title: Enzyme I facilitates reverse flux from pyruvate to phosphoenolpyruvate in Escherichia coli.
abstract: The bacterial phosphoenolpyruvate-carbohydrate phosphotransferase system (PTS) consists of cascading phosphotransferases that couple the simultaneous import and phosphorylation of a variety of sugars to the glycolytic conversion of phosphoenolpyruvate (PEP) to pyruvate. As the primary route of glucose uptake in E. coli, the PTS plays a key role in regulating central carbon metabolism and carbon catabolite repression, and is a frequent target of metabolic engineering interventions. Here we show that Enzyme I, the terminal phosphotransferase responsible for the conversion of PEP to pyruvate, is responsible for a significant in vivo flux in the reverse direction (pyruvate to PEP) during both gluconeogenic and glycolytic growth. We use13C alanine tracers to quantify this back-flux in single and double knockouts of genes relating to PEP synthetase and PTS components. Our findings are relevant to metabolic engineering design and add to our understanding of gene-reaction connectivity in E. coli.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark Delaware 19716, USA.
authors.forename: Christopher P
authors.identifier: 0000-0003-1007-417X
authors.initials: CP
authors.lastname: Long
authors.affiliation: Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark Delaware 19716, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Au
authors.affiliation: Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark Delaware 19716, USA.
authors.forename: Nicholas R
authors.initials: NR
authors.lastname: Sandoval
authors.affiliation: Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark Delaware 19716, USA.
authors.forename: Nikodimos A
authors.initials: NA
authors.lastname: Gebreselassie
authors.affiliation: Department of Chemical and Biomolecular Engineering, Metabolic Engineering and Systems Biology Laboratory, University of Delaware, Newark Delaware 19716, USA.
authors.forename: Maciek R
authors.initials: MR
authors.lastname: Antoniewicz
mesh_terms: D050260:Carbohydrate Metabolism; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D055786:Gene Knockout Techniques; D005798:Genes, Bacterial / Q000235:genetics; D005947:Glucose / Q000378:metabolism; D060847:Metabolic Engineering / Q000379:methods; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism*; D010728:Phosphoenolpyruvate / Q000378:metabolism*; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D019289:Pyruvic Acid / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D009004:Monosaccharide Transport Proteins; D010728:Phosphoenolpyruvate; D019289:Pyruvic Acid; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C022358:mannitol PTS permease, E coli; D005947:Glucose