title: Designing an Escherichia coli Strain for Phenylalanine Overproduction by Metabolic Engineering.
abstract: The phenylalanine pathway flux is controlled by two types of regulators, those that are specific to the pathway, as well as by global regulators. In order to demonstrate the importance of these global regulators, we first removed the pathway-specific regulators using all possible combinations of gene knockouts and knockins. We found that genes like aroGfbrperformed best individually as well as in combination with other genes, while other genes like tyrA and tyrR worked only in combination with other modifications. Knocking in the tktA gene under a tyrR promoter and knocking out pykF further increased phenylalanine production demonstrating that the supply of precursor via PEP and E4P is also a rate-limiting step. Finally, we tested the role of global regulators on this deregulated pathway and found that Fis overexpression helps in both enhancing and sustaining the flux through this pathway. This work opens up the possibility of using global regulators in synergy with pathway-specific modifications to enhance product yields.
authors.affiliation: School of Biotechnology, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Neetu
authors.initials: N
authors.lastname: Tyagi
authors.affiliation: School of Biotechnology, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Deepti
authors.initials: D
authors.lastname: Saini
authors.affiliation: School of Biotechnology, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Richa
authors.initials: R
authors.lastname: Guleria
authors.affiliation: School of Biotechnology, Jawaharlal Nehru University, New Delhi, India. kjmukherjee@mail.jnu.ac.in.
authors.forename: Krishna Jyoti
authors.initials: KJ
authors.lastname: Mukherjee
mesh_terms: D003198:Computer Simulation; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D024861:Genetic Enhancement / Q000379:methods*; D060847:Metabolic Engineering / Q000379:methods*; D064688:Metabolic Flux Analysis / Q000379:methods; D053858:Metabolic Networks and Pathways / Q000502:physiology; D008954:Models, Biological; D010649:Phenylalanine / Q000096:biosynthesis* / Q000302:isolation & purification; D015854:Up-Regulation / Q000235:genetics
chemical_list: D010649:Phenylalanine
keywords: E. coli; Fis; Metabolic engineering; Phenylalanine; Systems biology