title: Enterohaemorrhagic Escherichia coli haemolysin is cleaved and inactivated by serine protease EspPα.
abstract: The haemolysin from enterohaemorrhagic Escherichia coli (EHEC-Hly) and the serine protease EspPα are putative virulence factors of EHEC. We investigated the interplay between these secreted factors and demonstrate that EspPα cleaves the 107 kDa large EHEC-Hly. Degradation was observed when purified EspPα was added to a growing culture of an EHEC-Hly-expressing strain, with isolated proteins and with coexpressing strains, and was independent of the EHEC serotype. EHEC-Hly breakdown occurred as a multistage process with the formation of characteristic fragments with relative molecular masses of ~82 kDa and/or ~84 kDa and ~34 kDa. The initial cleavage occurred in the N-terminal hydrophobic domain of EHEC-Hly between Leu(235) and Ser(236) and abolished its haemolytic activity. In a cellular infection system, the cytolytic potential of EHEC-Hly-secreting recombinant strains was abolished when EspPα was coexpressed. EHEC in contact with human intestinal epithelial cells simultaneously upregulated their EHEC-Hly and EspP indicating that both molecules might interact under physiological conditions. We propose the concept of bacterial effector molecule interference (BEMI), reflecting the concerted interplay of virulence factors. Interference between effector molecules might be an additional way to regulate virulence functions and increases the complexity of monomolecular phenotypes.
authors.affiliation: Institute of Food Chemistry, University of Münster, Corrensstrasse 45, Münster, Germany. jbrockm@uni-muenster.de
authors.forename: Jens
authors.initials: J
authors.lastname: Brockmeyer
authors.forename: Thomas
authors.initials: T
authors.lastname: Aldick
authors.forename: Jens
authors.initials: J
authors.lastname: Soltwisch
authors.forename: Wenlan
authors.initials: W
authors.lastname: Zhang
authors.forename: Philip I
authors.initials: PI
authors.lastname: Tarr
authors.forename: André
authors.initials: A
authors.lastname: Weiss
authors.forename: Klaus
authors.initials: K
authors.lastname: Dreisewerd
authors.forename: Johannes
authors.initials: J
authors.lastname: Müthing
authors.forename: Martina
authors.initials: M
authors.lastname: Bielaszewska
authors.forename: Helge
authors.initials: H
authors.lastname: Karch
mesh_terms: D002478:Cells, Cultured; D054324:Enterohemorrhagic Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D004847:Epithelial Cells / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006460:Hemolysin Proteins / Q000378:metabolism*; D006461:Hemolysis; D006801:Humans; D012329:RNA, Bacterial / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D029968:Escherichia coli Proteins; D006460:Hemolysin Proteins; D012329:RNA, Bacterial; D011994:Recombinant Proteins; D037521:Virulence Factors; C107189:EspP protein, E coli; D012697:Serine Endopeptidases