acts in the absence of CCS. [3][4][5][6] FeSODs are found in prokaryotes and plants but not in nonphotosynthetic bacteria and animals 7,8 and have an important role in plants. For instance, products of three FeSOD genes (FSD1, 2, 3) are found in Arabidopsis chloroplasts; FSD2 and FSD3 are essential for chloroplast development.…”

How do plants respond to copper deficiency?

“…2 Despite its physiological importance, excess copper is toxic for plants because of its potential participation in the Fenton reaction. To minimize the damage by excess copper and also respond to copper deficiency, higher plants have several strategies, including the regulation of copper uptake in root cells, 3 strict copper trafficking via P-type ATPases and copper chaperones [4][5][6][7][8][9] or regulation of the levels of copper proteins in response to a change in the metal availability. 10,11 In addition plants respond to copper deficiency by expressing the alternative iron proteins which complement the function of copper proteins.…”