title: Type IV pili are not specifically required for contact dependent translocation of exoenzymes by Pseudomonas aeruginosa.
abstract: The type III secretion system (TTSS) of the opportunistic pathogen Pseudomonas aeruginosa enables the bacterium to deliver exoenzymes directly into the eukaryotic cell. In this study we have investigated the role of key factors involved in this process. We could demonstrate that the translocators PopB, PopD and PcrV are absolutely required for delivery of Exoenzyme S into host cells. By analyzing different Tfp (type IV pili) mutants we could establish a correlation between the frequency of bacteria binding to the host cell and the levels of translocated ExoS, thereby verifying that the process is contact dependent. However, there was no absolute requirement for the Tfp per se, since the pilus could be substituted with a different type of adhesin, the non-fimbrial adhesin pH6 antigen of Yersinia pestis. Taken together, our results demonstrate that binding to establish close contact between the type III secretion organelle and the host cell is essential for translocation, while the additional activities of Tfp are not essential for the delivery of TTSS proteins.
authors.affiliation: Department of Medical Countermeasures, FOI NBC-Defence, S-901 82, Umeå, Sweden.
authors.forename: Charlotta
authors.initials: C
authors.lastname: Sundin
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Wolfgang
authors.forename: Stephen
authors.initials: S
authors.lastname: Lory
authors.forename: Ake
authors.initials: A
authors.lastname: Forsberg
authors.forename: Elisabet
authors.initials: E
authors.lastname: Frithz-Lindsten
mesh_terms: D036002:ADP Ribose Transferases / Q000378:metabolism*; D000942:Antigens, Bacterial / Q000378:metabolism; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001427:Bacterial Toxins / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells / Q000382:microbiology; D006801:Humans; D009154:Mutation; D052899:Pore Forming Cytotoxic Proteins; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D001427:Bacterial Toxins; C412007:PopB protein, Ralstonia solanacearum; D052899:Pore Forming Cytotoxic Proteins; C118546:antigen V, Pseudomonas; D036002:ADP Ribose Transferases; C444820:exoenzyme S