1School of Materials Science, Japan Advanced Institute of Science and Technology, 1–1 Asahidai, Nomi City, Ishikawa, 923–1292, Japan.
2Division of Molecular Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Kumamoto, 8620976, Japan.
3Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305–8573, Japan.
4Department of Environmental Bioengineering Laboratory, Graduate School of Pharmaceutical Sciences, Osaka University, 1–6 Yamada-oka, Suita, Osaka, 565–0871, Japan.
*Corresponding author: E-mail: takagi@jaist.ac.jp
Online published: 4 April, 2009.
Phytochelatins (PCs) are Cys-rich peptides, synthesized by PC synthase in response to heavy metal ions. The C-terminal Cys-rich region of the PC synthase has homology with functional domains of metallochaperone, metallothionein and thioredoxin. To test the possibility that the C-terminal Cys-rich region of PC synthase has a role in regulating PC synthesis, we introduced point mutations into the PC synthase, replacing Cys358, Cys359, Cys363 and Cys366 residues with Ala. The mutant PC synthase had a lower PC synthesis ability than the wild-type enzyme. Further, oxidative conditions severely damaged mutant PC synthase whilst the wild-type enzyme suffered less damage, suggesting that the Cys-rich region of PC synthase may play an important role in anti-oxidation activity. Although the C-terminal of PC synthase is not conserved, our studies support the possibility that this region performs several important biological functions.
phytochelatins, phytochelatin synthase, Arabidopsis thaliana, cadmium, heavy metals, cystein (Cys), C-terminal, antioxidant, toxicity
