H-Translocating Membrane-Bound Pyrophosphatase from Fuels Cells via an Alternative Pathway for Energy Generation.

Inorganic pyrophosphatases (PPases) catalyze an essential reaction, namely, the hydrolysis of PP, which is formed in large quantities as a side product of numerous cellular reactions. In the majority of living species, PP hydrolysis is carried out by soluble cytoplasmic PPase (S-PPases) with the released energy dissipated in the form of heat. In part of this energy can be conserved by proton-pumping pyrophosphatase (H-PPase) in the form of a proton electrochemical gradient for further ATP synthesis. Here, the codon-harmonized gene encoding H-PPase was expressed in the chromosome. We demonstrate, for the first time, that H-PPase complements the essential native S-PPase in cells. C-MFA confirmed that replacing native PPase to H-PPase leads to the re-distribution of carbon fluxes; a statistically significant 36% decrease in tricarboxylic acid (TCA) cycle fluxes was found compared with wild-type . MG1655. Such a flux re-distribution can indicate the presence of an additional method for energy generation (e.g., ATP), which can be useful for the microbiological production of a number of compounds, the biosynthesis of which requires the consumption of ATP.