The CreC Regulator of Escherichia coli, a New Target for Metabolic Manipulations.
The CreBC (carbon source-responsive) two-component regulation system of Escherichia coli affects a number of functions, including intermediary carbon catabolism. The impacts of different creC mutations (a ΔcreC mutant and a mutant carrying the constitutive creC510 allele) on bacterial physiology were analyzed in glucose cultures under three oxygen availability conditions. Differences in the amounts of extracellular metabolites produced were observed in the null mutant compared to the wild-type strain and the mutant carrying creC510 and shown to be affected by oxygen availability. The ΔcreC strain secreted more formate, succinate, and acetate but less lactate under low aeration. These metabolic changes were associated with differences in AckA and LdhA activities, both of which were affected by CreC. Measurement of the NAD(P)H/NAD(P)(+) ratios showed that the creC510 strain had a more reduced intracellular redox state, while the opposite was observed for the ΔcreC mutant, particularly under intermediate oxygen availability conditions, indicating that CreC affects redox balance. The null mutant formed more succinate than the wild-type strain under both low aeration and no aeration. Overexpression of the genes encoding phosphoenolpyruvate carboxylase from E. coli and a NADH-forming formate dehydrogenase from Candida boidinii in the ΔcreC mutant further increased the yield of succinate on glucose. Interestingly, the elimination of ackA and adhE did not significantly improve the production of succinate. The diverse metabolic effects of this regulator on the central biochemical network of E. coli make it a good candidate for metabolic-engineering manipulations to enhance the formation of bioproducts, such as succinate.
Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (IQUIBICEN-CONICET), Buenos Aires, Argentina.
Manuel S
MS
Godoy
Systems and Synthetic Biology Program, Spanish National Centre for Biotechnology (CNB-CSIC), Madrid, Spain.
Pablo I
PI
Nikel
Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil.
José G
JG
Cabrera Gomez
Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (IQUIBICEN-CONICET), Buenos Aires, Argentina jul@qb.fcen.uba.ar.
M Julia
http://orcid.org/0000-0002-6130-4740
MJ
Pettinari
D000693:Anaerobiosis; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D005947:Glucose / Q000378:metabolism; D060847:Metabolic Engineering; D009154:Mutation; D009243:NAD / Q000378:metabolism; D009245:NADH Dehydrogenase / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D015202:Protein Engineering; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism*; D019802:Succinic Acid / Q000378:metabolism*
D029968:Escherichia coli Proteins; D009243:NAD; D019802:Succinic Acid; D009245:NADH Dehydrogenase; D011494:Protein Kinases; C066232:CreC protein, E coli; D005947:Glucose; D010100:Oxygen