First Steps Towards Organelle

The previously described chimeric organism and rickettsia-like endosymbiont may have met in a microaerobic environment rich in antibiotics. Finding that all species of Rickettsiaceae-Anaplasmataceae characterized to date possess ValRS of an archaeal genre, unlike free-living a-Proteobacteria which have typically proteobacterial enzyme (Emelyanov 2003a), may partially support this idea. The most parsimonious explanation of this finding is 

In contrast, the immediate ancestor of the organelle lost the ability to escape from pro-eukaryotic host, with its proliferation having been forced to keep pace with host cell division. The establishment of highly precise and 

It was earlier hypothesized that the AAC had been invented either by chlamydiae with subsequent LGT to rickettsiae or by rickettsiae, and was physically but not functionally transferred from the latter to the genome of an amitochondriate host. Similarly to Coxl, also containing 12 transmembrane domains incompatible with import, rickettsial AAC could not be imported into mitochondria, but was later recruited to chloroplasts in a plant lineage (Emelyanov 2001b). Therefore, unrelated mitochondrial AAC - a member of the mitochondrial carrier family proteins containing six transmembrane 

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In conclusion the E. coli ribosome is the first cell organelle for which an understanding at the molecular level of both structure and function can be expected. An essential step towards this very attractive goal is a thorough investigation of the primary structures of all ribosomal components. 

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