The Experts below are selected from a list of 123 Experts worldwide ranked by ideXlab platform
Mark I. Donnelly - One of the best experts on this subject based on the ideXlab platform.
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Enhanced production of succinic acid by overexpression of Phosphoenolpyruvate carboxylase in \textit{{Escherichia coli}}.
Appl. Environ. Microbiol., 1996Co-Authors: Cynthia Sanville Millard, Y P Chao, James C. Liao, Mark I. DonnellyAbstract:Fermentative production of succinic acid from glucose by Escherichia coli was significantly increased by overexpression of Phosphoenolpyruvate carboxylase. In contrast, overexpression of Phosphoenolpyruvate carboxykinase had no effect. Under optimized conditions, induction of the carboxylase resulted in a 3.5-fold increase in the concentration of succinic acid, making succinic acid the major fermentation product by weight.
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Enhanced production of succinic acid by overexpression of Phosphoenolpyruvate carboxylase in Escherichia coli.
Applied and environmental microbiology, 1996Co-Authors: Cynthia Sanville Millard, Y P Chao, James C. Liao, Mark I. DonnellyAbstract:Fermentative production of succinic acid from glucose by Escherichia coli was significantly increased by overexpression of Phosphoenolpyruvate carboxylase. In contrast, overexpression of Phosphoenolpyruvate carboxykinase had no effect. Under optimized conditions, induction of the carboxylase resulted in a 3.5-fold increase in the concentration of succinic acid, making succinic acid the major fermentation product by weight.
Y P Chao - One of the best experts on this subject based on the ideXlab platform.
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Enhanced production of succinic acid by overexpression of Phosphoenolpyruvate carboxylase in \textit{{Escherichia coli}}.
Appl. Environ. Microbiol., 1996Co-Authors: Cynthia Sanville Millard, Y P Chao, James C. Liao, Mark I. DonnellyAbstract:Fermentative production of succinic acid from glucose by Escherichia coli was significantly increased by overexpression of Phosphoenolpyruvate carboxylase. In contrast, overexpression of Phosphoenolpyruvate carboxykinase had no effect. Under optimized conditions, induction of the carboxylase resulted in a 3.5-fold increase in the concentration of succinic acid, making succinic acid the major fermentation product by weight.
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Enhanced production of succinic acid by overexpression of Phosphoenolpyruvate carboxylase in Escherichia coli.
Applied and environmental microbiology, 1996Co-Authors: Cynthia Sanville Millard, Y P Chao, James C. Liao, Mark I. DonnellyAbstract:Fermentative production of succinic acid from glucose by Escherichia coli was significantly increased by overexpression of Phosphoenolpyruvate carboxylase. In contrast, overexpression of Phosphoenolpyruvate carboxykinase had no effect. Under optimized conditions, induction of the carboxylase resulted in a 3.5-fold increase in the concentration of succinic acid, making succinic acid the major fermentation product by weight.
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Alteration of growth yield by overexpression of Phosphoenolpyruvate carboxylase and Phosphoenolpyruvate carboxykinase in Escherichia coli.
Applied and Environmental Microbiology, 1993Co-Authors: Y P Chao, James C. LiaoAbstract:Phosphoenolpyruvate and oxaloacetate are key intermediates at the junction between catabolism and biosynthesis. Alteration of carbon flow at these branch points will affect the growth yield and the formation of products. We attempted to modulate the metabolic flow between Phosphoenolpyruvate and oxaloacetate by overexpressing Phosphoenolpyruvate carboxylase and Phosphoenolpyruvate carboxykinase from a multicopy plasmid under the control of the tac promoter. It was found that overexpression of Phosphoenolpyruvate carboxylase decreased the rates of glucose consumption and organic acid excretion, but the growth and respiration rates remained unchanged. Consequently, the growth yield on glucose was improved. This result indicates that the wild-type level of Phosphoenolpyruvate carboxylase is not optimal for the most efficient glucose utilization in batch cultures. On the other hand, overexpression of Phosphoenolpyruvate carboxykinase increased glucose consumption and decreased oxygen consumption relative to those levels required for growth. Therefore, the growth yield on glucose was reduced because of a higher rate of fermentation product excretion. These data provide useful insights into the regulation of central metabolism and facilitate further manipulation of pathways for metabolite production.
Hugh G. Nimmo - One of the best experts on this subject based on the ideXlab platform.
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Characterisation of a Phosphoenolpyruvate carboxylase kinase gene from Sorghum
Science Access, 2001Co-Authors: James Hartwell, Gareth I. Jenkins, Hugh G. NimmoAbstract:Light-induced phosphorylation of Phosphoenolpyruvate carboxylase plays an important role in C4 photosynthesis. It reduces the sensitivity of Phosphoenolpyruvate carboxylase to malate and thereby allows this enzyme to fix bicarbonate even in the presence of a high concentration of malate in the mesophyll cell cytosol. Previous work has shown that light causes an increase in the activity of Phosphoenolpyruvate carboxylase kinase in a process involving protein synthesis. Phosphoenolpyruvate carboxylase kinase genes have been cloned from a range of C3 and CAM species, but not so far from C4 species. We have identified a Phosphoenolpyruvate carboxylase cDNA from the C4 plant Sorghum bicolor. It encodes a 307 residue protein of predicted Mr 32524, which, like other Phosphoenolpyruvate carboxylase kinases, comprises a protein kinase catalytic domain with minimal extensions at the N- and C-terminal ends. However, relative to other Phosphoenolpyruvate carboxylase kinases, the Sorghum enzyme contains an acidic 23-residue insert just after the catalytic loop. Structure prediction suggests that this insert would be exposed at the surface of the protein. Using in vitro transcription and translation, we have demonstrated that the protein encoded by this cDNA has high Phosphoenolpyruvate carboxylase kinase activity. This appears to be the first report of a cloned Phosphoenolpyruvate carboxylase kinase from a C4 plant. Data on the expression of the gene in response to light and to cycloheximide will be presented.
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The regulation of Phosphoenolpyruvate carboxylase in CAM plants
Trends in Plant Science, 2000Co-Authors: Hugh G. NimmoAbstract:Phosphoenolpyruvate carboxylase catalyses the primary assimilation of CO2in Crassulacean acid metabolism plants. It is activated by phosphorylation, and this plays a major role in setting the day-night pattern of metabolism in these plants. The key factor that controls the phosphorylation state of Phosphoenolpyruvate carboxylase is the activity of Phosphoenolpyruvate carboxylase kinase. Recent work on Crassulacean acid metabolism plants has established this enzyme as a novel protein kinase and has provided new insights into the regulation of protein phosphorylation. Phosphoenolpyruvate carboxylase kinase is controlled by synthesis and degradation in response to a circadian oscillator. The circadian control of Phosphoenolpyruvate carboxylase kinase can be overridden by changes in metabolite levels. The primary effect of the circadian oscillator in this system may be at the level of the tonoplast, and changes in kinase expression may be secondary to circadian changes in the concentration of a metabolite, perhaps cytosolic malate.
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Phosphoenolpyruvate carboxylase kinase is a novel protein kinase regulated at the level of expression
Plant Journal, 1999Co-Authors: James Hartwell, Gareth I. Jenkins, Aideen Gill, Gillian A Nimmo, Malcolm B Wilkins, Hugh G. NimmoAbstract:Summary Phosphorylation of Phosphoenolpyruvate carboxylase plays a key role in the control of plant metabolism. Phosphoenolpyruvate carboxylase kinase is a Ca2+-independent enzyme that is activated by a process involving protein synthesis in response to a range of signals in different plant tissues. The component whose synthesis is required for activation has not previously been identified, nor has the kinase been characterised at a molecular level. We report the cloning of Phosphoenolpyruvate carboxylase kinase from the Crassulacean Acid Metabolism plant Kalanchoe fedtschenkoi and the C3 plant Arabidopsis thaliana. Surprisingly, Phosphoenolpyruvate carboxylase kinase is a member of the Ca2+/calmodulin-regulated group of protein kinases. However, it lacks the auto-inhibitory region and EF hands of plant Ca2+-dependent protein kinases, explaining its Ca2+-independence. Its sequence is novel in that it comprises only a protein kinase catalytic domain with no regulatory regions; it appears to be the smallest known protein kinase. In K. fedtschenkoi, the abundance of Phosphoenolpyruvate carboxylase kinase transcripts increases during leaf development. The transcript level in mature leaves is very low during the photoperiod, reaches a peak in the middle of the dark period and correlates with kinase activity. It exhibits a circadian oscillation in constant conditions. Protein kinases are typically regulated by second messengers, phosphorylation or protein/protein interactions. Phosphoenolpyruvate carboxylase kinase is an exception to this general rule, being controlled only at the level of expression. In K. fedtschenkoi, its expression is controlled both developmentally and by a circadian oscillator.
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bryophyllum fedtschenkoi protein phosphatase type 2a can dephosphorylate Phosphoenolpyruvate carboxylase
FEBS Letters, 1990Co-Authors: P J Carter, Hugh G. Nimmo, Charles A Fewson, Malcolm B WilkinsAbstract:Phosphoenolpyruvate carboxylase, which catalyses the nocturnal fixation of CO2 in Crassulacean acid metabolism (CAM) plants, is regulated by reversible phosphorylation. The phosphorylated ‘night’ form of the enzyme is ten-fold less sensitive to inhibition by malate than is the dephosphorylated ‘day’ form. The Phosphoenolpyruvate carboxylase of the CAM plant Bryophyllum fedtschenkoi can be dephosphorylated by rabbit muscle protein phosphatase type 2A but not by type 1. B. fedtschenkoi leaves contain protein phosphatase activity that can dephosphorylate Phosphoenolpyruvate carboxylase. Inhibitor studies show that this enzyme is a type 2A protein phosphatase.
Cynthia Sanville Millard - One of the best experts on this subject based on the ideXlab platform.
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Enhanced production of succinic acid by overexpression of Phosphoenolpyruvate carboxylase in \textit{{Escherichia coli}}.
Appl. Environ. Microbiol., 1996Co-Authors: Cynthia Sanville Millard, Y P Chao, James C. Liao, Mark I. DonnellyAbstract:Fermentative production of succinic acid from glucose by Escherichia coli was significantly increased by overexpression of Phosphoenolpyruvate carboxylase. In contrast, overexpression of Phosphoenolpyruvate carboxykinase had no effect. Under optimized conditions, induction of the carboxylase resulted in a 3.5-fold increase in the concentration of succinic acid, making succinic acid the major fermentation product by weight.
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Enhanced production of succinic acid by overexpression of Phosphoenolpyruvate carboxylase in Escherichia coli.
Applied and environmental microbiology, 1996Co-Authors: Cynthia Sanville Millard, Y P Chao, James C. Liao, Mark I. DonnellyAbstract:Fermentative production of succinic acid from glucose by Escherichia coli was significantly increased by overexpression of Phosphoenolpyruvate carboxylase. In contrast, overexpression of Phosphoenolpyruvate carboxykinase had no effect. Under optimized conditions, induction of the carboxylase resulted in a 3.5-fold increase in the concentration of succinic acid, making succinic acid the major fermentation product by weight.
J. Gregory Zeikus - One of the best experts on this subject based on the ideXlab platform.
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Effect of Overexpression of Actinobacillus succinogenes Phosphoenolpyruvate Carboxykinase on Succinate Production in Escherichia coli
Applied and Environmental Microbiology, 2004Co-Authors: Pil Kim, Maris Laivenieks, Claire Vieille, J. Gregory ZeikusAbstract:Succinate fermentation was investigated in Escherichia coli strains overexpressing Actinobacillus succinogenes Phosphoenolpyruvate carboxykinase (PEPCK). In E. coli K-12, PEPCK overexpression had no effect on succinate fermentation. In contrast, in the Phosphoenolpyruvate carboxylase mutant E. coli strain K-12 ppc::kan, PEPCK overexpression increased succinate production 6.5-fold.
