The ABC transporter operon. (A) An operon encoding the ABC transporter was present in both P. acanthamoebae and L. drancourtii. (B, C, D and E) A bayesian tree of each orthologous protein (ID 127, 128, 129, and 130) encoded in the operon and their 10 best BLAST hits, restricted to one hit per bacterial genus. Sequences retrieved using L. drancourtii or P. acanthamoebae as the query in a BLAST homology search are tagged with an LLAP or PAH prefix, respectively. Sequences belonging to the best BLAST hit for both orthologues harbor both prefixes. All of the proteins encoded for in the operon exhibit a similar phylogenetic tree, which shows a clustering of P. acanthamoebae and L. drancourtii, thereby supporting the hypothesis of a single transfer event for all four genes.