Distribution of phoP-phoQ, the magnesium transporters mgtA and mgtB, and lipid A modification genes among the insect pathogen Photorhabdus luminescens and recently derived and ancient insect endosymbionts.

Estimated age of association (in million of years) is shown for ancient insect symbionts [58]. “P” indicates that a given sequence was determined to be a pseudogene. ”N. A.” signifies not applicable. Numbers of acidic residues within the acidic patch are displayed for PhoQ homologues. Note also that Candidatus Serratia symbiotica maintains a truncated PhoQ homologue.