This domain is found in the toxin ExoU from Pseudomonas aeruginosa, an effector of the type III secretion system of the bacteria. ExoU is a patatin-like phospholipase that binds to the host membranes and induces cytotoxic effects leading to rapid necrotic cell death. This protein shows four domains: a putative chaperone binding domain. a patatin-like domain (Pfam:PF01734), and two domains that form the membrane localization domain (MLD). This entry represents the C-terminal domain, which folds into a four-helical bundle with a conserved arginine exposed. This residue seems to be essential for localization [1-3].

1: Structure of the type III secretion effector protein ExoU in complex with its chaperone SpcU. Halavaty AS, Borek D, Tyson GH, Veesenmeyer JL, Shuvalova L, Minasov G, Otwinowski Z, Hauser AR, Anderson WF; PLoS One. 2012;7:e49388. PMID:23166655

2: Structural basis of cytotoxicity mediated by the type III secretion toxin ExoU from Pseudomonas aeruginosa. Gendrin C, Contreras-Martel C, Bouillot S, Elsen S, Lemaire D, Skoufias DA, Huber P, Attree I, Dessen A; PLoS Pathog. 2012;8:e1002637. PMID:22496657

3: A novel phosphatidylinositol 4,5-bisphosphate binding domain mediates plasma membrane localization of ExoU and other patatin-like phospholipases. Tyson GH, Halavaty AS, Kim H, Geissler B, Agard M, Satchell KJ, Cho W, Anderson WF, Hauser AR; J Biol Chem. 2015;290:2919-2937. PMID:25505182