Molecular identification of three Arabidopsis thaliana mitochondrial dicarboxylate carrier isoforms: organ distribution, bacterial expression, reconstitution into liposomes and functional characterization

Abstract

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.

Coexpression-Based Clustering of Arabidopsis Root Genes Predicts Functional Modules in Early Phosphate Deficiency Signaling

“…Three genes, OXOPHYTODIENOATE RE-DUCTASE1 (OPR1), BON ASSOCIATION PROTEIN1 (BAP1), and the lysophosphatidic acid acyltransferase At4g24160, are related to lipid binding, metabolism, or homeostasis. The strongest expression after 1 h was observed for WRKY18 and WRKY40, which have partially redundant roles (Xu et al, 2006), and for PBP1, CALMODULIN LIKE39 (CML39), the transferase AT2g41640, and the dicarboxylate carrier DIC2, which could be involved in the transport of Pi across the inner mitochondrial membrane (Table II; Palmieri et al, 2008).…”

Molecular Identification and Functional Characterization of Arabidopsis thaliana Mitochondrial and Chloroplastic NAD+ Carrier Proteins

“…In recent years several of these transporters have been cloned and investigated at the molecular and biochemical level (22,(31)(32)(33)(34). These studies revealed that some members of the MCF in plants can be present in the plastid membranes (35)(36)(37).…”

Understanding metabolite transport and metabolism in C4 plants through RNA-seq

“…Its high expression is accompanied by the expression of a dicarboxylate carrier, DIC (Table 1) [5 ,8]. Among the mitochondrial carriers that accept malate or OAA, DIC is unique as it catalyzes net carbon import as malate/phosphate or malate/sulfate exchange [41]. In case of phosphate exchange, the electrical field is capable of driving the exchange as malate is negatively charged twice and phosphate is negatively charged three times.…”

“…If instead the C 4 acid is imported into the bundle sheath mitochondria as aspartate, the import protein remains unknown as the DICs of Arabidopsis do not accept amino acids [41].…”

“…The NAD-ME species G. gynandra highly expresses a mitochondria localized AspAT [5 ,13]. It is unclear which transport protein catalyzes the exchange of aspartate and OAA across the mitochondrial envelope ( Figure 1h); the DIC does not transport amino acids [41], and for DTC the transport of amino acids was not tested [47].…”