Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, The State Key Laboratory of Plant Cell and Chromosome Engineering, Beijing, 100101, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, National Center for Plant Gene Research (Beijing), Beijing, 100101, China.
Plant Cell Environ. 2014 Jul;37(7):1561-73. doi: 10.1111/pce.12263. Epub 2014 Jan 27.
Copper is an essential micronutrient for plant growth and development, and copper transporter plays a pivotal role for keeping copper homeostasis. However, little is known about copper transporters in wheat. Here, we report a novel copper transporter gene family, TaCT1, in common wheat. Three TaCT1 homoeologous genes were isolated and assigned to group 5 chromosomes. Each of the TaCT1 genes (TaCT1-5A, -5B or -5D) possesses 12 transmembrane domains. TaCT1 genes exhibited higher transcript levels in leaf than in root, culm and spikelet. Excess copper down-regulated the transcript levels of TaCT1 and copper deficiency-induced TaCT1 expression. Subcellular experiments localized the TaCT1 to the Golgi apparatus. Yeast expression experiments and virus-induced gene silencing analysis indicated that the TaCT1 functioned in copper transport. Site-directed mutagenesis demonstrated that three amino acid residues, Met(35), Met(38) and Cys(365), are required for TaCT1 function. Phylogenetic and functional analyses suggested that homologous genes shared high similarity with TaCT1 may exist exclusively in monocot plants. Our work reveals a novel wheat gene family encoding major facilitator superfamily (MFS)-type copper transporters, and provides evidence for their functional involvement in promoting copper uptake and keeping copper homeostasis in common wheat.
铜是植物生长和发育所必需的微量元素，而铜转运蛋白在维持铜的体内平衡方面起着关键作用。然而，关于小麦中的铜转运蛋白知之甚少。在这里，我们报道了普通小麦中一种新的铜转运蛋白基因家族 TaCT1。分离并鉴定了三个 TaCT1 同源基因，它们被分配到 5 号染色体组上。每个 TaCT1 基因（TaCT1-5A、-5B 或-5D）都具有 12 个跨膜结构域。TaCT1 基因在叶片中的转录水平高于根、茎和小穗。过量的铜会下调 TaCT1 的转录水平，而铜缺乏会诱导 TaCT1 的表达。亚细胞实验将 TaCT1 定位到高尔基体。酵母表达实验和病毒诱导的基因沉默分析表明，TaCT1 参与铜的运输。定点突变实验表明，三个氨基酸残基 Met(35)、Met(38)和 Cys(365)是 TaCT1 功能所必需的。系统发育和功能分析表明，与 TaCT1 具有高度相似性的同源基因可能仅存在于单子叶植物中。我们的工作揭示了一个新的编码主要易化因子超家族（MFS）-型铜转运蛋白的小麦基因家族，并为它们在促进普通小麦铜吸收和维持铜体内平衡方面的功能参与提供了证据。
