The OmpA amino acid residues EVQ are essential for the interaction with the virulence factor PhoN2.

is an intracellular pathogen that deploys an arsenal of virulence factors promoting host cell invasion, intracellular multiplication and intra- and inter-cellular dissemination. We have previously reported that the interaction between apyrase (PhoN2), a periplasmic ATP-diphosphohydrolase, and the C-terminal domain of the outer membrane (OM) protein OmpA is likely required for proper IcsA exposition at the old bacterial pole and thus for full virulence expression of (Scribano et al., 2014). OmpA, that is the major OM protein of Gram-negative bacteria, is a multifaceted protein that plays many different roles both in the OM structural integrity and in the virulence of several pathogens. Here, by using yeast two-hybrid technology and by constructing an 3D model of OmpA from 5a strain M90T, we observed that the OmpA residues EVQ are likely essential for PhoN2-OmpA interaction. The EVQ amino acids are located within a flexible region of the OmpA protein that could represent a scaffold for protein-protein interaction.