title: Evf, a virulence factor produced by the Drosophila pathogen Erwinia carotovora, is an S-palmitoylated protein with a new fold that binds to lipid vesicles.
abstract: Erwinia carotovora are phytopathogenic Gram-negative bacteria of agronomic interest as these bacteria are responsible for fruit soft rot and use insects as dissemination vectors. The Erwinia carotovora carotovora strain 15 (Ecc15) is capable of persisting in the Drosophila gut by the sole action of one protein, Erwinia virulence factor (Evf). However, the precise function of Evf is elusive, and its sequence does not provide any indication as to its biochemical function. We have solved the 2.0-angstroms crystal structure of Evf and found a protein with a complex topology and a novel fold. The structure of Evf confirms that Evf is unlike any virulence factors known to date. Most remarkably, we identified palmitoic acid covalently bound to the totally conserved Cys209, which provides important clues as to the function of Evf. Mutation of the palmitoic binding cysteine leads to a loss of virulence, proving that palmitoylation is at the heart of Evf infectivity and may be a membrane anchoring signal. Fluorescence studies of the sole tryptophan residue (Trp94) demonstrated that Evf was indeed able to bind to model membranes containing negatively charged phospholipids and to promote their aggregation.
authors.affiliation: Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Université Paris-Sud, UMR8619-CNRS, IFR115, F-91405 Orsay, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Quevillon-Cheruel
authors.forename: Nicolas
authors.initials: N
authors.lastname: Leulliot
authors.forename: Carlos Acosta
authors.initials: CA
authors.lastname: Muniz
authors.forename: Michel
authors.initials: M
authors.lastname: Vincent
authors.forename: Jacques
authors.initials: J
authors.lastname: Gallay
authors.forename: Manuela
authors.initials: M
authors.lastname: Argentini
authors.forename: David
authors.initials: D
authors.lastname: Cornu
authors.forename: Frédéric
authors.initials: F
authors.lastname: Boccard
authors.forename: Bruno
authors.initials: B
authors.lastname: Lemaître
authors.forename: Herman
authors.initials: H
authors.lastname: van Tilbeurgh
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000235:genetics; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004330:Drosophila / Q000382:microbiology; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism; D009154:Mutation; D016973:Pectobacterium carotovorum / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity; D011485:Protein Binding / Q000235:genetics; D037521:Virulence Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D008563:Membrane Lipids; D037521:Virulence Factors; D003545:Cysteine