title: The L-tartrate/succinate antiporter TtdT (YgjE) of L-tartrate fermentation in Escherichia coli.
abstract: Escherichia coli ferments L-tartrate under anaerobic conditions in the presence of an additional electron donor to succinate. The carrier for L-tartrate uptake and succinate export and its relation to the general C(4)-dicarboxylate carriers DcuA, DcuB, and DcuC were studied. The secondary carrier TtdT, encoded by the ttdT (previously called ygjE) gene, is required for the uptake of L-tartrate. The ttdT gene is located downstream of the ttdA and ttdB genes, encoding the L-tartrate dehydratase TtdAB. Analysis of mRNA by reverse transcription-PCR showed that ttdA, ttdB, and ttdT are cotranscribed. Deletion of ttdT abolished growth by L-tartrate and degradation of L-tartrate completely. Bacteria containing TtdT catalyze L-tartrate or succinate uptake and specific heterologous L-tartrate/succinate antiporting. D-Tartrate is not a substrate for TtdT. TtdT operates preferentially in the direction of tartrate uptake and succinate excretion. The Dcu carriers do not support anaerobic growth on L-tartrate or L-tartrate transport. TtdT is related in sequence and function to CitT, which catalyzes heterologous citrate/succinate antiporting in citrate fermentation.
authors.affiliation: Institut für Mikrobiologie und Weinforschung, Johannes Gutenberg-Universität Mainz, Becherweg 15, 55099 Mainz, Germany.
authors.forename: Ok Bin
authors.initials: OB
authors.lastname: Kim
authors.forename: Gottfried
authors.initials: G
authors.lastname: Unden
mesh_terms: D001426:Bacterial Proteins / Q000502:physiology*; D001692:Biological Transport; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D005285:Fermentation; D009876:Operon; D019802:Succinic Acid / Q000378:metabolism*; D013644:Tartrates / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D013644:Tartrates; D019802:Succinic Acid; C029768:tartaric acid