A PHYLOGENETIC ANALYSIS OF THE CYTOCHROME-B AND CYTOCHROME-C-OXIDASE-I GENES SUPPORTS AN ORIGIN OF MITOCHONDRIA FROM WITHIN THE RICKETTSIACEAE

We have cloned and sequenced the genes encoding cytochrome b (cob) and cytochrome c oxidase subunit I (cox1) from Rickettsia prowazekii, a m ember of the alpha-proteobacteria. The phylogenetic analysis supports the hypothesis that mitochondria are derived from the alpha-proteobact eria and more specifically from within the Rickettsiaceae. We have est imated that the common ancestor of mitochondria and Rickettsiaceae dat es back to more than 1500 million years ago. (C) 1998 Elsevier Science B.V. All rights reserved.