Regulation of phytochelatin synthesis by zinc and cadmium in marine green alga,Dunaliella tertiolecta |
| |
Authors: | Tsuji Naoki Hirayanagi Nayumi Iwabe Osamu Namba Takashi Tagawa Mariko Miyamoto Shiho Miyasaka Hitoshi Takagi Masahiro Hirata Kazumasa Miyamoto Kazuhisa |
| |
Institution: | Environmental Bioengineering Laboratory, Graduate School of Pharmaceutical Sciences, Osaka University, Suita, Osaka 565-0871, Japan. |
| |
Abstract: | Although Cd(2+) is a more effective inducer of phytochelatin (PC) synthesis than Zn(2+) in higher plants, we have observed greater induction of PC synthesis by Zn(2+) than Cd(2+) in the marine green alga, Dunaliella tertiolecta. To elucidate this unique regulation of PC synthesis by Zn(2+), we investigated the effects of Zn(2+) and Cd(2+) on the activities of both phytochelatin synthase (PC synthase) and enzymes in the GSH biosynthetic pathway. PC synthase was more strongly activated by Cd(2+) than by Zn(2+), but the difference was not very big. On the other hand, gamma-glutamylcysteine synthetase (gamma-ECS) and glutathione synthetase (GS) were activated by both heavy metals, but their activities were higher in Zn-treated cells than in Cd-treated cells. Dose-dependent stimulation of intracellular reactive oxygen species (ROS) production was observed with Zn(2+), but not Cd(2+) treatment. These results suggest that Zn(2+) strongly promotes the synthesis of GSH through indirect activation of gamma-ECS and GS by stimulating ROS generation. This acceleration of the flux rate for GSH synthesis might mainly contribute to high level PC synthesis. |
| |
Keywords: | Dunaliella tertiolecta Phytochelatins Glutathione Zinc Cadmium Phytochelatin synthase γ-Glutamylcysteine synthetase Glutathione synthetase Reactive oxygen species |
本文献已被 ScienceDirect PubMed 等数据库收录! |
|