title: Type three secretion system-mediated escape of Burkholderia pseudomallei into the host cytosol is critical for the activation of NFκB.
abstract: BACKGROUND
  Burkholderia pseudomallei is the causative agent of melioidosis, a potentially fatal disease endemic in Southeast Asia and Northern Australia. This Gram-negative pathogen possesses numerous virulence factors including three "injection type" type three secretion systems (T3SSs). B. pseudomallei has been shown to activate NFκB in HEK293T cells in a Toll-like receptor and MyD88 independent manner that requires T3SS gene cluster 3 (T3SS3 or T3SSBsa). However, the mechanism of how T3SS3 contributes to NFκB activation is unknown.
  
  
  RESULTS
  Known T3SS3 effectors are not responsible for NFκB activation. Furthermore, T3SS3-null mutants are able to activate NFκB almost to the same extent as wildtype bacteria at late time points of infection, corresponding to delayed escape into the cytosol. NFκB activation also occurs when bacteria are delivered directly into the cytosol by photothermal nanoblade injection.
  
  
  CONCLUSIONS
  T3SS3 does not directly activate NFκB but facilitates bacterial escape into the cytosol where the host is able to sense the presence of the pathogen through cytosolic sensors leading to NFκB activation.
authors.forename: Boon Eng
authors.initials: BE
authors.lastname: Teh
authors.forename: Christopher Todd
authors.initials: CT
authors.lastname: French
authors.forename: Yahua
authors.initials: Y
authors.lastname: Chen
authors.forename: Isabelle Gek Joo
authors.initials: IG
authors.lastname: Chen
authors.forename: Ting-Hsiang
authors.initials: TH
authors.lastname: Wu
authors.forename: Enrico
authors.initials: E
authors.lastname: Sagullo
authors.forename: Pei-Yu
authors.initials: PY
authors.lastname: Chiou
authors.forename: Michael A
authors.initials: MA
authors.lastname: Teitell
authors.forename: Jeff F
authors.initials: JF
authors.lastname: Miller
authors.affiliation: Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore. yunn_hwen_gan@nuhs.edu.sg.
authors.forename: Yunn-Hwen
authors.initials: YH
authors.lastname: Gan
mesh_terms: D058947:Bacterial Secretion Systems; D016957:Burkholderia pseudomallei / Q000276:immunology* / Q000502:physiology*; D002460:Cell Line; D003600:Cytosol / Q000382:microbiology*; D004847:Epithelial Cells / Q000382:microbiology*; D006801:Humans; D016328:NF-kappa B / Q000378:metabolism*; D037521:Virulence Factors / Q000378:metabolism*
chemical_list: D058947:Bacterial Secretion Systems; D016328:NF-kappa B; D037521:Virulence Factors