Aerobic respiratory chain of Escherichia coli is not allowed to work in fully uncoupled mode

Vitaliy B. Borisov, Ranjani Murali, Marina L. Verkhovskaya, Dmitry A. Bloch, Huazhi Han, Robert B. Gennis, Michael I. Verkhovsky

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Escherichia coli is known to couple aerobic respiratory catabolism to ATP synthesis by virtue of the primary generators of the proton motive force - NADH dehydrogenase I, cytochrome bo 3, and cytochrome bd-I. An E. coli mutant deficient in NADH dehydrogenase I, bo 3 and bd-I can, nevertheless, grow aerobically on nonfermentable substrates, although its sole terminal oxidase cytochrome bd-II has been reported to be nonelectrogenic. In the current work, the ability of cytochrome bd-II to generate a proton motive force is reexamined. Absorption and fluorescence spectroscopy and oxygen pulse methods show that in the steady-state, cytochrome bd-II does generate a proton motive force with a H +/e - ratio of 0.94 ± 0.18. This proton motive force is sufficient to drive ATP synthesis and transport of nutrients. Microsecond time-resolved, single-turnover electrometry shows that the molecular mechanism of generating the proton motive force is identical to that in cytochrome bd-I. The ability to induce cytochrome bd-II biosynthesis allows E. coli to remain energetically competent under a variety of environmental conditions.

Original languageEnglish (US)
Pages (from-to)17320-17324
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number42
StatePublished - Oct 18 2011

ASJC Scopus subject areas

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