Journal Article

Identifying and Characterizing Plastidic 2-Oxoglutarate/Malate and Dicarboxylate Transporters in <i>Arabidopsis thaliana</i>

Mitsutaka Taniguchi, Yojiro Taniguchi, Michio Kawasaki, Satomi Takeda, Tomohiko Kato, Shusei Sato, Satoshi Tabata, Hiroshi Miyake and Tatsuo Sugiyama

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 43, issue 7, pages 706-717
Published in print July 2002 | ISSN: 0032-0781
Published online July 2002 | e-ISSN: 1471-9053 | DOI:
Identifying and Characterizing Plastidic 2-Oxoglutarate/Malate and Dicarboxylate Transporters in Arabidopsis thaliana

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  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry


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We characterized three Arabidopsis genes, AtpOMT1, AtpDCT1 and AtpDCT2, localized on chromosome 5 and homologous to spinach chloroplastic 2-oxoglutarate/malate transporter (OMT) gene. The yeast-expressed recombinant AtpOMT1 protein transported malate and 2-oxoglutarate but not glutamate. By contrast, the recombinant AtpDCT1 protein transported 2-oxoglutarate and glutamate at similar affinities in exchange for malate. These findings suggested that AtpOMT1 is OMT and AtpDCT1 is a general dicarboxylate transporter (DCT). The recombinant proteins could also transport oxaloacetate at the same binding sites for dicarboxylates. In particular, the AtpOMT1 had a Km value for oxaloacetate one order of magnitude lower than those for malate and 2-oxoglutarate. Although the transcripts for the three genes were accumulated in all tissues examined, the expression of the genes in leaf tissues was light inducible. The expression of the three genes was also induced by nitrate supplement but the induction was most prominent and transient in AtpOMT1 similar to nitrate reductase gene. These findings lead to a proposition that AtpOMT1 functions as an oxaloacetate transporter in the malate–oxaloacetate shuttle across chloroplast membranes. We identified T-DNA insertional mutants of AtpOMT1 and AtpDCT1. Although the AtpOMT1 mutants could grow normally in normal air, the AtpDCT1 mutants were non-viable under the same conditions. The AtpDCT1 mutants were able to grow under the high CO2 condition to suppress photorespiration. These findings suggested that at least AtpDCT1 is a necessary component for photorespiratory nitrogen recycling.

Keywords: Keywords: Arabidopsis thaliana –– Dicarboxylate transporter –– Oxaloacetate transporter –– 2-Oxoglutarate/malate transporter –– Plastid.; Abbreviations: chlMDH, chloroplastic malate dehydrogenase; cytMDH, cytosolic malate dehydrogenase; DCT, dicarboxylate transporter; EST, expression sequence tag; GS, glutamine synthetase; GOGAT, glutamate synthase; MDH, malate dehydrogenase; NR, nitrate reductase; OAT, oxaloacetate transporter; OMT, 2-oxoglutarate/malate transporter; RT-PCR, reverse transcription-polymerase chain reaction.

Journal Article.  7627 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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