ABSTRACT In Escherichia coli, phosphoenolpyruvate synthetase (PEPS) catalyzes the conversion of pyruvate to phosphoenolpyruvate (PEP). The enzyme is regulated at four levels: it is regulated at the level of transcription by the carbon source available for growth, by regulation of mRNA stability, by metabolic intermediates, and, by a recently discovered phosphorylation/ dephosphorylation mechanism. This manuscript reviews our current understanding of the four levels of regulation of the peps gene and its gene product and reports on recent advances made in our understanding of the post-translational regulation of the protein. A model is proposed that summarizes the control of pyruvate metabolism in E. coli (and other bacterial species possessing PEP synthetase or pyruvate, orthophosphate dikinase); whether pyruvate is used for the generation of ATP or whether pyruvate is converted to PEP for use in gluconeogenesis, aromatic amino acid synthesis and other anabolic pathways. Finally, we provide some suggestions regarding the use of PEPS in the biotechnology industry based on our understanding of the regulation of the enzyme.
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