Presence in Legionella pneumophila of a mammalian-like mitochondrial permeability transition pore?

The genome of Legionella pneumophila reveals the presence of a large number of genes coding for eukaryotic-like proteins. By using database searches and homology investigations, we identified three proteins in L. pneumophila whose sequences share similarities with that of eukaryotic polypeptides (lpg0211, lpg1974 and lpg1982). In eukaryotes, the corresponding proteins (PBR, peripheral benzodiazepine receptor; VDAC, voltage-dependant anion channel; and CypD, cyclophilin D) participate in the formation of the mammalian mitochondrial permeability transition pore (MPTP), a complex involved in cell apoptosis. Intriguingly, the presence of these proteins has never been reported in the same bacterium and constitutes, up to now, a unique feature of L. pneumophila. In Legionella, we hypothesize that these proteins are recruited in a multiprotein complex close to the MPTP that may regulate intracellular survival and/or proliferation.