College of Life Science, University of the Chinese Academy of Sciences, Beijing, China.
Shenzhen Key Laboratory of Marine Bioresource and Eco-environmental Science, Guangdong Engineering Research Center for Marine Algal Biotechnology, College of Life Science and Oceanography, Shenzhen University, Shenzhen, China.
Plant Cell Rep. 2018 Sep;37(9):1343-1352. doi: 10.1007/s00299-018-2316-3. Epub 2018 Jun 23.
Cysteine in the N-terminal metal-binding domain (N-MBD) of TaHMA2 participates in Zn/Cd binding and translocation in Arabidopsis. Wheat heavy metal ATPase 2 (TaHMA2) can transport Zn and Cd across membranes. A previous study showed that cysteine (Cys) and glutamate residues in the N-terminal metal-binding domain (N-MBD) were necessary for metal-binding and translocation of TaHMA2 in yeast. However, the function of TaHMA2 in plants was not fully revealed. In this study, we investigated the roles of the CCxxE and CPC motifs in the N-MBD and the N/C-terminal regions of TaHMA2 in Zn/Cd translocation in root and shoot of Arabidopsis. Compared with the wild type, overexpression of TaHMA2 and the TaHMA2 derivative (glutamic substituted for alanine from CCxxE) in Arabidopsis increased root length, fresh weight and enhanced Zn/Cd root-to-shoot translocation. The plants with a truncated N/C-terminal of TaHMA2 were impaired in Zn/Cd tolerance and translocation, while mutagenesis of Cys in the N-MBD reduced the tolerance and transport activity of TaHMA2, suggesting the involvement of Cys in Zn/Cd binding and translocation in Arabidopsis. This study therefore provides a theoretical possibility for the application of TaHMA2 in transgenic breeding to regulate metal element balance in crop plants.
拟南芥 TaHMA2 的 N 端金属结合域（N-MBD）中的半胱氨酸参与 Zn/Cd 的结合和转运。小麦重金属 ATP 酶 2（TaHMA2）可以跨膜运输 Zn 和 Cd。先前的研究表明，N 端金属结合域（N-MBD）中的半胱氨酸（Cys）和谷氨酸残基对于 TaHMA2 在酵母中的金属结合和转运是必需的。然而，TaHMA2 在植物中的功能尚未完全揭示。在本研究中，我们研究了 N-MBD 中的 CCxxE 和 CPC 基序以及 TaHMA2 的 N/C 端区域在拟南芥根和地上部 Zn/Cd 转运中的作用。与野生型相比，拟南芥中 TaHMA2 和 TaHMA2 衍生物（CCxxE 中的丙氨酸被谷氨酸取代）的过表达增加了根长、鲜重，并增强了 Zn/Cd 从根到地上部的转运。截短 TaHMA2 的 N/C 端的植物在 Zn/Cd 耐受性和转运方面受损，而 N-MBD 中 Cys 的突变降低了 TaHMA2 的耐受性和转运活性，表明 Cys 参与了 Zn/Cd 在拟南芥中的结合和转运。因此，本研究为 TaHMA2 在转基因育种中的应用提供了理论可能性，以调节作物中金属元素的平衡。
