AtNHX5 and AtNHX6 Control Cellular K+ and pH Homeostasis in Arabidopsis: Three Conserved Acidic Residues Are Essential for K+ Transport.
AtNHX5 and AtNHX6 Control Cellular K+ and pH Homeostasis in Arabidopsis: Three Conserved Acidic Residues Are Essential for K+ Transport.
复制标题
DOI：
10.1371/journal.pone.0144716
复制
发表时间：
2015
期刊：
影响因子：
3.7
通讯作者：
Qiu QS
中科院分区：
文献类型：
--
作者：
Wang L;Wu X;Liu Y;Qiu QS
AtNHX5和AtNHX6是拟南芥内体Na+、K+/H+逆向转运蛋白，在植物生长发育中发挥着重要作用。然而，它们在 K+ 和 pH 稳态中的功能仍不清楚。在本报告中，我们描述了 AtNHX5 和 AtNHX6 在拟南芥 K+ 和 H+ 稳态中的功能。使用酵母表达系统，我们发现 AtNHX5 和 AtNHX6 恢复了对高 K+ 或盐的耐受性。我们进一步发现 AtNHX5 和 AtNHX6 在酸性 pH 条件下在高 K+ 下发挥作用，而 AtCHXs 在碱性条件下在低 K+ 下发挥作用。此外，我们还发现 nhx5 nhx6 双突变体含有较少的 K+，并且对低 K+ 处理敏感。 AtNHX5 或 AtNHX6 基因在 nhx5 nhx6 中的过表达使根生长恢复到野生型水平。 AtNHX5 中的三个保守酸性残基 D164、E188 和 D193 以及 AtNHX6 中的 D165、E189 和 D194 对于 K+ 稳态和植物生长至关重要。用荧光 pH 指示剂 BCECF 或半微电极测量，nhx5 nhx6 的液泡和细胞 pH 值降低。我们进一步表明 AtNHX5 和 AtNHX6 定位于高尔基体和 TGN。总的来说，AtNHX5 和 AtNHX6 在拟南芥中的 K+ 和 pH 稳态中发挥着重要作用。三个保守的酸性残基对于 K+ 转运至关重要。
AtNHX5 and AtNHX6, the endosomal Na+,K+/H+ antiporters in Arabidopsis, play an important role in plant growth and development. However, their function in K+ and pH homeostasis remains unclear. In this report, we characterized the function of AtNHX5 and AtNHX6 in K+ and H+ homeostasis in Arabidopsis. Using a yeast expression system, we found that AtNHX5 and AtNHX6 recovered tolerance to high K+ or salt. We further found that AtNHX5 and AtNHX6 functioned at high K+ at acidic pH while AtCHXs at low K+ under alkaline conditions. In addition, we showed that the nhx5 nhx6 double mutant contained less K+ and was sensitive to low K+ treatment. Overexpression of AtNHX5 or AtNHX6 gene in nhx5 nhx6 recovered root growth to the wild-type level. Three conserved acidic residues, D164, E188, and D193 in AtNHX5 and D165, E189, and D194 in AtNHX6, were essential for K+ homeostasis and plant growth. nhx5 nhx6 had a reduced vacuolar and cellular pH as measured with the fluorescent pH indicator BCECF or semimicroelectrode. We further show that AtNHX5 and AtNHX6 are localized to Golgi and TGN. Taken together, AtNHX5 and AtNHX6 play an important role in K+ and pH homeostasis in Arabidopsis. Three conserved acidic residues are essential for K+ transport.