Anaerobic growth of Escherichia coli on D-tartrate depends on the fumarate carrier DcuB and fumarase, rather than the L-tartrate carrier TtdT and L-tartrate dehydratase.
Escherichia coli is able to grow under anaerobic conditions on D: -tartrate when glycerol is supplied as an electron donor (D-tartrate fermentation). D-Tartrate was converted to succinate. Growth was lost in strains deficient for DcuB, the fumarate/succinate antiporter of fumarate respiration. The L-tartrate/succinate antiporter TtdT of L-tartrate fermentation, or the C4-dicarboxylate carriers DcuA and DcuC, were not able to support D-tartrate transport and fermentation. Deletion of fumB demonstrated, that fumarase B is required for growth on D-tartrate. The mutant lost most (about 79%) of D-tartrate dehydratase activity. L-Tartrate dehydratase (TtdAB), and fumarase A or C, showed no or only a small contribution to D-tartrate dehydratase activity. Therefore D-tartrate is metabolised by a sequence of reactions analogous to that from L-tartrate fermentation, including dehydration to oxaloacetate, which is then converted to malate, fumarate and succinate. The stereoisomer specific carrier TtdT and dehydratase TtdAB of L-tartrate fermentation are substituted by enzymes from general anaerobic fumarate metabolism, the antiporter DcuB and fumarase B, which have a broader substrate specificity. No D-tartrate specific carriers and enzymes are involved in the pathway.
Kim
Ok Bin
OB
Institut für Mikrobiologie und Weinforschung, Universität Mainz, Becherweg 15, 55099 Mainz, Germany.
Lux
Sebastian
S
Unden
Gottfried
G
D000693:Anaerobiosis; D029382:Dicarboxylic Acid Transporters / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D005285:Fermentation; D005649:Fumarate Hydratase / Q000378:metabolism*; D006836:Hydro-Lyases / Q000378:metabolism*; D013237:Stereoisomerism; D013386:Succinates / Q000737:chemistry / Q000378:metabolism; D013644:Tartrates / Q000737:chemistry / Q000378:metabolism*
D029382:Dicarboxylic Acid Transporters; D029968:Escherichia coli Proteins; D013386:Succinates; D013644:Tartrates; C086256:dcuB protein, E coli; D006836:Hydro-Lyases; D005649:Fumarate Hydratase; C083087:L(+)-tartrate dehydratase; C029768:tartaric acid