title: Polarisation of type III translocation by Pseudomonas aeruginosa requires PcrG, PcrV and PopN.
abstract: Type III secretion (TTS) mediated translocation of exoenzymes is a key virulence strategy utilised by the opportunistic pathogen Pseudomonas aeruginosa to deliver exoenzyme effectors into the eukaryotic cell. We have previously shown that type III mediated translocation is a contact dependent process, which requires the secreted translocator proteins PcrV, PopB and PopD. To further analyse this mechanism, HeLa cells were infected with the wild-type strain PAK as well as isogenic pcrV, popB, popD, pcrG and popN mutants. In the presence of eukaryotic cells, expression of exoenzyme S (ExoS) increased. When cells were infected with the wild-type strain PAK no ExoS was detected in the tissue culture medium. This confirms that ExoS translocation by P. aeruginosa occurs by a polarised mechanism. In contrast, high levels of ExoS were recovered in the tissue culture medium when cells were infected with pcrG, pcrV and popN mutants. Additionally, ExoS expression levels were higher for these mutants regardless of inducing conditions. This suggests that PcrG, PcrV and PopN are involved in negative regulation of ExoS expression and secretion, and are required to ensure polarised delivery of effectors into target cells.
authors.affiliation: Department of Medical Countermeasures, FOI NBC-Defence, SE-90182 Umeå, Sweden.
authors.forename: Charlotta
authors.initials: C
authors.lastname: Sundin
authors.forename: Johanna
authors.initials: J
authors.lastname: Thelaus
authors.forename: Jeanette E
authors.initials: JE
authors.lastname: Bröms
authors.forename: Ake
authors.initials: A
authors.lastname: Forsberg
mesh_terms: D036002:ADP Ribose Transferases / Q000235:genetics / Q000378:metabolism*; D000942:Antigens, Bacterial / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D016764:Cell Polarity; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D006367:HeLa Cells / Q000382:microbiology; D006801:Humans; D052899:Pore Forming Cytotoxic Proteins; D011550:Pseudomonas aeruginosa / Q000378:metabolism / Q000472:pathogenicity*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D052899:Pore Forming Cytotoxic Proteins; C118546:antigen V, Pseudomonas; D036002:ADP Ribose Transferases; C444820:exoenzyme S