The aerobic respiratory chain of Escherichia coli couples the oxidation of organic substrates, such as succinate, to the generation of a proton motive force across the cytoplasmic membrane. The mechanism by which this is accomplished is quite different than found in the mitochondrial respiratory system, as predicted by D. Keilin1 nearly 50 years ago. Aerobically grown E. coli has no cytochrome c, and no equivalent to the mitochondrial Complex III (bc1 complex) or Complex IV (cytochrome c oxidase). Instead, two enzymes in the E. coli cytoplasmic membrane, the cytochrome o and cytochrome d complexes, oxidize ubiquinol and directly reduce molecular oxygen to water, concomitantly generating an electrochemical proton gradient across the membrane.
ASJC Scopus subject areas
- Molecular Biology