title: Synergistic stimulation of EpsE ATP hydrolysis by EpsL and acidic phospholipids.
abstract: EpsE is a cytoplasmic component of the type II secretion system in Vibrio cholerae. Through ATP hydrolysis and an interaction with the cytoplasmic membrane protein EpsL, EpsE supports secretion of cholera toxin across the outer membrane. In this study, we have determined the effect of the cytoplasmic domain of EpsL (cyto-EpsL) and purified phospholipids on the ATPase activity of EpsE. Acidic phospholipids, specifically cardiolipin, bound the copurified EpsE/cyto-EpsL complex and stimulated its ATPase activity 30-130-fold, whereas the activity of EpsE alone was unaffected. Removal of the last 11 residues (residues 243-253) from cyto-EpsL prevented cardiolipin binding as well as stimulation of the ATPase activity of EpsE. Further mutagenesis of the C-terminal region of the EpsL cytoplasmic domain adjacent to the predicted transmembrane helix suggested that this region participates in fine tuning the interaction of EpsE with the cytoplasmic membrane and influences the oligomerization state of EpsE thereby stimulating its ATPase activity and promoting extracellular secretion in V. cholerae.
authors.affiliation: University of Maryland School of Medicine, Department of Medicine, Division of Infectious Diseases, Rockville, MD, USA.
authors.forename: Jodi L
authors.initials: JL
authors.lastname: Camberg
authors.forename: Tanya L
authors.initials: TL
authors.lastname: Johnson
authors.forename: Marcella
authors.initials: M
authors.lastname: Patrick
authors.forename: Jan
authors.initials: J
authors.lastname: Abendroth
authors.forename: Wim G J
authors.initials: WG
authors.lastname: Hol
authors.forename: Maria
authors.initials: M
authors.lastname: Sandkvist
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry / Q000502:physiology*; D002308:Cardiolipins / Q000737:chemistry; D003001:Cloning, Molecular; D003432:Cross-Linking Reagents / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006868:Hydrolysis; D008565:Membrane Proteins / Q000737:chemistry* / Q000502:physiology*; D009154:Mutation; D010743:Phospholipids / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D014734:Vibrio cholerae / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002308:Cardiolipins; D003432:Cross-Linking Reagents; C079398:EpsE protein, Vibrio cholerae; D008565:Membrane Proteins; D010743:Phospholipids; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases