Okumura Masaki, Inoue Shin-Ichiro, Kuwata Keiko, Kinoshita Toshinori
Division of Biological Science, Graduate School of Science (M.O., S.I., T.K.), and Institute of Transformative Bio-Molecules (K.K., T.K.), Nagoya University, Chikusa, Nagoya 464-8602, Japan.
Division of Biological Science, Graduate School of Science (M.O., S.I., T.K.), and Institute of Transformative Bio-Molecules (K.K., T.K.), Nagoya University, Chikusa, Nagoya 464-8602, Japan
Plant Physiol. 2016 May;171(1):580-9. doi: 10.1104/pp.16.00355. Epub 2016 Mar 25.
Plant plasma membrane H(+)-ATPase acts as a primary transporter via proton pumping and regulates diverse physiological responses by controlling secondary solute transport, pH homeostasis, and membrane potential. Phosphorylation of the penultimate threonine and the subsequent binding of 14-3-3 proteins in the carboxyl terminus of the enzyme are required for H(+)-ATPase activation. We showed previously that photosynthesis induces phosphorylation of the penultimate threonine in the nonvascular bryophyte Marchantia polymorpha However, (1) whether this response is conserved in vascular plants and (2) the process by which photosynthesis regulates H(+)-ATPase phosphorylation at the plasma membrane remain unresolved issues. Here, we report that photosynthesis induced the phosphorylation and activation of H(+)-ATPase in Arabidopsis (Arabidopsis thaliana) leaves via sugar accumulation. Light reversibly phosphorylated leaf H(+)-ATPase, and this process was inhibited by pharmacological and genetic suppression of photosynthesis. Immunohistochemical and biochemical analyses indicated that light-induced phosphorylation of H(+)-ATPase occurred autonomously in mesophyll cells. We also show that the phosphorylation status of H(+)-ATPase and photosynthetic sugar accumulation in leaves were positively correlated and that sugar treatment promoted phosphorylation. Furthermore, light-induced phosphorylation of H(+)-ATPase was strongly suppressed in a double mutant defective in ADP-glucose pyrophosphorylase and triose phosphate/phosphate translocator (adg1-1 tpt-2); these mutations strongly inhibited endogenous sugar accumulation. Overall, we show that photosynthesis activated H(+)-ATPase via sugar production in the mesophyll cells of vascular plants. Our work provides new insight into signaling from chloroplasts to the plasma membrane ion transport mechanism.
植物质膜H(+)-ATP酶通过质子泵作用作为一种初级转运体，并通过控制次级溶质转运、pH稳态和膜电位来调节多种生理反应。该酶羧基末端倒数第二个苏氨酸的磷酸化以及随后14-3-3蛋白的结合是H(+)-ATP酶激活所必需的。我们之前表明光合作用会诱导非维管苔藓植物地钱中倒数第二个苏氨酸的磷酸化。然而，（1）这种反应在维管植物中是否保守，以及（2）光合作用调节质膜上H(+)-ATP酶磷酸化的过程仍然是未解决的问题。在这里，我们报告光合作用通过糖积累诱导拟南芥叶片中H(+)-ATP酶的磷酸化和激活。光可逆地使叶片H(+)-ATP酶磷酸化，并且这个过程被光合作用的药理学和遗传学抑制所抑制。免疫组织化学和生化分析表明，光诱导的H(+)-ATP酶磷酸化在叶肉细胞中自主发生。我们还表明，叶片中H(+)-ATP酶的磷酸化状态与光合糖积累呈正相关，并且糖处理促进磷酸化。此外，在ADP-葡萄糖焦磷酸化酶和磷酸丙糖/磷酸转运体双突变体（adg1-1 tpt-2）中，光诱导的H(+)-ATP酶磷酸化受到强烈抑制；这些突变强烈抑制内源性糖积累。总体而言，我们表明光合作用通过维管植物叶肉细胞中的糖产生激活H(+)-ATP酶。我们的工作为从叶绿体到质膜离子转运机制的信号传导提供了新的见解。
