Characterization of the dicarboxylate transporter DctA in Corynebacterium glutamicum.

Transporters of the dicarboxylate amino acid-cation symporter family often mediate uptake of C(4)-dicarboxylates, such as succinate or l-malate, in bacteria. A member of this family, dicarboxylate transporter A (DctA) from Corynebacterium glutamicum, was characterized to catalyze uptake of the C(4)-dicarboxylates succinate, fumarate, and l-malate, which was inhibited by oxaloacetate, 2-oxoglutarate, and glyoxylate. DctA activity was not affected by sodium availability but was dependent on the electrochemical proton potential. Efficient growth of C. glutamicum in minimal medium with succinate, fumarate, or l-malate as the sole carbon source required high dctA expression levels due either to a promoter-up mutation identified in a spontaneous mutant or to ectopic overexpression. Mutant analysis indicated that DctA and DccT, a C(4)-dicarboxylate divalent anion/sodium symporter-type transporter, are the only transporters for succinate, fumarate, and l-malate in C. glutamicum.