title: Aerobic respiratory chain of Escherichia coli is not allowed to work in fully uncoupled mode.
abstract: 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.
authors: Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia.
authors: Vitaliy B
authors: VB
authors: Borisov
authors: Ranjani
authors: R
authors: Murali
authors: Marina L
authors: ML
authors: Verkhovskaya
authors: Dmitry A
authors: DA
authors: Bloch
authors: Huazhi
authors: H
authors: Han
authors: Robert B
authors: RB
authors: Gennis
authors: Michael I
authors: MI
authors: Verkhovsky
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000332:Aerobiosis; D003573:Cytochrome b Group; D003580:Cytochromes / Q000378:metabolism; D004579:Electron Transport; D045222:Electron Transport Chain Complex Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism; D008564:Membrane Potentials; D008954:Models, Biological; D009243:NAD / Q000378:metabolism; D010088:Oxidoreductases / Q000378:metabolism; D018892:Proton-Motive Force
chemical_list: D003573:Cytochrome b Group; D003580:Cytochromes; D045222:Electron Transport Chain Complex Proteins; D029968:Escherichia coli Proteins; D009243:NAD; D000255:Adenosine Triphosphate; D010088:Oxidoreductases; C040077:cytochrome bd terminal oxidase complex, E coli