title: Outer membrane vesicle-mediated release of cytolethal distending toxin (CDT) from Campylobacter jejuni.
abstract: BACKGROUND
  Background: Cytolethal distending toxin (CDT) is one of the well-characterized virulence factors of Campylobacter jejuni, but it is unknown how CDT becomes surface-exposed or is released from the bacterium to the surrounding environment.
  
  
  RESULTS
  Our data suggest that CDT is secreted to the bacterial culture supernatant via outer membrane vesicles (OMVs) released from the bacteria. All three subunits (the CdtA, CdtB, and CdtC proteins) were detected by immunogold labeling and electron microscopy of OMVs. Subcellular fractionation of the bacteria indicated that, apart from the majority of CDT detected in the cytoplasmic compartment, appreciable amounts (20-50%) of the cellular pool of CDT proteins were present in the periplasmic compartment. In the bacterial culture supernatant, we found that a majority of the extracellular CDT was tightly associated with the OMVs. Isolated OMVs could exert the cell distending effects typical of CDT on a human intestinal cell line, indicating that CDT is present there in a biologically active form.
  
  
  CONCLUSIONS
  Our results strongly suggest that the release of outer membrane vesicles is functioning as a route of C. jejuni to deliver all the subunits of CDT toxin (CdtA, CdtB, and CdtC) to the surrounding environment, including infected host tissue.
authors.affiliation: Department of Molecular Biology, Umeå University, S-90187 Umeå, Sweden. barbro.lindmark@molbiol.umu.se
authors.forename: Barbro
authors.initials: B
authors.lastname: Lindmark
authors.forename: Pramod Kumar
authors.initials: PK
authors.lastname: Rompikuntal
authors.forename: Karolis
authors.initials: K
authors.lastname: Vaitkevicius
authors.forename: Tianyan
authors.initials: T
authors.lastname: Song
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Mizunoe
authors.forename: Bernt Eric
authors.initials: BE
authors.lastname: Uhlin
authors.forename: Patricia
authors.initials: P
authors.lastname: Guerry
authors.forename: Sun Nyunt
authors.initials: SN
authors.lastname: Wai
mesh_terms: D001427:Bacterial Toxins / Q000378:metabolism*; D016123:Campylobacter jejuni / Q000378:metabolism*; D045744:Cell Line, Tumor; D006801:Humans; D018625:Microscopy, Atomic Force; D016253:Microscopy, Immunoelectron; D022161:Transport Vesicles / Q000378:metabolism* / Q000382:microbiology
chemical_list: D001427:Bacterial Toxins; C067044:cytolethal distending toxin