Paracoccus denitrificans and the evolutionary origin of the mitochondrion

It is demonstrated that Paracoccus denitrificans resembles a mitochondrion more closely than do other bacteria, in that it effectively assembles in a single organism those features of the mitochondrial respiratory chain and oxidative phosphorylation which are otherwise distributed at random among most other aerobic bacteria. A feasible evolutionary transition from the plasma membrane of an ancestral aerobic bacterium resembling P. denitrificans to the inner mitochondrial membrane is suggested.