The Experts below are selected from a list of 85341 Experts worldwide ranked by ideXlab platform
Milton H. Saier - One of the best experts on this subject based on the ideXlab platform.
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Identification of a phosphoenolpyruvate:Fructose phosphotransferase system (Fructose-1-phosphate forming) in Listeria monocytogenes.
Journal of bacteriology, 1993Co-Authors: W J Mitchell, Jonathan Reizer, Christopher D. Herring, C Hoischen, Milton H. SaierAbstract:Listeria monocytogenes is a gram-positive bacterium whose carbohydrate metabolic pathways are poorly understood. We provide evidence for an inducible phosphoenolpyruvate (PEP):Fructose phosphotransferase system (PTS) in this pathogen. The system consists of enzyme I, HPr, and a Fructose-specific enzyme II complex which generates Fructose-1-phosphate as the cytoplasmic product of the PTS-catalyzed vectorial phosphorylation reaction. Fructose-1-phosphate kinase then converts the product of the PTS reaction to Fructose-1,6-bisphosphate. HPr was shown to be phosphorylated by [32P]PEP and enzyme I as well as by [32P]ATP and a Fructose-1,6-bisphosphate-activated HPr kinase like those found in other gram-positive bacteria. Enzyme I, HPr, and the enzyme II complex of the Listeria PTS exhibit enzymatic cross-reactivity with PTS enzyme constituents from Bacillus subtilis and Staphylococcus aureus.
Peter Schonheit - One of the best experts on this subject based on the ideXlab platform.
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Fructose degradation in the haloarchaeon haloferax volcanii involves a bacterial type phosphoenolpyruvate dependent phosphotransferase system Fructose 1 phosphate kinase and class ii Fructose 1 6 bisphosphate aldolase
Journal of Bacteriology, 2012Co-Authors: Andreas Pickl, Ulrike Johnsen, Peter SchonheitAbstract:The halophilic archaeon Haloferax volcanii utilizes Fructose as a sole carbon and energy source. Genes and enzymes involved in Fructose uptake and degradation were identified by transcriptional analyses, deletion mutant experiments, and enzyme characterization. During growth on Fructose, the gene cluster HVO_1495 to HVO_1499, encoding homologs of the five bacterial phosphotransferase system (PTS) components enzyme IIB (EIIB), enzyme I (EI), histidine protein (HPr), EIIA, and EIIC, was highly upregulated as a cotranscript. The in-frame deletion of HVO_1499, designated ptfC (ptf stands for phosphotransferase system for Fructose) and encoding the putative Fructose-specific membrane component EIIC, resulted in a loss of growth on Fructose, which could be recovered by complementation in trans. Transcripts of HVO_1500 (pfkB) and HVO_1494 (fba), encoding putative Fructose-1-phosphate kinase (1-PFK) and Fructose-1,6-bisphosphate aldolase (FBA), respectively, as well as 1-PFK and FBA activities were specifically upregulated in Fructose-grown cells. pfkB and fba knockout mutants did not grow on Fructose, whereas growth on glucose was not inhibited, indicating the functional involvement of both enzymes in Fructose catabolism. Recombinant 1-PFK and FBA obtained after homologous overexpression were characterized as having kinetic properties indicative of functional 1-PFK and a class II type FBA. From these data, we conclude that Fructose uptake in H. volcanii involves a Fructose-specific PTS generating Fructose-1-phosphate, which is further converted via Fructose-1,6-bisphosphate to triose phosphates by 1-PFK and FBA. This is the first report of the functional involvement of a bacterial-like PTS and of class II FBA in the sugar metabolism of archaea.
Emile Van Schaftingen - One of the best experts on this subject based on the ideXlab platform.
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Overexpression and purification of Fructose-1-phosphate kinase from Escherichia coli: application to the assay of Fructose 1-phosphate.
Protein expression and purification, 2000Co-Authors: Maria Veiga Da Cunha, A. Hoyoux, Emile Van SchaftingenAbstract:Fructose 1-phosphate is a metabolite that plays a regulatory role in liver and is best measured using an assay based on its conversion to Fructose 1,6-bisphosphate by a bacterial Fructose-1-phosphate kinase (Fru1PK). The open reading frame encoding Escherichia coli Fru1PK has been introduced in an expression plasmid (pET3a) based on the T7 promoter-driven system, which was used to overexpress the enzyme. The conditions for the production of soluble Fru1PK were optimized. The purification procedure used involved ammonium sulfate precipitation and chromatography on DEAE-Sepharose and was aimed mostly at stabilizing the enzyme and at freeing Fru1PK from bacterial contaminants that could interfere in the Fructose 1-phosphate assay. From a 1-liter culture, more than 50 mg protein is obtained. This preparation can be used in an enzymatic assay that measures specifically Fructose 1-phosphate in tissue extracts.
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Inhibition of phosphomannose isomerase by Fructose 1-phosphate: an explanation for defective N-glycosylation in hereditary Fructose intolerance.
Pediatric research, 1996Co-Authors: Jaak Jaeken, Michel Pirard, Maciej Adamowicz, Ewa Pronicka, Emile Van SchaftingenAbstract:Isoelectrofocusing of serum sialotransferrins from patients with untreated hereditary Fructose intolerance (HFI) shows a cathodal shift similar to that in carbohydrate-deficient glycoprotein (CDG) syndrome type I and in untreated galactosemia. This report is on serum lysosomal enzyme abnormalities in untreated HFI that are identical to those found in CDG syndrome type I but different from those in untreated galactosemia. CDG syndrome type I is due to phosphomannomutase deficiency, a defect in the early glycosylation pathway. It was found that Fructose 1-phosphate is a potent competitive inhibitor (Ki congruent to 40 microM) of phosphomannose isomerase (EC 5.3.1.8), the first enzyme of the N-glycosylation pathway thus explaining the N-glycosylation disturbances in HFI.
W J Mitchell - One of the best experts on this subject based on the ideXlab platform.
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Identification of a phosphoenolpyruvate:Fructose phosphotransferase system (Fructose-1-phosphate forming) in Listeria monocytogenes.
Journal of bacteriology, 1993Co-Authors: W J Mitchell, Jonathan Reizer, Christopher D. Herring, C Hoischen, Milton H. SaierAbstract:Listeria monocytogenes is a gram-positive bacterium whose carbohydrate metabolic pathways are poorly understood. We provide evidence for an inducible phosphoenolpyruvate (PEP):Fructose phosphotransferase system (PTS) in this pathogen. The system consists of enzyme I, HPr, and a Fructose-specific enzyme II complex which generates Fructose-1-phosphate as the cytoplasmic product of the PTS-catalyzed vectorial phosphorylation reaction. Fructose-1-phosphate kinase then converts the product of the PTS reaction to Fructose-1,6-bisphosphate. HPr was shown to be phosphorylated by [32P]PEP and enzyme I as well as by [32P]ATP and a Fructose-1,6-bisphosphate-activated HPr kinase like those found in other gram-positive bacteria. Enzyme I, HPr, and the enzyme II complex of the Listeria PTS exhibit enzymatic cross-reactivity with PTS enzyme constituents from Bacillus subtilis and Staphylococcus aureus.
E Van Schaftingen - One of the best experts on this subject based on the ideXlab platform.
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binding of sorbitol 6 phosphate and of Fructose 1 phosphate to the regulatory protein of liver glucokinase
Biochemical Journal, 1992Co-Authors: Annick Vandercammen, Michel Detheux, E Van SchaftingenAbstract:Using a binding assay in which the ligand-protein complex is separated from free ligand by precipitation with poly(ethylene glycol) 6000, we found that the regulatory protein of rat liver glucokinase bound close to 1 mol of radiolabelled sorbitol 6-phosphate, a negative effector, or of Fructose 1-phosphate, a positive effector, per mol of regulatory protein. Scatchard plots were linear, the dissociation constant being 0.3 microM for both phosphate esters. Sorbitol 6-phosphate and Fructose 1-phosphate competed with each other for the binding. Competition was also observed with psicose 1-phosphate, ribitol 5-phosphate, arabitol 5-phosphate and 3-phosphoglycerate, all of which are known to affect the inhibition exerted by the regulatory protein. At a concentration of 10%, poly(ethylene glycol) 6000 decreased the concentration of regulatory protein causing 50% inhibition to a larger extent in the absence (12-fold) than in the presence (3-fold) of a saturating concentration of Fructose 6-phosphate, another negative effector. Furthermore, it increased by about 3-fold the apparent affinity for inhibitory phosphate esters, indicating that it induced conformational changes of the regulatory protein.
