On the Question of the Metabolic Costs of the Main Metabolic Precursors in Escherichia coli

Abstract

The term metabolic cost (MС) is often used for assessment of energy consumption in the biosynthesis of various substances under different growth conditions or by different cell types. The MC of the metabolite is calculated according to a specified algorithm in universal ~P units, multiples of ATP molecules hydrolyzed to ADP and inorganic phosphate. Our analysis of the published data showed that the interpretation of the MC concept and the algorithms for its calculation, proposed by different authors, differ significantly. Since the MС is often considered in connection with system-level tasks, such as the metabolic flux analysis and the natural selection mechanisms, it seems appropriate to characterize this concept in detail. In this work, the term MС was clearly defined and used to calculate the energy consumption for the synthesis of 13 metabolic precursors of Escherichia coli biomass based on the modern model of the central metabolism of this bacterium. It was found that the MC, expressed in units of stored or hydrolyzed ATP molecules (~P), depends on the characteristics of the metabolism of an individual organism, its culturing conditions, and the P/O ratio, which characterizes the number of ATP molecules formed during the transfer of one electron pair to one oxygen atom in oxidative phosphorylation.