A copper chaperone for superoxide dismutase that confers three types of copper/zinc superoxide dismutase activity in Arabidopsis.
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.
Chu
Chiung-Chih
CC
Department of Life Science and Institute of Plant Biology, National Taiwan University, Taipei.
Lee
Wen-Chi
WC
Guo
Wen-Yu
WY
Pan
Shu-Mei
SM
Chen
Lih-Jen
LJ
Li
Hsou-Min
HM
Jinn
Tsung-Luo
TL
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D003300:Copper / Q000378:metabolism*; D017353:Gene Deletion; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000378:metabolism; D030821:Plants, Genetically Modified; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D013482:Superoxide Dismutase / Q000145:classification / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism*
D029681:Arabidopsis Proteins; C500748:CCS protein, Arabidopsis; D018832:Molecular Chaperones; D003300:Copper; D013482:Superoxide Dismutase; D015032:Zinc