Regulation of aerobic and anaerobic D-malate metabolism of Escherichia coli by the LysR-type regulator DmlR (YeaT).
Escherichia coli K-12 is able to grow under aerobic conditions on D-malate using DctA for D-malate uptake and the D-malate dehydrogenase DmlA (formerly YeaU) for converting D-malate to pyruvate. Induction of dmlA encoding DmlA required an intact dmlR (formerly yeaT) gene, which encodes DmlR, a LysR-type transcriptional regulator. Induction of dmlA by DmlR required the presence of D-malate or L- or meso-tartrate, but only D-malate supported aerobic growth. The regulator of general C(4)-dicarboxylate metabolism (DcuS-DcuR two-component system) had some effect on dmlA expression. The anaerobic L-tartrate regulator TtdR or the oxygen sensors ArcB-ArcA and FNR did not have a major effect on dmlA expression. DmlR has a high level of sequence identity (49%) with TtdR, the L- and meso-tartrate-specific regulator of L-tartrate fermentation in E. coli. dmlA was also expressed at high levels under anaerobic conditions, and the bacteria had D-malate dehydrogenase activity. These bacteria, however, were not able to grow on D-malate since the anaerobic pathway for D-malate degradation has a predicted yield of < or = 0 ATP/mol D-malate. Slow anaerobic growth on D-malate was observed when glycerol was also provided as an electron donor, and D-malate was used in fumarate respiration. The expression of dmlR is subject to negative autoregulation. The network for regulation and coordination of the central and peripheral pathways for C(4)-dicarboxylate metabolism by the regulators DcuS-DcuR, DmlR, and TtdR is discussed.
Lukas
Hanna
H
Institut für Mikrobiologie und Weinforschung, Johannes-Gutenberg-Universität Mainz, Becherweg 15, 55099 Mainz, Germany.
Reimann
Julia
J
Kim
Ok Bin
OB
Grimpo
Jan
J
Unden
Gottfried
G
D000332:Aerobiosis / Q000235:genetics / Q000502:physiology*; D000693:Anaerobiosis / Q000235:genetics / Q000502:physiology*; D002851:Chromatography, High Pressure Liquid; D048168:Escherichia coli K12 / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics / Q000502:physiology*; D008291:Malate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D008293:Malates / Q000378:metabolism*; D009154:Mutation; D013644:Tartrates / Q000378:metabolism; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
D029968:Escherichia coli Proteins; D008293:Malates; D013644:Tartrates; C030298:malic acid; D008291:Malate Dehydrogenase; D001616:beta-Galactosidase