AtPHT4;4 is a chloroplast-localized ascorbate transporter in Arabidopsis.
AtPHT4;4 is a chloroplast-localized ascorbate transporter in Arabidopsis.
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DOI：
10.1038/ncomms6928
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发表时间：
2015-01-05
影响因子：
16.6
通讯作者：
Moriyama, Yoshinori
中科院分区：
文献类型：
--
作者：
Miyaji, Takaaki;Kuromori, Takashi;Takeuchi, Yu;Yamaji, Naoki;Yokosho, Kengo;Shimazawa, Atsushi;Sugimoto, Eriko;Omote, Hiroshi;Ma, Jian Feng;Shinozaki, Kazuo;Moriyama, Yoshinori
抗坏血酸是一种抗氧化剂和辅酶，在体内的各种代谢反应。在植物叶绿体中，需要高水平的抗坏血酸来克服强光引起的光抑制。然而，抗坏血酸是在线粒体中合成的，并且抗坏血酸转运到叶绿体中的分子机制尚不清楚。在这里，我们表明，AtPHT 4;4，拟南芥磷酸盐转运蛋白4家族的成员，作为抗坏血酸转运蛋白的功能。体外分析表明，含有纯化AtPHT 4;4蛋白的脂蛋白体表现出膜电位和Cl−依赖性的抗坏血酸摄取。AtPHT 4;4蛋白在叶绿体被膜中大量表达。AtPHT 4的敲除; 4导致叶中还原形式的抗坏血酸盐的水平降低，并且光合作用期间过量能量的热耗散过程受到损害。综上所述，这些观察结果表明AtPHT 4;4蛋白是叶绿体被膜上的抗坏血酸转运蛋白，这可能是耐受强光胁迫所必需的。 在植物中，抗坏血酸在线粒体中合成，但在叶绿体中作为抗氧化剂发挥重要作用。Miyaji等在此表明AtPHT 4;4是叶绿体被膜抗坏血酸转运蛋白，并表明它是光胁迫下消耗多余能量所必需的。
Ascorbate is an antioxidant and coenzyme for various metabolic reactions in vivo. In plant chloroplasts, high ascorbate levels are required to overcome photoinhibition caused by strong light. However, ascorbate is synthesized in the mitochondria and the molecular mechanisms underlying ascorbate transport into chloroplasts are unknown. Here we show that AtPHT4;4, a member of the phosphate transporter 4 family of Arabidopsis thaliana, functions as an ascorbate transporter. In vitro analysis shows that proteoliposomes containing the purified AtPHT4;4 protein exhibit membrane potential- and Cl−-dependent ascorbate uptake. The AtPHT4;4 protein is abundantly expressed in the chloroplast envelope membrane. Knockout of AtPHT4;4 results in decreased levels of the reduced form of ascorbate in the leaves and the heat dissipation process of excessive energy during photosynthesis is compromised. Taken together, these observations indicate that the AtPHT4;4 protein is an ascorbate transporter at the chloroplast envelope membrane, which may be required for tolerance to strong light stress. In plants, ascorbate is synthesized in the mitochondria yet plays essential roles as an antioxidant in the chloroplast. Here, Miyaji et al. show that AtPHT4;4 is a chloroplast envelope ascorbate transporter and suggest it is required for dissipation of excess energy under light stress.
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影响因子：
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通讯作者：
Moriyama, Yoshinori