The CreC regulator of Escherichia coli, a new target for metabolic manipulations

GODOY, MANUEL SANTIAGO ; NIKEL, PABLO IVAN; CABRERA GOMEZ, JOSÉ GREGORIO; PETTINARI, MARÍA JULIA

APPLIED AND ENVIRONMENTAL MICROBIOLOGY

AMER SOC MICROBIOLOGY

Lugar: Washington; Año: 2015

0099-2240

The CreBC (carbon source responsive) two-component regulation system of Escherichia coli affects a number of functions, including intermediary carbon catabolism. The impact of different creC mutations (a ΔcreC mutant and a mutant carrying the constitutive creC510 allele) on bacterial physiology was 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 in low aeration. These metabolic changes were associated to 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 at intermediate oxygen availability conditions, indicating that CreC affects redox balance. The null mutant formed more succinate than the wild-type strain in both low aeration and no aeration. Over42 expression of the genes encoding phosphoenolpyruvate carboxylase from E. coli and a NADH43 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 improve significantly 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.