RRC ID 4953
Author Bekker M, de Vries S, Ter Beek A, Hellingwerf KJ, de Mattos MJ.
Title Respiration of Escherichia coli can be fully uncoupled via the nonelectrogenic terminal cytochrome bd-II oxidase.
Journal J Bacteriol
Abstract The respiratory chain of Escherichia coli is usually considered a device to conserve energy via the generation of a proton motive force, which subsequently may drive ATP synthesis by the ATP synthetase. It is known that in this system a fixed amount of ATP per oxygen molecule reduced (P/O ratio) is not synthesized due to alternative NADH dehydrogenases and terminal oxidases with different proton pumping stoichiometries. Here we show that P/O ratios can vary much more than previously thought. First, we show that in wild-type E. coli cytochrome bo, cytochrome bd-I, and cytochrome bd-II are the major terminal oxidases; deletion of all of the genes encoding these enzymes results in a fermentative phenotype in the presence of oxygen. Second, we provide evidence that the electron flux through cytochrome bd-II oxidase is significant but does not contribute to the generation of a proton motive force. The kinetics support the view that this system is as an energy-independent system gives the cell metabolic flexibility by uncoupling catabolism from ATP synthesis under non-steady-state conditions. The nonelectrogenic nature of cytochrome bd-II oxidase implies that the respiratory chain can function in a fully uncoupled mode such that ATP synthesis occurs solely by substrate level phosphorylation. As a consequence, the yield with a carbon and energy source can vary five- to sevenfold depending on the electron flux distribution in the respiratory chain. A full understanding and control of this distribution open new avenues for optimization of biotechnological processes.
Volume 191(17)
Pages 5510-7
Published 2009-9-1
DOI 10.1128/JB.00562-09
PII JB.00562-09
PMID 19542282
PMC PMC2725625
MeSH Adenosine Triphosphate / biosynthesis* Cytochrome b Group / genetics Cytochrome b Group / metabolism Cytochromes / genetics Cytochromes / metabolism* Electron Transport Chain Complex Proteins / genetics Electron Transport Chain Complex Proteins / metabolism* Escherichia coli / genetics Escherichia coli / metabolism* Escherichia coli Proteins / genetics Escherichia coli Proteins / metabolism* Fermentation Gene Deletion Oxidoreductases / genetics Oxidoreductases / metabolism* Oxygen Consumption*
IF 3.234
Times Cited 63
Prokaryotes E. coli ME7986(MG1655) ME9062(BW25113)