Faculty Collaboration Database

Interactions of the effector ExoU from Pseudomonas aeruginosa with short-chain phosphatidylinositides provide insights into ExoU targeting to host membranes. J Biol Chem 2019 Dec 13;294(50):19012-19021

Date

10/31/2019

Pubmed ID

31662432

Pubmed Central ID

PMC6916483

DOI

10.1074/jbc.RA119.010278

Scopus ID

2-s2.0-85076501851 (requires institutional sign-in at Scopus site)   10 Citations

Abstract

Pseudomonas aeruginosa is an opportunistic multidrug-resistant pathogen and a common cause of infection in cystic fibrosis and ventilator-associated pneumonia and in burn and wound patients. P. aeruginosa uses its type III secretion system to secrete various effector proteins directly into mammalian host cells. ExoU is a potent type III secretion system effector that, after secretion, localizes to the inner cytoplasmic membrane of eukaryotic cells, where it exerts its phospholipase A2 activity upon interacting with ubiquitin and/or ubiquitinated proteins. In this study, we used site-directed spin-labeling electron paramagnetic resonance spectroscopy to examine the interaction of ExoU with soluble analogs of phosphatidylinositol (4,5)-bisphosphate (PI(4,5)P₂). We found that dioctanoyl PI(4,5)P₂ binds to and induces conformational changes in a C-terminal four-helix bundle (4HB) domain of ExoU implicated previously in membrane binding. Other soluble phosphoinositides also interacted with the 4HB but less effectively. Molecular modeling and ligand docking studies indicated the potential for numerous hydrogen bond interactions within and between interhelical loops of the 4HB and suggested several potential interaction sites for PI(4,5)P₂ Site-directed mutagenesis experiments confirmed that the side chains of Gln-623 and Arg-661 play important roles in mediating PI(4,5)P₂-induced conformational changes in ExoU. These results support a mechanism in which direct interactions with phosphatidylinositol-containing lipids play an essential role in targeting ExoU to host membrane bilayers. Molecules or peptides that block this interaction may prove useful in preventing the cytotoxic effects of ExoU to mitigate the virulence of P. aeruginosa strains that express this potent phospholipase toxin.

Author List

Springer TI, Reid TE, Gies SL, Feix JB

Author

Jimmy B. Feix PhD Professor in the Biophysics department at Medical College of Wisconsin

MESH terms used to index this publication - Major topics in bold

Animals
Bacterial Proteins
Cytoplasm
Eukaryotic Cells
Humans
Intracellular Membranes
Models, Molecular
Phosphatidylinositols
Phospholipases
Recombinant Proteins