Disorders of pyruvate carboxylase and the pyruvate dehydrogenase complex

1996 ◽  
Vol 19 (4) ◽  
pp. 452-462 ◽  
Author(s):  
B. H. Robinson ◽  
N. MacKay ◽  
K. Chun ◽  
M. Ling
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Pyruvate Carboxylase ◽  
Pyruvate Dehydrogenase Complex ◽  
Dehydrogenase Complex

scholarly journals The impact of CO2/HCO3-availability on anaplerotic flux in PDHC-deficientCorynebacterium glutamicumstrains

2019 ◽  
Author(s):  
Aileen Krüger ◽  
Johanna Wiechert ◽  
Cornelia Gätgens ◽  
Tino Polen ◽  
Regina Mahr ◽  
...  
Keyword(s):  
Corynebacterium Glutamicum ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Carboxylase ◽  
Metabolic Flux ◽  
Pyruvate Dehydrogenase Complex ◽  
Lag Phase ◽  
Metabolic Reaction ◽  
Production Rates ◽  
The Impact ◽  
Dehydrogenase Complex

AbstractThe pyruvate dehydrogenase complex (PDHC) catalyzes the oxidative decarboxylation of pyruvate yielding acetyl-CoA and CO2. The PDHC-deficientCorynebacterium glutamicumstrain ΔaceEis therefore lacking an important decarboxylation step in central metabolism. Additional inactivation ofpyc, encoding pyruvate carboxylase, resulted in a >15 hour lag phase in the presence of glucose, while no growth defect was observed on gluconeogenetic substrates like acetate. Growth was successfully restored by deletion ofptsGencoding the glucose-specific permease of the PTS system, thereby linking the observed phenotype to the increased sensitivity of strain ΔaceEΔpycto glucose catabolism. In the following, strain ΔaceEΔpycwas used to systematically study the impact of perturbations of the intracellular CO2/HCO3-pool on growth and anaplerotic flux. Remarkably, all measures leading to enhanced CO2/HCO3-levels, such as external addition of HCO3-, increasing the pH, or rerouting metabolic flux via pentose phosphate pathway, at least partially eliminated the lag phase of strain ΔaceEΔpycon glucose medium. In accordance, inactivation of the urease enzyme, lowering the intracellular CO2/HCO3-pool, led to an even longer lag phase accompanied with the excretion of L-valine and L-alanine. Transcriptome analysis as well as an adaptive laboratory evolution experiment of strain ΔaceEΔpycrevealed the reduction of glucose uptake as a key adaptive measure to enhance growth on glucose/acetate mixtures. Altogether, our results highlight the significant impact of the intracellular CO2/HCO3-pool on metabolic flux distribution, which becomes especially evident in engineered strains suffering from low endogenous CO2production rates as exemplified by PDHC-deficient strains.ImportanceCO2is a ubiquitous product of cellular metabolism and an essential substrate for carboxylation reactions. The pyruvate dehydrogenase complex (PDHC) catalyzes a central metabolic reaction contributing to the intracellular CO2/HCO3-pool in many organisms. In this study, we used a PDHC-deficient strain ofCorynebacterium glutamicum, which was additionally lacking pyruvate carboxylase (ΔaceEΔpyc). This strain featured a >15 h lag phase during growth on glucose-acetate mixtures. We used this strain to systematically assess the impact of alterations in the intracellular CO2/HCO3-pool on growth on glucose-containing medium. Remarkably, all measures enhancing the CO2/HCO3-levels successfully restored growth emphasizing the strong impact of the intracellular CO2/HCO3-pool on metabolic flux especially in strains suffering from low endogenous CO2production rates.

scholarly journals Impact of CO2/HCO3– Availability on Anaplerotic Flux in Pyruvate Dehydrogenase Complex-Deficient Corynebacterium glutamicum Strains

2019 ◽  
Vol 201 (20) ◽  
Author(s):  
Aileen Krüger ◽  
Johanna Wiechert ◽  
Cornelia Gätgens ◽  
Tino Polen ◽  
Regina Mahr ◽  
...  
Keyword(s):  
Corynebacterium Glutamicum ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Carboxylase ◽  
Metabolic Flux ◽  
Pyruvate Dehydrogenase Complex ◽  
Lag Phase ◽  
Production Rates ◽  
Content Type ◽  
The Impact ◽  
Dehydrogenase Complex

ABSTRACT The pyruvate dehydrogenase complex (PDHC) catalyzes the oxidative decarboxylation of pyruvate, yielding acetyl coenzyme A (acetyl-CoA) and CO2. The PDHC-deficient Corynebacterium glutamicum ΔaceE strain therefore lacks an important decarboxylation step in its central metabolism. Additional inactivation of pyc, encoding pyruvate carboxylase, resulted in a >15-h lag phase in the presence of glucose, while no growth defect was observed on gluconeogenetic substrates, such as acetate. Growth was successfully restored by deletion of ptsG, encoding the glucose-specific permease of the phosphotransferase system (PTS), thereby linking the observed phenotype to the increased sensitivity of the ΔaceE Δpyc strain to glucose catabolism. In this work, the ΔaceE Δpyc strain was used to systematically study the impact of perturbations of the intracellular CO2/HCO3– pool on growth and anaplerotic flux. Remarkably, all measures leading to enhanced CO2/HCO3– levels, such as external addition of HCO3–, increasing the pH, or rerouting metabolic flux via the pentose phosphate pathway, at least partially eliminated the lag phase of the ΔaceE Δpyc strain on glucose medium. In accordance with these results, inactivation of the urease enzyme, lowering the intracellular CO2/HCO3– pool, led to an even longer lag phase, accompanied by the excretion of l-valine and l-alanine. Transcriptome analysis, as well as an adaptive laboratory evolution experiment with the ΔaceE Δpyc strain, revealed the reduction of glucose uptake as a key adaptive measure to enhance growth on glucose-acetate mixtures. Taken together, our results highlight the significant impact of the intracellular CO2/HCO3– pool on metabolic flux distribution, which becomes especially evident in engineered strains exhibiting low endogenous CO2 production rates, as exemplified by PDHC-deficient strains. IMPORTANCE CO2 is a ubiquitous product of cellular metabolism and an essential substrate for carboxylation reactions. The pyruvate dehydrogenase complex (PDHC) catalyzes a central metabolic reaction contributing to the intracellular CO2/HCO3– pool in many organisms. In this study, we used a PDHC-deficient strain of Corynebacterium glutamicum, which additionally lacked pyruvate carboxylase (ΔaceE Δpyc). This strain featured a >15-h lag phase during growth on glucose-acetate mixtures. We used this strain to systematically assess the impact of alterations in the intracellular CO2/HCO3– pool on growth in glucose-acetate medium. Remarkably, all measures enhancing CO2/HCO3– levels successfully restored growth. These results emphasize the strong impact of the intracellular CO2/HCO3– pool on metabolic flux, especially in strains exhibiting low endogenous CO2 production rates.

The Pyruvate Dehydrogenase Complex as a Target for Gene Therapy

2003 ◽  
Vol 3 (3) ◽  
pp. 239-245 ◽  
Author(s):  
Peter Stacpoole ◽  
Renius Owen ◽  
Terence Flotte
Keyword(s):  
Gene Therapy ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Dehydrogenase Complex
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