Poster: Oxidative stress

Abs # 94: Copper chaperone for superoxide dismutase modulates the activity and protein stability of CuZnSODs in Arabidopsis thaliana

Presenter:	Chu, Chiung-Chih , d87226002@ntu.edu.tw
Authors	Chu, Chiung-Chih  (A) (B)  Jinn, Tsung-Luo  (A) (B)
Affiliations:	(A): Institute of plant Biology, National Taiwan University (B): National Taiwan University, 106 Taipei, Taiwan

The copper chaperone for superoxide dismutase (CCS) has been identified as a key factor to mediate copper into CuZn superoxide dismutase (CuZnSOD) in yeast and human. In Arabidopsis, there are three CuZnSODs genes (i.e. CSD1, CSD2 and CSD3 localized in the cytosol, chloroplast and peroxisome, respectively), but with only one CCS gene. In CCS knockout mutant, no CuZnSODs activity and reduced protein amount of CuZnSODs were found as compared to that of the wild type. The full-length cDNA clone of CCS predicted by computer was expressed in this CCS knockout background only CSD1 and CSD3 activity were recovered but not CSD2. We hypothesized that the recovery of the chloroplast localized CSD2 activity with this CCS clone should have a leader sequences extending to its 5' end, which was not predicted by computer. Genomic sequences search shown it indeed had another ATG start codon. Meanwhile the functional domain study of CCS was carried out by overexpression of domain II and III in CCS knockout mutant, but this was not able to restore CuZnSODs activity. In this study, we demonstrated that CCS not only modulates CuZnSODs activity but also the protein stability; the domain I in CCS may be necessary for its chaperone function in Arabidopsis.