Disease relevance of dctA

• Inactivation and regulation of the aerobic C(4)-dicarboxylate transport (dctA) gene of Escherichia coli [1].
• Rhizobium meliloti DctD (C4-dicarboxylate transport protein D) is a transcriptional activator that catalyzes the ATP-dependent isomerization of closed complexes between sigma 54-RNA polymerase holoenzyme and the dctA promoter to open complexes [2].
• Transcriptional regulation and mutational analysis of a dctA gene encoding an organic acid transporter protein from Pseudomonas chlororaphis O6 [3].
• Utilization of orotate as a pyrimidine source by Salmonella typhimurium and Escherichia coli requires the dicarboxylate transport protein encoded by dctA [4].

High impact information on dctA

• CRP interacts with promoter-bound sigma54 RNA polymerase and blocks transcriptional activation of the dctA promoter [5].
• The computer-generated hypotheses for missing reactions were verified experimentally in five cases, leading to the functional assignment of eight ORFs (yjjLMN, yeaTU, dctA, idnT, and putP) with two new enzymatic activities and four transport functions [6].
• In the present communication, we demonstrate, through biochemical analysis of the transport mutants, that the two membrane transport genes, dctA and dctB, are responsible for the two membrane-bound dicarboxylate binding proteins, SBP 2 and SBP 1, respectively [7].
• Expression of the dctA transcript was repressed in early-log cells upon addition of glucose to fumarate, but was detected as the cell culture aged [3].
• The dctA transcript accumulated weakly when cells were grown on malate, but strong expression was observed with benzoate [3].

Chemical compound and disease context of dctA

• The E. coli dctA gene was cloned from a lambda vector and shown to complement C4-dicarboxylate and orotate utilization in FOA-resistant mutants of both E. coli and S. typhimurium [4].
• Two C4-dicarboxylate transport systems in Rhizobium sp. NGR234: rhizobial dicarboxylate transport is essential for nitrogen fixation in tropical legume symbioses [8].

Biological context of dctA

• Expression of the fumarate reductase (frdABCD) operon and the aerobic C4-dicarboxylate transporter (dctA) gene were induced 22- and 4-fold, respectively, by the DcuS-DcuR system in the presence of C4-dicarboxylates [9].
• One locus was chromosomally located, whereas the other was carried on the symbiotic plasmid (pSym) and contained a dctA carrier protein gene, which was analyzed in detail [8].
• A site-directed internal deletion mutant in dctA of NGR234 exhibited a (unique) exclusively symbiotic phenotype that could grow on dicarboxylates ex planta, but could not fix nitrogen in planta [8].
• The nucleotide sequence of the control region of the structural dctA and the regulatory dctBD genes has been determined [10].
• Here we confirm the identity of sigma 54-dependent promoters previously hypothesized for the R. leguminosarum and R. meliloti dctA genes and demonstrate that repeated, partial dyad symmetry elements located about 75 base pairs upstream of each promoter are essential for fully regulated transcription [11].

Associations of dctA with chemical compounds

• The accumulated results demonstrate that the dctA gene product, in addition to transporting C4-dicarboxylates, mediates the transport of orotate, a cyclic monocarboxylate [4].
• Genes of the aerobic C4-dicarboxylate pathway encoding succinate dehydrogenase (sdhCDAB) and the aerobic succinate carrier (dctA) are only marginally or negatively regulated by the DcuSR system [12].
• Expression of the dctA gene was induced in minimal medium by several organic acids and was repressed by glucose [3].
• A dctA-deficient mutant of PcO6, constructed by marker exchange mutagenesis, did not grow on minimal medium containing succinate, benzoate, acetate or fumarate and growth on malate was delayed [3].
• The dctA mutant and wild-type grew equally on citrate, glucose, fructose, sucrose or inositol [3].

Other interactions of dctA

• The expression of dcuB is entirely consistent with a primary role for DcuB in mediating C4-dicarboxylate transport during anaerobic fumarate respiration [13].
• The dcuS mutation affected the expression of other genes with roles in C4-dicarboxylate transport or metabolism [9].

Analytical, diagnostic and therapeutic context of dctA

• In gel retardation assays with target promoters (frdA, dcuB, dctA), phosphoryl DcuR (DcuR-P) formed a high-affinity complex, with an apparent K(D) (app. K(D)) of 0.2-0.3 microM DcuR-P, and a low-affinity (app. K(D) 0.8-2 microM) complex [14].

References