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

作者：Borisov Vitaliy B; Murali Ranjani; Verkhovskaya Marina L; Bloch Dmitry A; Han Huazhi; Gennis Robert B; Verkhovsky Michael I^*

来源：Proceedings of the National Academy of Sciences of the United States of America, 2011, 108(42): 17320-17324.

DOI：10.1073/pnas.1108217108

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, bo3 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.

• 出版日期2011-10-18