The pyruvate dehydrogenase complex from the parasitic nematode Ascaris suum: Novel subunit composition and domain structure of the dihydrolipoyl transacetylase component

Komuniecki, Richard; Rhee, Robert Y.; Bhat, D G; Duran, Emilio; Sidawy, Emil; Song, Hebok

doi:10.1016/0003-9861(92)90552-8

Cited by 13 publications

(10 citation statements)

References 34 publications

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“…E1-depleted PDC and E1 were prepared as described previously (10) with the following modification: dissociation was performed in 50 mM MOPS (pH 7.4), 2 M NaCl, 1 mM MgCl 2 , 0.1 mM EDTA, 3 mM dithiothreitol, and 0.8 mg ml Ϫ1 Pluronic ® F68 (BASF Corp.). After incubation at room temperature for 90 min, the sample was applied to a Sephacryl S-400 column (2.6 ϫ 90 cm) equilibrated with the same buffer.…”

Section: Sequential Dissociation and Resolution Of A Suum Pdc-a Suummentioning

confidence: 99%

“…The procedure was performed as described by the manufacturer. Affinity purified antisera against p45, E1␣, and E1␤ were prepared as described previously (10,25,26). E2 antiserum was affinity-purified in a manner previously described (25,27).…”

Section: Sequential Dissociation and Resolution Of A Suum Pdc-a Suummentioning

confidence: 99%

“…E2 preferentially binds pyruvate dehydrogenase (E1) and exhibits transacetylase activity, whereas E3BP contains a high-affinity binding site for E3 (16). In contrast, incubation of the ascarid complex under similar conditions results in the acetylation of only E2 and no protein corresponding to E3BP has been identified (10). In addition, the PDC from A. suum and other closely related nematodes contains subunits of 43 kDa (p43) and 45 kDa (p45) of unknown function, which do not appear to be present in PDCs from other organisms (17).…”

mentioning

confidence: 98%

“…The subunit composition of the adult ascarid muscle PDC differs significantly from the PDCs isolated from other eukaryotic organisms (7,9,10). In both yeast and mammalian PDCs, incubation of the complex with [2][3][4][5][6][7][8][9][10][11][12][13][14] C]pyruvate in the absence of CoA results in the acetylation of two proteins, dihydrolipoyl transacetylase (E2) and dihydrolipoyl dehydrogenase (E3)-binding protein (BP) (11,12).…”

mentioning

confidence: 99%

“…In both yeast and mammalian PDCs, incubation of the complex with [2][3][4][5][6][7][8][9][10][11][12][13][14] C]pyruvate in the absence of CoA results in the acetylation of two proteins, dihydrolipoyl transacetylase (E2) and dihydrolipoyl dehydrogenase (E3)-binding protein (BP) (11,12). E2 and E3BP are present in a ratio of about 5:1, and both contain similar multidomain structures consisting of an amino-terminal lipoyl domain, a subunit binding domain, and an inner domain (13)(14)(15).…”

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confidence: 99%

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Identification of a Novel Dihydrolipoyl Dehydrogenase-binding Protein in the Pyruvate Dehydrogenase Complex of the Anaerobic Parasitic Nematode, Ascaris suum

Klingbeil

Walker

Arnette

et al. 1996

Journal of Biological Chemistry

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A novel dihydrolipoyl dehydrogenase-binding protein (E3BP) which lacks an amino-terminal lipoyl domain, p45, has been identified in the pyruvate dehydrogenase complex (PDC) of the adult parasitic nematode, Ascaris suum. Sequence at the amino terminus of p45 exhibited significant similarity with internal E3-binding domains of dihydrolipoyl transacetylase (E2) and E3BP. Dissociation and resolution of a pyruvate dehydrogenase-depleted adult A. suum PDC in guanidine hydrochloride resulted in two E3-depleted E2 core preparations which were either enriched or substantially depleted of p45. Following reconstitution, the p45-enriched E2 core exhibited enhanced E3 binding, whereas, the p45-depleted E2 core exhibited dramatically reduced E3 binding. Reconstitution of either the bovine kidney or A. suum PDCs with the A. suum E3 suggested that the ascarid E3 was more sensitive to NADH inhibition when bound to the bovine kidney core. The expression of p45 was developmentally regulated and p45 was most abundant in anaerobic muscle. In contrast, E3s isolated from anaerobic muscle or aerobic second-stage larvae were identical. These results suggest that during the transition to anaerobic metabolism, E3 remains unchanged, but it appears that a novel E3BP, p45, is expressed which may help to maintain the activity of the PDC in the face of the elevated intramitochondrial NADH/NAD ؉ ratios associated with anaerobiosis.The pyruvate dehydrogenase complex (PDC) 1 plays a key role in the unique mitochondrial metabolism of the parasitic nematode, Ascaris suum (1, 2). During larval development, A. suum exhibits a marked aerobic-anaerobic transition in energy metabolism. Early larval stages are aerobic, and the PDC functions to supply acetyl-CoA for tricarboxylic acid cycle oxidation (3). In contrast, energy metabolism in adult ascarid muscle is anaerobic. Adult muscle mitochondria lack both a functional tricarboxylic acid cycle and cytochrome oxidase activity and use unsaturated organic acids, such as fumarate and 2-methyl branched-chain enoyl-CoAs, instead of oxygen, as terminal electron acceptors (4 -6). The PDC is overexpressed in adult muscle and is designed to function under the elevated NADH/ NAD ϩ and acyl-CoA/CoA ratios present in the microaerobic environment of the host gut (7,8).The subunit composition of the adult ascarid muscle PDC differs significantly from the PDCs isolated from other eukaryotic organisms (7, 9, 10). In both yeast and mammalian PDCs, incubation of the complex with [2-14 C]pyruvate in the absence of CoA results in the acetylation of two proteins, dihydrolipoyl transacetylase (E2) and dihydrolipoyl dehydrogenase (E3)-binding protein (BP) (11, 12). E2 and E3BP are present in a ratio of about 5:1, and both contain similar multidomain structures consisting of an amino-terminal lipoyl domain, a subunit binding domain, and an inner domain (13-15). E2 preferentially binds pyruvate dehydrogenase (E1) and exhibits transacetylase activity, whereas E3BP contains a high-affinity binding site for E3 (16). In contrast, ...

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Section: Sequential Dissociation and Resolution Of A Suum Pdc-a Suummentioning

confidence: 99%

Section: Sequential Dissociation and Resolution Of A Suum Pdc-a Suummentioning

confidence: 99%

mentioning

confidence: 98%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Identification of a Novel Dihydrolipoyl Dehydrogenase-binding Protein in the Pyruvate Dehydrogenase Complex of the Anaerobic Parasitic Nematode, Ascaris suum

Klingbeil

Walker

Arnette

et al. 1996

Journal of Biological Chemistry

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Regulation of the pyruvate dehydrogenase complex during the aerobic/anaerobic transition in the development of the parasitic nematode, Ascaris suum

Komuniecki

Klingbeil

Arnette

et al. 1996

Alpha-Keto Acid Dehydrogenase Complexes

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A novel metabolic network leads to enhanced citrate biogenesis in Pseudomonas fluorescens exposed to aluminum toxicity

Mailloux

Lemire²,

Kalyuzhnyi³

et al. 2008

Extremophiles

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Aluminum (Al), an environmental toxin, is known to have a negative impact on various biological systems. However, some microbes have devised intricate mechanisms to combat the toxic influence of this trivalent metal. In this study, Pseudomonas fluorescens grown in malate invoked a unique metabolic shift to promote the synthesis of citrate, a metabolite involved in the sequestration of Al. Electrophoretic and spectrophotometric assays revealed several malate-metabolizing enzymes including malate dehydrogenase (MDH) and malic enzyme (ME) displayed increases in activity and expression in the Al-treated cells. Whereas pyruvate dehydrogenase (PDH) also showed increased activity and expression in the Al-stressed cultures, phosphoenolpyruvate carboxykinase (PEPCK) displayed a marked diminution in the Al-treated cells. The upregulation of citrate synthase (CS) coupled with the diminished activities of aconitase (ACN) and NAD-isocitrate dehydrogenase (NAD-ICDH) appeared to be instrumental in the accumulation of citrate. HPLC experiments revealed high levels of citrate in the Al-stressed cultures. Thus, an Al-enriched environment provoked a metabolic shift in P. fluorescens dedicated to the conversion of malate to citrate.

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The pyruvate dehydrogenase complex from the parasitic nematode Ascaris suum: Novel subunit composition and domain structure of the dihydrolipoyl transacetylase component

Cited by 13 publications

References 34 publications

Identification of a Novel Dihydrolipoyl Dehydrogenase-binding Protein in the Pyruvate Dehydrogenase Complex of the Anaerobic Parasitic Nematode, Ascaris suum

Identification of a Novel Dihydrolipoyl Dehydrogenase-binding Protein in the Pyruvate Dehydrogenase Complex of the Anaerobic Parasitic Nematode, Ascaris suum

Regulation of the pyruvate dehydrogenase complex during the aerobic/anaerobic transition in the development of the parasitic nematode, Ascaris suum

A novel metabolic network leads to enhanced citrate biogenesis in Pseudomonas fluorescens exposed to aluminum toxicity

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