Open AccessEnzyme I facilitates reverse flux from pyruvate to phosphoenolpyruvate in Escherichia coli
Author(s) -
Christopher P. Long,
Jennifer Au,
Nicholas R. Sandoval,
Nikodimos A. Gebreselassie,
Maciek R. Antoniewicz
Publication year - 2017
Publication title -
nature communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.559
H-Index - 365
ISSN - 2041-1723
DOI - 10.1038/ncomms14316
Subject(s) - phosphoenolpyruvate carboxykinase , escherichia coli , flux (metallurgy) , enzyme , chemistry , escherichia coli proteins , biochemistry , biology , gene , organic chemistry
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 use 13 C 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 .