US EPA

2987872 

Journal Article 

Oxaloacetate transport into plant mitochondria 

Hanning, I; Baumgarten, I; Schott, I; Heldt, I 

1999 

1 

Plant Physiology
ISSN: 0032-0889
EISSN: 1532-2548 

119 

3 

1025-1032 

English 

10069840 

10.1104/pp.119.3.1025 

WOS:000079102000021 

https://academic.oup.com/plphys/article/119/3/1025/6087501
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The properties of oxaloacetate (OA) transport into mitochondria from potato (Solanum tuberosum) tuber and pea (Pisum sativum) leaves were studied by measuring the uptake of 14C-labeled OA into liposomes with incorporated mitochondrial membrane proteins preloaded with various dicarboxylates or citrate. OA was found to be transported in an obligatory counterexchange with malate, 2-oxoglutarate, succinate, citrate, or aspartate. Phtalonate inhibited all of these countertransports. OA-malate countertransport was inhibited by 4, 4'-dithiocyanostilbene-2,2'-disulfonate and pyridoxal phosphate, and also by p-chloromercuribenzene sulfonate and mersalyl, indicating that a lysine and a cysteine residue of the translocator protein are involved in the transport. From these and other inhibition studies, we concluded that plant mitochondria contain an OA translocator that differs from all other known mitochondrial translocators. Major functions of this translocator are the export of reducing equivalents from the mitochondria via the malate-OA shuttle and the export of citrate via the citrate-OA shuttle. In the cytosol, citrate can then be converted either into 2-oxoglutarate for use as a carbon skeleton for nitrate assimilation or into acetyl-coenzyme A for use as a precursor for fatty acid elongation or isoprenoid biosynthesis.