Inventory and functional characterization of the HAK potassium transporters of rice
Inventory and functional characterization of the HAK potassium transporters of rice
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DOI：
10.1104/pp.007781
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发表时间：
2002-10-01
期刊：
影响因子：
7.4
通讯作者：
Rodríguez-Navarro, A
中科院分区：
文献类型：
--
作者：
Bañuelos, MA;Garciadeblas, B;Rodríguez-Navarro, A
植物从土壤溶液中吸收大量的K+，并将其分配给所有器官的细胞，在那里它实现重要的生理功能。K+从土壤溶液中转运到其最终目的地是由通道和转运蛋白介导的。为了更好地了解K+在植物中的运动，我们打算在水稻（Oryza sativa cv Nipponbare）中描述大的KT-HAK-KUP转运蛋白家族的功能。通过数据库检索和cDNA克隆，我们鉴定了17个编码该家族转运蛋白的基因（OsHAK 1 -17），并获得了另外两个基因存在的证据。对编码的转运蛋白的系统发育分析揭示了它们之间的巨大多样性，并且三个远距离转运蛋白，OsHAK 1，OsHAK 7和OsHAK 10，在酵母（酿酒酵母）和细菌突变体中表达以确定它们的功能。这三种转运蛋白介导K+流入或流出，这取决于实验条件。对酵母和K+饥饿水稻幼苗根系中HAK介导的K+内流的比较动力学分析表明，HAK转运蛋白参与了根系K+吸收。我们讨论了所有的HAK转运蛋白都可能介导K+的转运，但可能不仅仅是在质膜上。OSHAK 10-绿色荧光蛋白融合蛋白在活洋葱表皮细胞中的瞬时表达将该蛋白质靶向到液泡膜。
Plants take up large amounts of K+ from the soil solution and distribute it to the cells of all organs, where it fulfills important physiological functions. Transport of K+ from the soil solution to its final destination is mediated by channels and transporters. To better understand K+ movements in plants, we intended to characterize the function of the large KT-HAK-KUP family of transporters in rice (Oryza saliva cv Nipponbare). By searching in databases and cDNA cloning, we have identified 17 genes (OsHAK1-17) encoding transporters of this family and obtained evidence of the existence of other two genes. Phylogenetic analysis of the encoded transporters reveals a great diversity among them, and three distant transporters, OSHAK1, OsHAK7, and OsHAK10, were expressed in yeast (Saccharomyces cerevisiae) and bacterial mutants to determine their functions. The three transporters mediate K+ influxes or effluxes, depending on the conditions of the experiment. A comparative kinetic analysis of HAK-mediated K+ influx in yeast and in roots of K+-starved rice seedlings demonstrated the involvement of HAK transporters in root K+ uptake. We discuss that all HAK transporters may mediate K+ transport, but probably not only in the plasma membrane. Transient expression of the OSHAK10-green fluorescent protein fusion protein in living onion epidermal cells targeted this protein to the tonoplast.