Identification and functional characterization of cation-chloride cotransporters in plants
Identification and functional characterization of cation-chloride cotransporters in plants
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DOI：
10.1111/j.1365-313x.2007.03048.x
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发表时间：
2007-04-01
期刊：
影响因子：
7.2
通讯作者：
Talon, Manuel
中科院分区：
文献类型：
--
作者：
Colmenero-Flores, Jose M.;Martinez, German;Talon, Manuel
氯离子是植物体内必需的营养物质，也是植物组织中含量最丰富的无机阴离子之一。我们已经克隆了拟南芥编码阳离子-氯-共转运蛋白(CCC)家族成员的基因。推导出的植物CCC蛋白是高度保守的，系统发育分析揭示了它们与动物K+：CL-共转运蛋白亚家族的关系。在非洲爪哇卵母细胞中，非洲爪蛙CCC蛋白(At CCC)催化K+、Na+和Cl-的协同转运，这种转运活性被脊椎动物Na+：K+：CL-转运蛋白的特异性抑制剂布美塔尼德抑制，这表明At CCC编码一个真正的Na+：K+：CL-共转运蛋白。对转At CCC启动子-β-葡萄糖醛酸酶的拟南芥植株的分析表明，在根和地上部的维管组织中，木质部/共生体交界处、根尖、毛状体、叶海鞘、叶托叶和花药中都有优势表达。在CCC基因中插入两个独立T-DNA的纯合子植株表现出较短的器官，如花序茎、根、叶和角果。花序茎伸长带在抽穗过程中常出现坏死区，严重影响种子产量。此外，CCC植株在高盐度下表现出氯离子动态平衡的缺陷，因为它们在地上部和根中积累的Cl-量分别高于处理的野生型和低于处理的野生型，这表明CCC参与了长距离的Cl-运输。关于阳离子-氯离子共转运体在植物王国中的存在及其在主要植物发育过程和氯离子稳态中的重要作用，提供了令人信服的证据。
Chloride (Cl-) is an essential nutrient and one of the most abundant inorganic anions in plant tissues. We have cloned an Arabidopsis thaliana cDNA encoding for a member of the cation-Cl- cotransporter (CCC) family. Deduced plant CCC proteins are highly conserved, and phylogenetic analyses revealed their relationships to the sub-family of animal K+:Cl- cotransporters. In Xenopus laevis oocytes, the A. thaliana CCC protein (At CCC) catalysed the co-ordinated symport of K+, Na+ and Cl-, and this transport activity was inhibited by the 'loop' diuretic bumetanide, a specific inhibitor of vertebrate Na+:K+:Cl- cotransporters, indicating that At CCC encodes for a bona fide Na+:K+:Cl- cotransporter. Analysis of At CCC promoter-beta-glucuronidase transgenic Arabidopsis plants revealed preferential expression in the root and shoot vasculature at the xylem/symplast boundary, root tips, trichomes, leaf hydathodes, leaf stipules and anthers. Plants homozygous for two independent T-DNA insertions in the CCC gene exhibited shorter organs such as inflorescence stems, roots, leaves and siliques. The elongation zone of the inflorescence stem of ccc plants often necrosed during bolt emergence, while seed production was strongly impaired. In addition, ccc plants exhibited defective Cl- homeostasis under high salinity, as they accumulated higher and lower Cl- amounts in shoots and roots, respectively, than the treated wild type, suggesting At CCC involvement in long-distance Cl- transport. Compelling evidence is provided on the occurrence of cation-chloride cotransporters in the plant kingdom and their significant role in major plant developmental processes and Cl- homeostasis.