AtPHT4;4 is a chloroplast-localized ascorbate transporter in Arabidopsis

Takaaki Miyaji, Takashi Kuromori, Yu Takeuchi, Naoki Yamaji, Kengo Yokosho, Atsushi Shimazawa, Eriko Sugimoto, Hiroshi Omote, Jian Feng Ma, Kazuo Shinozaki, Yoshinori Moriyama

Research output: Contribution to journalArticle

73 Citations (Scopus)

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.

Original languageEnglish
Article number5928
JournalNature communications
Volume6
DOIs
Publication statusPublished - Jan 5 2015

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

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