title: Disruption of a global regulatory gene to enhance central carbon flux into phenylalanine biosynthesis in Escherichia coli.
abstract: Genetic engineering of microbes for commercial metabolite production traditionally has sought to alter the levels and/or intrinsic activities of key enzymes in relevant biosynthetic pathway(s). Microorganisms exploit similar strategies for flux control, but also coordinate flux through sets of related pathways by using global regulatory circuits. We have engineered a global regulatory system of Escherichia coli, Csr (carbon storage regulator), to increase precursor for aromatic amino acid biosynthesis. Disruption of csrA increases gluconeogenesis, decreases glycolysis, and thus elevates phosphoenolpyruvate, a limiting precursor of aromatics. A strain in which the aromatic (shikimate) pathway had been optimized produced twofold more phenylalanine when csrA was disrupted. Overexpression of tktA (transketolase) to increase the other precursor, erythrose-4-phosphate, yielded approximately 1.4-fold enhancement, while both changes were additive. These effects of csrA were not mediated by increasing the regulatory enzymes of phenylalanine biosynthesis. This study introduces the concept of "global metabolic engineering" for second-generation strain improvement.
authors.affiliation: Department of Molecular Biology and Immunology, University of North Texas Health Science Center at Fort Worth, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107-2699, USA.
authors.forename: M
authors.initials: M
authors.lastname: Tatarko
authors.forename: T
authors.initials: T
authors.lastname: Romeo
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005809:Genes, Regulator / Q000235:genetics; D005818:Genetic Engineering / Q000379:methods; D005947:Glucose / Q000378:metabolism; D010649:Phenylalanine / Q000032:analysis / Q000096:biosynthesis*; D010728:Phosphoenolpyruvate / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins; D013403:Sugar Phosphates / Q000096:biosynthesis / Q000378:metabolism; D014174:Transketolase / Q000096:biosynthesis / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C093587:CsrA protein, E coli; D029968:Escherichia coli Proteins; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D013403:Sugar Phosphates; C013469:3-deoxy-D-arabino-heptulosonate-7-phosphate; D010649:Phenylalanine; D010728:Phosphoenolpyruvate; D014174:Transketolase; D005947:Glucose