@article{d9aec58c4e87411991c1e79f0ca31e7e,
title = "AtPHT4;4 is a chloroplast-localized ascorbate transporter in Arabidopsis",
abstract = "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.",
author = "Takaaki Miyaji and Takashi Kuromori and Yu Takeuchi and Naoki Yamaji and Kengo Yokosho and Atsushi Shimazawa and Eriko Sugimoto and Hiroshi Omote and Ma, {Jian Feng} and Kazuo Shinozaki and Yoshinori Moriyama",
note = "Funding Information: We wish to thank Cold Spring Harbor Laboratory, RIKEN BioResource Center for providing the Arabidopsis mutants and cDNAs; and Professor Nathan Nelson (Tel Aviv University), Dr Mieko Higuchi (RIKEN), Dr Kumiko Kondo (RIKEN) and Dr Fumiyoshi Myouga (RIKEN) for their help in this study. This work was supported in part by Grants-in-Aid for Scientific Research on Innovative Areas (No. 25119714 to T.M., No. 24248014 to N.Y. and No. 22119002 to J.F.M.), Grants-in-Aid for Scientific Research (C) (No. 26460067), the Smoking Research Foundation, the Uehara Memorial Foundation and the Takada Science Foundation to T.M., Grants-in-Aid for Scientific Research (C) (No. 24570063) to T.K., Grants-in-Aid for Scientific Research (B) (No. 21370057) to H.O. and Grants-in-Aid for Scientific Research (A) (No. 25253008), the Salt Science Foundation (No. 1139) and the Japan Science and Technology Agency for Japan-Israel Scientific Research cooperation to Y.M. Publisher Copyright: {\textcopyright} 2015 Macmillan Publishers Limited. All rights reserved.",
year = "2015",
month = jan,
day = "5",
doi = "10.1038/ncomms6928",
language = "English",
volume = "6",
journal = "Nature Communications",
issn = "2041-1723",
publisher = "Nature Publishing Group",
}