Pyruvate oxidase contributes to the aerobic growth efficiency of Escherichia coli

Abdelhamid, Ahmed; Attwood, Margaret; Guest, John R.

doi:10.1099/00221287-147-6-1483

Cited by 149 publications

(92 citation statements)

References 39 publications

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“…In contrast, cells that constitutively express POXB exhibit increased AMP-ACS activity. Although the mechanisms by which POXB exerts its influence remains unknown, these observations suggest that AMP-ACS may be primarily responsible for activation of the acetate produced by POXB (2).…”

Section: Other Regulatory Factorsmentioning

confidence: 97%

“…When overexpressed or expressed constitutively, POXB can substitute for the PDHC, albeit less efficiently. Thus, it has been proposed that POXB contributes substantially to aerobic growth efficiency (2). How does POXB perform this function?…”

Section: Excretion Pathwaysmentioning

confidence: 99%

“…After prolonged incubation (in the absence of acetate), mutants that lack the PDHC form microcolonies, whose development depends on a functioning POXB (79). The simplest model has POXB and AMP-ACS forming a pyruvate-to-acetyl-CoA bypass of PDHC (2) (Fig. 3 and 5), a model easily tested by the construction of mutants that lack both the PDHC and AMP-ACS.…”

Section: Excretion Pathwaysmentioning

confidence: 99%

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The Acetate Switch

Wolfe

2005

Microbiol Mol Biol Rev

1,068

1,274

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To succeed, many cells must alternate between life-styles that permit rapid growth in the presence of abundant nutrients and ones that enhance survival in the absence of those nutrients. One such change in life-style, the “acetate switch,” occurs as cells deplete their environment of acetate-producing carbon sources and begin to rely on their ability to scavenge for acetate. This review explains why, when, and how cells excrete or dissimilate acetate. The central components of the “switch” (phosphotransacetylase [PTA], acetate kinase [ACK], and AMP-forming acetyl coenzyme A synthetase [AMP-ACS]) and the behavior of cells that lack these components are introduced. Acetyl phosphate (acetyl∼P), the high-energy intermediate of acetate dissimilation, is discussed, and conditions that influence its intracellular concentration are described. Evidence is provided that acetyl∼P influences cellular processes from organelle biogenesis to cell cycle regulation and from biofilm development to pathogenesis. The merits of each mechanism proposed to explain the interaction of acetyl∼P with two-component signal transduction pathways are addressed. A short list of enzymes that generate acetyl∼P by PTA-ACKA-independent mechanisms is introduced and discussed briefly. Attention is then directed to the mechanisms used by cells to “flip the switch,” the induction and activation of the acetate-scavenging AMP-ACS. First, evidence is presented that nucleoid proteins orchestrate a progression of distinct nucleoprotein complexes to ensure proper transcription of its gene. Next, the way in which cells regulate AMP-ACS activity through reversible acetylation is described. Finally, the “acetate switch” as it exists in selected eubacteria, archaea, and eukaryotes, including humans, is described

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Section: Other Regulatory Factorsmentioning

confidence: 97%

Section: Excretion Pathwaysmentioning

confidence: 99%

Section: Excretion Pathwaysmentioning

confidence: 99%

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The Acetate Switch

Wolfe

2005

Microbiol Mol Biol Rev

1,068

1,274

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“…Accordingly, the authors speculated that the enzyme might be responsible for oxidative pyruvate decarboxylation during the transition between the exponential aerobic growth phase and the stationary growth phase when cultures become anaerobic. Further studies with poxB inactivation mutants and with poxBoverexpressing strains of E. coli indicated that PQO activity contributes to the aerobic growth efficiency and that a high PQO activity, together with acetyl-coenzyme A (CoA) synthetase, can compensate for the pyruvate dehydrogenase complex function (1,25).Very recently, we showed for the first time the presence of PQO activity in a prokaryotic organism apart from E. coli and described the isolation, purification, and biochemical analysis of the PQO enzyme from Corynebacterium glutamicum (59). This bacterium is an aerobic, "high-GC gram-positive" organism that grows on a variety of sugars and organic acids and is widely used in the industrial production of amino acids, particularly L-glutamate and L-lysine (35).…”

mentioning

confidence: 99%

Pyruvate:Quinone Oxidoreductase in Corynebacterium glutamicum : Molecular Analysis of the pqo Gene, Significance of the Enzyme, and Phylogenetic Aspects

et al. 2006

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Corynebacterium glutamicum recently has been shown to possess pyruvate:quinone oxidoreductase (PQO), catalyzing the oxidative decarboxylation of pyruvate to acetate and CO 2 with a quinone as the electron acceptor. Here, we analyze the expression of the C. glutamicum pqo gene, investigate the relevance of the PQO enzyme for growth and amino acid production, and perform phylogenetic studies. Expression analyses revealed that transcription of pqo is initiated 45 bp upstream of the translational start site and that it is organized in an operon together with genes encoding a putative metal-activated pyridoxal enzyme and a putative activator protein. Inactivation of the chromosomal pqo gene led to the absence of PQO activity; however, growth and amino acid production were not affected under either condition tested. Introduction of plasmid-bound pqo into a pyruvate dehydrogenase complex-negative C. glutamicum strain partially relieved the growth phenotype of this mutant, indicating that high PQO activity can compensate for the function of the pyruvate dehydrogenase complex. To investigate the distribution of PQO enzymes in prokaryotes and to clarify the relationship between PQO, pyruvate oxidase (POX), and acetohydroxy acid synthase enzymes, we compiled and analyzed the phylogeny of respective proteins deposited in public databases. The analyses revealed a wide distribution of PQOs among prokaryotes, corroborated the hypothesis of a common ancestry of the three enzymes, and led us to propose that the POX enzymes of Lactobacillales were derived from a PQO.Pyruvate:quinone oxidoreductase (PQO) (EC 1.2.2.2) catalyzes the oxidative decarboxylation of pyruvate to acetate and CO 2 with a quinone as the physiological electron acceptor. The Escherichia coli PQO enzyme, also designated pyruvate oxidase (POX), is a nonessential, peripheral membrane protein consisting of four identical subunits, each containing tightly bound flavin adenine dinucleotide (FAD) and loosely bound thiamine pyrophosphate (TPP) and Mg 2ϩ (4,22,37,38,75). This enzyme has been shown to be strongly activated by low concentrations of phospholipids and detergents (5,8,15,16,28), and the activation has been shown to be accompanied by conformational changes and alteration of various properties of the enzyme (11,12,74). Aside from extensive biochemical characterization of the E. coli PQO, the respective gene ( poxB) and its expression have been studied in detail (7, 9, 25). Expression of the poxB gene was dependent on sigma factor RpoS and thus induced in the stationary growth phase (7). Accordingly, the authors speculated that the enzyme might be responsible for oxidative pyruvate decarboxylation during the transition between the exponential aerobic growth phase and the stationary growth phase when cultures become anaerobic. Further studies with poxB inactivation mutants and with poxBoverexpressing strains of E. coli indicated that PQO activity contributes to the aerobic growth efficiency and that a high PQO activity, together with acetyl-coenzyme A (CoA) syn...

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“…Pyruvate oxidase delivers the electrons resulting from the oxidation of pyruvate directly to the respiratory chain and has been shown to contribute to the aerobic growth efficiency of E. coli (33). Despite its role in aerobic metabolism, we found that a pyruvate oxidase-deficient strain grew and fermented glucose in a wild-type manner (data not shown).…”

Section: Kinetics Of Glucose Fermentation In Wild-type Mg1655 and A Pmentioning

confidence: 78%

Metabolic Analysis of Wild-type Escherichia coli and a Pyruvate Dehydrogenase Complex (PDHC)-deficient Derivative Reveals the Role of PDHC in the Fermentative Metabolism of Glucose

Murarka

Clomburg

Moran

et al. 2010

Journal of Biological Chemistry

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Pyruvate is located at a metabolic junction of assimilatory and dissimilatory pathways and represents a switch point between respiratory and fermentative metabolism. In Escherichia coli, the pyruvate dehydrogenase complex (PDHC) and pyruvate formate-lyase are considered the primary routes of pyruvate conversion to acetyl-CoA for aerobic respiration and anaerobic fermentation, respectively. During glucose fermentation, the in vivo activity of PDHC has been reported as either very low or undetectable, and the role of this enzyme remains unknown. In this study, a comprehensive characterization of wild-type E. coli MG1655 and a PDHC-deficient derivative (Pdh) led to the identification of the role of PDHC in the anaerobic fermentation of glucose. The metabolism of these strains was investigated by using a mixture of 13 C-labeled and -unlabeled glucose followed by the analysis of the labeling pattern in protein-bound amino acids via two-dimensional 13 C, 1 H NMR spectroscopy. Metabolite balancing, biosynthetic 13 C labeling of proteinogenic amino acids, and isotopomer balancing all indicated a large increase in the flux of the oxidative branch of the pentose phosphate pathway (ox-PPP) in response to the PDHC deficiency. Because both ox-PPP and PDHC generate CO 2 and the calculated CO 2 evolution rate was significantly reduced in Pdh, it was hypothesized that the role of PDHC is to provide CO 2 for cell growth. The similarly negative impact of either PDHC or ox-PPP deficiencies, and an even more pronounced impairment of cell growth in a strain lacking both ox-PPP and PDHC, provided further support for this hypothesis. The three strains exhibited similar phenotypes in the presence of an external source of CO 2 , thus confirming the role of PDHC. Activation of formate hydrogen-lyase (which converts formate to CO 2 and H 2 ) rendered the PDHC deficiency silent, but its negative impact reappeared in a strain lacking both PDHC and formate hydrogen-lyase. A stoichiometric analysis of CO 2 generation via PDHC and ox-PPP revealed that the PDHC route is more carbon-and energy-efficient, in agreement with its beneficial role in cell growth.The fermentative metabolism of glucose has been extensively studied in many organisms, especially in the model bacterium Escherichia coli (1). As shown in Fig. 1, glucose is concomitantly transported and phosphorylated by the phosphoenolpyruvatedependent phosphotransferase system (2, 3). The resulting glucose 6-phosphate is processed via the Embden-Meyerhof-Parnas (EMP) 2 pathway and the pentose phosphate pathway (PPP) (4) to provide ATP, reducing power and carbon skeletons for biosynthesis. In the absence of external electron acceptors (i.e. under fermentative conditions), E. coli converts most of the glucose to a mixture of organic acids (acetate, formate, lactate, and succinate), ethanol, carbon dioxide, and hydrogen ( Fig. 1) (1). Most of these fermentation products are generated from pyruvate ( Fig. 1).Pyruvate is located at a major metabolic node linking carbohydrate catabolism to energy...

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Pyruvate oxidase contributes to the aerobic growth efficiency of Escherichia coli

Cited by 149 publications

References 39 publications

The Acetate Switch

The Acetate Switch

Pyruvate:Quinone Oxidoreductase in Corynebacterium glutamicum : Molecular Analysis of the pqo Gene, Significance of the Enzyme, and Phylogenetic Aspects

Metabolic Analysis of Wild-type Escherichia coli and a Pyruvate Dehydrogenase Complex (PDHC)-deficient Derivative Reveals the Role of PDHC in the Fermentative Metabolism of Glucose

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