Phylogenic analysis of rickettsial patatin-like protein with conserved phospholipase A2 active sites.

Genome analysis of Rickettsia felis highlighted the presence of three patatin-like protein (PLP) genes (pat1, pat2A, and pat2B), whereas only one PLP gene (pat1) is found in the other sequenced rickettsial genomes. Here, we aligned the rickettsial PLPs with characterized patatins from plants and found that they possess all the conserved amino acid residues identified as important for phospholipase A(2) activity. We also carried out a phylogenic analysis of the rickettsial PLPs together with bacterial and eukaryotic homologs. The phylogeny of the rickettsial Pat1 proteins is in conflict with the currently recognized Rickettsia phylogeny. Possible scenarios that might explain this incongruence are discussed and involve either gene conversion or gene duplication events.