An unusual type of regulation of malate oxidase synthesis in Escherichiacoli

Goldie, A H; Narindrasorasak, Suree; Sanwal, B. D.

doi:10.1016/0006-291x(78)91007-0

Cited by 11 publications

(7 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…2 indicate that the MQO activity, in contrast to the MDH activity, is highly dependent on the growth phase and that the activity decreases rapidly when the cells reach the stationary phase. The same observation was made for another strain (K-12 strain DSM 5698) and was also described earlier (12). Properties of mdh and mqo deletion strains.…”

Section: Hydrolysis Of Ortho-nitrophenyl-␤-d-galactopyranoside (Onpg)supporting

confidence: 66%

“…Earlier reports suggested that the level of MQO activity was down-regulated to very low levels by the presence of active MDH (12,25). The increase in MQO activity in mutants lacking MDH activity could amount to a factor of 200 to 300 over the MQO activity found in the wild type.…”

Section: Discussionmentioning

confidence: 95%

“…Earlier investigations suggested that MQO in E. coli was present in only (some) mutants lacking the cytoplasmic malate dehydrogenase (12,25). These authors interpreted the results as indicating that there existed a repressing effect of MDH on MQO expression, which was dependent on the presence of active MDH.…”

Section: Hydrolysis Of Ortho-nitrophenyl-␤-d-galactopyranoside (Onpg)mentioning

confidence: 99%

“…This activity was thought to be induced to significant levels only in certain mutants lacking MDH activity (12). Because an MDHnegative mutant which still contained inactive MDH protein exhibited very high MQO activity, it was surmised that the expression of the gene encoding MQO was regulated by substrates or products of the MDH reaction (25).…”

mentioning

confidence: 99%

See 3 more Smart Citations

Functions of the Membrane-Associated and Cytoplasmic Malate Dehydrogenases in the Citric Acid Cycle of Escherichia coli

2000

View full text Add to dashboard Cite

Oxidation of malate to oxaloacetate in Escherichia coli can be catalyzed by two enzymes: the well-known NAD-dependent malate dehydrogenase (MDH; EC 1.1.1.37) and the membrane-associated malate:quinoneoxidoreductase (MQO; EC 1.1.99.16), encoded by the gene mqo (previously called yojH). Expression of the mqo gene and, consequently, MQO activity are regulated by carbon and energy source for growth. In batch cultures, MQO activity was highest during exponential growth and decreased sharply after onset of the stationary phase. Experiments with the ␤-galactosidase reporter fused to the promoter of the mqo gene indicate that its transcription is regulated by the ArcA-ArcB two-component system. In contrast to earlier reports, MDH did not repress mqo expression. On the contrary, MQO and MDH are active at the same time in E. coli. For Corynebacterium glutamicum, it was found that MQO is the principal enzyme catalyzing the oxidation of malate to oxaloacetate. These observations justified a reinvestigation of the roles of MDH and MQO in the citric acid cycle of E. coli. In this organism, a defined deletion of the mdh gene led to severely decreased rates of growth on several substrates. Deletion of the mqo gene did not produce a distinguishable effect on the growth rate, nor did it affect the fitness of the organism in competition with the wild type. To investigate whether in an mqo mutant the conversion of malate to oxaloacetate could have been taken over by a bypass route via malic enzyme, phosphoenolpyruvate synthase, and phosphenolpyruvate carboxylase, deletion mutants of the malic enzyme genes sfcA and b2463 (coding for EC 1.1.1.38 and EC 1.1.1.40, respectively) and of the phosphoenolpyruvate synthase (EC 2.7.9.2) gene pps were created. They were introduced separately or together with the deletion of mqo. These studies did not reveal a significant role for MQO in malate oxidation in wild-type E. coli. However, comparing growth of the mdh single mutant to that of the double mutant containing mdh and mqo deletions did indicate that MQO partly takes over the function of MDH in an mdh mutant.In Escherichia coli, several enzymes or pathways are able to convert malate to oxaloacetate. The NAD-dependent (cytoplasmic) malate dehydrogenase (MDH; EC 1.1.1.37) has always been considered to be the principal malate-oxidizing enzyme in the citric acid cycle (tricarboxylic acid [TCA] cycle) of this organism (9). Recently, a malate:quinone-oxidoreductase (MQO; EC 1.1.99.16) which is an essential enzyme in the TCA cycle of Corynebacterium glutamicum (reference 23 and accompanying paper) was described. MQO is a flavin adenine dinucleotide (FAD)-and lipid-dependent peripheral membrane protein catalyzing the oxidation of L-malate to oxaloacetate. The electrons are donated to the electron transfer chain at the level of quinones. This reaction is essentially irreversible (17). In C. glutamicum, MQO and the cytoplasmic NAD-dependent malate dehydrogenase, which is capable of reversible oxidation of malate to oxaloacetate, are active at the sam...

show abstract

Section: Hydrolysis Of Ortho-nitrophenyl-␤-d-galactopyranoside (Onpg)supporting

confidence: 66%

Section: Discussionmentioning

confidence: 95%

Section: Hydrolysis Of Ortho-nitrophenyl-␤-d-galactopyranoside (Onpg)mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Functions of the Membrane-Associated and Cytoplasmic Malate Dehydrogenases in the Citric Acid Cycle of Escherichia coli

2000

View full text Add to dashboard Cite

show abstract

“…No genes for SCS, Mdh, or glyoxylate shunt enzymes were identified. Membranebound Mqo, a replacement for Mdh in diverse bacteria (18,36), is present. The enzymes needed to convert acetate to acetyl-CoA, allowing acetate removal by the CAC, are also present: acetyl-CoA synthetase (Acs) or acetate kinase (AckA) and phosphotransacetylase (Pta).…”

Section: Inferred Metabolic Fates Of Acetatementioning

confidence: 99%

A Specialized Citric Acid Cycle Requiring Succinyl-Coenzyme A (CoA):Acetate CoA-Transferase (AarC) Confers Acetic Acid Resistance on the Acidophile Acetobacter aceti

2008

View full text Add to dashboard Cite

Microbes tailor macromolecules and metabolism to overcome specific environmental challenges. Acetic acid bacteria perform the aerobic oxidation of ethanol to acetic acid and are generally resistant to high levels of these two membrane-permeable poisons. The citric acid cycle (CAC) is linked to acetic acid resistance in Acetobacter aceti by several observations, among them the oxidation of acetate to CO 2 by highly resistant acetic acid bacteria and the previously unexplained role of A. aceti citrate synthase (AarA) in acetic acid resistance at a low pH. Here we assign specific biochemical roles to the other components of the A. aceti strain 1023 aarABC region. AarC is succinyl-coenzyme A (CoA):acetate CoA-transferase, which replaces succinyl-CoA synthetase in a variant CAC. This new bypass appears to reduce metabolic demand for free CoA, reliance upon nucleotide pools, and the likely effect of variable cytoplasmic pH upon CAC flux. The putative aarB gene is reassigned to SixA, a known activator of CAC flux. Carbon overflow pathways are triggered in many bacteria during metabolic limitation, which typically leads to the production and diffusive loss of acetate. Since acetate overflow is not feasible for A. aceti, a CO 2 loss strategy that allows acetic acid removal without substrate-level (de)phosphorylation may instead be employed. All three aar genes, therefore, support flux through a complete but unorthodox CAC that is needed to lower cytoplasmic acetate levels.

show abstract

Malate oxidase

Schomburg¹,

Stephan²

1995

Enzyme Handbook 10

View full text Add to dashboard Cite

An unusual type of regulation of malate oxidase synthesis in Escherichiacoli

Cited by 11 publications

References 12 publications

Functions of the Membrane-Associated and Cytoplasmic Malate Dehydrogenases in the Citric Acid Cycle of Escherichia coli

Functions of the Membrane-Associated and Cytoplasmic Malate Dehydrogenases in the Citric Acid Cycle of Escherichia coli

A Specialized Citric Acid Cycle Requiring Succinyl-Coenzyme A (CoA):Acetate CoA-Transferase (AarC) Confers Acetic Acid Resistance on the Acidophile Acetobacter aceti

Malate oxidase

Contact Info

Product

Resources

About