Molecular identification of three Arabidopsis thaliana mitochondrial dicarboxylate carrier isoforms: organ distribution, bacterial expression, reconstitution into liposomes and functional characterization.
Screening of the Arabidopsis thaliana genome revealed three potential homologues of mammalian and yeast mitochondrial DICs (dicarboxylate carriers) designated as DIC1, DIC2 and DIC3, each belonging to the mitochondrial carrier protein family. DIC1 and DIC2 are broadly expressed at comparable levels in all the tissues investigated. DIC1-DIC3 have been reported previously as uncoupling proteins, but direct transport assays with recombinant and reconstituted DIC proteins clearly demonstrate that their substrate specificity is unique to plants, showing the combined characteristics of the DIC and oxaloacetate carrier in yeast. Indeed, the Arabidopsis DICs transported a wide range of dicarboxylic acids including malate, oxaloacetate and succinate as well as phosphate, sulfate and thiosulfate at high rates, whereas 2-oxoglutarate was revealed to be a very poor substrate. The role of these plant mitochondrial DICs is discussed with respect to other known mitochondrial carrier family members including uncoupling proteins. It is proposed that plant DICs constitute the membrane component of several metabolic processes including the malate-oxaloacetate shuttle, the most important redox connection between the mitochondria and the cytosol.
Department of Pharmaco-Biology, Laboratory of Biochemistry and Molecular Biology, University of Bari, Via Orabona 4, 70125 Bari, Italy.
Luigi
L
Palmieri
Nathalie
N
Picault
Roberto
R
Arrigoni
Evelyne
E
Besin
Ferdinando
F
Palmieri
Michael
M
Hodges
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000378:metabolism*; D001483:Base Sequence; D017931:DNA Primers; D018076:DNA, Complementary; D029382:Dicarboxylic Acid Transporters / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D007700:Kinetics; D008081:Liposomes; D008928:Mitochondria / Q000378:metabolism*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D020033:Protein Isoforms / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D018076:DNA, Complementary; D029382:Dicarboxylic Acid Transporters; D008081:Liposomes; D020033:Protein Isoforms; D011994:Recombinant Proteins