title: Interaction ofBacteroides fragilisToxin with Outer Membrane Vesicles Reveals New Mechanism of Its Secretion and Delivery.
abstract: The only recognized virulence factor of enterotoxigenicBacteroides fragilis(ETBF) that accompanies bloodstream infections is the zinc-dependent non-lethal metalloproteaseB. fragilistoxin (BFT). The isolated toxin stimulates intestinal secretion, resulting in epithelial damage and necrosis. Numerous publications have focused on the interrelation of BFT with intestinal inflammation and colorectal neoplasia, but nothing is known about the mechanism of its secretion and delivery to host cells. However, recent studies of gram-negative bacteria have shown that outer membrane vesicles (OMVs) could be an essential mechanism for the spread of a large number of virulence factors. Here, we show for the first time that BFT is not a freely secreted protease but is associated with OMVs. Our findings indicate that only outer surface-exposed BFT causes epithelial cell contact disruption. According to ourin silicomodels confirmed by Trp quenching assay and NMR, BFT has special interactions with outer membrane components such as phospholipids and is secreted during vesicle formation. Moreover, the strong cooperation of BFT with polysaccharides is similar to the behavior of lectins. Understanding the molecular mechanisms of BFT secretion provides new perspectives for investigating intestinal inflammation pathogenesis and its prevention.
authors.affiliation: Federal Research and Clinical Centre of Physical-Chemical Medicine Federal Medical Biological Agency Moscow, Russia.
authors.forename: Natalya B
authors.initials: NB
authors.lastname: Zakharzhevskaya
authors.affiliation: Federal Research and Clinical Centre of Physical-Chemical Medicine Federal Medical Biological AgencyMoscow, Russia; Department of Polyelectrolytes and Surface-Active Polymers, Topchiev Institute of Petrochemical SynthesisMoscow, Russia; Department of Molecular Virology, FSBI Research Institute of Influenza, Ministry of Health of the Russian FederationSaint Petersburg, Russia.
authors.forename: Vladimir B
authors.initials: VB
authors.lastname: Tsvetkov
authors.affiliation: Federal Research and Clinical Centre of Physical-Chemical Medicine Federal Medical Biological Agency Moscow, Russia.
authors.forename: Anna A
authors.initials: AA
authors.lastname: Vanyushkina
authors.affiliation: Federal Research and Clinical Centre of Physical-Chemical Medicine Federal Medical Biological Agency Moscow, Russia.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Varizhuk
authors.affiliation: Federal Research and Clinical Centre of Physical-Chemical Medicine Federal Medical Biological Agency Moscow, Russia.
authors.forename: Daria V
authors.initials: DV
authors.lastname: Rakitina
authors.affiliation: Federal Research and Clinical Centre of Physical-Chemical Medicine Federal Medical Biological Agency Moscow, Russia.
authors.forename: Victor V
authors.initials: VV
authors.lastname: Podgorsky
authors.affiliation: Lab of Genome Structural Organization, Institute of Cytology, Russian Academy of SciencesSaint Petersburg, Russia; Institute of Nanobiotechnologies, Peter the Great St. Petersburg Polytechnic UniversitySaint Petersburg, Russia.
authors.forename: Innokentii E
authors.initials: IE
authors.lastname: Vishnyakov
authors.affiliation: Federal Research and Clinical Centre of Physical-Chemical Medicine Federal Medical Biological Agency Moscow, Russia.
authors.forename: Daria D
authors.initials: DD
authors.lastname: Kharlampieva
authors.affiliation: Federal Research and Clinical Centre of Physical-Chemical Medicine Federal Medical Biological Agency Moscow, Russia.
authors.forename: Valentin A
authors.initials: VA
authors.lastname: Manuvera
authors.affiliation: N.F. Gamalei Federal Research Centre for Epidemiology and Microbiology, Ministry of Health Russian Federation Moscow, Russia.
authors.forename: Fedor V
authors.initials: FV
authors.lastname: Lisitsyn
authors.affiliation: N.F. Gamalei Federal Research Centre for Epidemiology and Microbiology, Ministry of Health Russian Federation Moscow, Russia.
authors.forename: Elena A
authors.initials: EA
authors.lastname: Gushina
authors.affiliation: Federal Research and Clinical Centre of Physical-Chemical Medicine Federal Medical Biological AgencyMoscow, Russia; Lab of Systems Biology, Moscow Institute of Physics and TechnologyDolgoprudny, Russia.
authors.forename: Vassili N
authors.initials: VN
authors.lastname: Lazarev
authors.affiliation: Federal Research and Clinical Centre of Physical-Chemical Medicine Federal Medical Biological AgencyMoscow, Russia; Lab of Systems Biology, Moscow Institute of Physics and TechnologyDolgoprudny, Russia; Department of Proteomics, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of SciencesMoscow, Russia.
authors.forename: Vadim M
authors.initials: VM
authors.lastname: Govorun
mesh_terms: D001427:Bacterial Toxins; D001441:Bacteroides fragilis / Q000166:cytology / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000378:metabolism*; D021381:Protein Transport; D022142:Secretory Vesicles / Q000378:metabolism*
chemical_list: D001427:Bacterial Toxins; C405031:Bacteroides fragilis toxin; D008666:Metalloendopeptidases
keywords: Electron microscopy; NMR; fluorescence quenching; lipid protein interactions; shot gun lipidomics; toxin delivery