A Copper Chaperone for Superoxide Dismutase Confers Three Types of CuZnSOD Activity in Arabidopsis thaliana
Date Issued
2005
Date
2005
Author(s)
Chu, Chiung-Chih
DOI
en-US
Abstract
The copper chaperone for superoxide dismutase (CCS) has been identified as a key factor integrating copper into copper/zinc superoxide dismutase (CuZnSOD) in Saccharomyces cerevisiae and mammals. In 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 and a C-terminal domains. The ATX1-like and the 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 (TAIR) 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 (MIPS), 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.
The mature peptide of a putative CCS homologue in Oryza sativa (OsCCS) was ectopically expressed in the Atccs mutant and complemented the cytosolic and peroxisomal CuZnSOD activities. The results indicate that the OsCCS protein functions as a copper chaperone donating copper ions to CuZnSOD. The Atccs mutant can serve as another system, in addition to the yeast lys7 mutant, to confirm the function of the other CCS homologues of plants.
Subjects
銅鑲嵌蛋白質
超氧歧化酵素
阿拉伯芥
Copper Chaperone for Superoxide Dismutase
CuZnSOD
Arabidopsis thaliana
Type
other
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