title: Molecular and virulence characteristics of an outer membrane-associated RTX exoprotein in Pasteurella pneumotropica.
abstract: BACKGROUND
  Pasteurella pneumotropica is a ubiquitous bacterium that is frequently isolated from laboratory rodents and causes various clinical symptoms in immunodeficient animals. Currently two RTX toxins, PnxIA and PnxIIA, which are similar to hemolysin-like high-molecular-weight exoproteins are known in this species. In this study, we identified and analyzed a further RTX toxin named PnxIIIA and the corresponding type I secretion system.
  
  
  RESULTS
  The RTX exoprotein, PnxIIIA, contains only a few copies of the RTX repeat-like sequence and 3 large repeat sequences that are partially similar to the outer membrane protein found in several prokaryotes. Recombinant PnxIIIA protein (rPnxIIIA) was cytotoxic toward J774A.1 mouse macrophage cells, whereas cytotoxicity was attenuated by the addition of anti-CD11a monoclonal antibody. rPnxIIIA could bind to extracellular matrices (ECMs) and cause hemagglutination of sheep erythrocytes. Binding was dependent on the 3 large repeat sequences in PnxIIIA. Protein interaction analyses indicated that PnxIIIA is mainly localized in the outer membrane of P. pneumotropica ATCC 35149 in a self-assembled oligomeric form. PnxIIIA is less cytotoxic to J774A.1 cells than PnxIA and PnxIIA.
  
  
  CONCLUSIONS
  The results implicate that PnxIIIA is located on the cell surface and participates in adhesion to ECMs and enhanced hemagglutination in the rodent pathogen P. pneumotropica.
authors.affiliation: Animal Research Center, Tokyo Medical University, Shinjuku, Tokyo, Japan. h-sasaki@tokyo-med.ac.jp
authors.forename: Hiraku
authors.initials: H
authors.lastname: Sasaki
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ishikawa
authors.forename: Toru
authors.initials: T
authors.lastname: Sato
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sekiguchi
authors.forename: Hiromi
authors.initials: H
authors.lastname: Amao
authors.forename: Eiichi
authors.initials: E
authors.lastname: Kawamoto
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Shirama
mesh_terms: D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism / Q000633:toxicity; D001427:Bacterial Toxins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism / Q000633:toxicity*; D002460:Cell Line; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004912:Erythrocytes / Q000187:drug effects; D006384:Hemagglutination; D008264:Macrophages / Q000187:drug effects; D051379:Mice; D008969:Molecular Sequence Data; D044142:Pasteurella pneumotropica / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity*; D021381:Protein Transport; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000633:toxicity; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D012756:Sheep; D014774:Virulence
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001427:Bacterial Toxins; D004269:DNA, Bacterial; D011994:Recombinant Proteins