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Molecular and virulence characteristics of an outer membrane-associated RTX exoprotein in Pasteurella pneumotropica

Hiraku Sasaki1, Hiroki Ishikawa, Toru Sato

  • 1Animal Research Center, Tokyo Medical University, Shinjuku, Tokyo, Japan. h-sasaki@tokyo-med.ac.jp

BMC Microbiology
|March 18, 2011
PubMed
Abstract

Insights

Researchers identified a new RTX toxin, PnxIIIA, in Pasteurella pneumotropica. This toxin aids bacterial adhesion to extracellular matrices and enhances hemagglutination, contributing to its role as a rodent pathogen.

Area of Science:

  • Microbiology
  • Bacterial Pathogenesis
  • Toxinology

Background:

  • Pasteurella pneumotropica is a common bacterium in lab rodents, causing illness in immunocompromised animals.
  • Two RTX toxins (PnxIA, PnxIIA) were previously known in this species.
  • This study focuses on a newly identified RTX toxin, PnxIIIA, and its secretion system.

Purpose of the Study:

  • To identify and characterize a novel RTX toxin, PnxIIIA, in Pasteurella pneumotropica.
  • To analyze the function and localization of PnxIIIA.
  • To understand the role of PnxIIIA in bacterial pathogenesis.

Main Methods:

  • Bioinformatic analysis and identification of the PnxIIIA gene and its secretion system.
  • Expression and purification of recombinant PnxIIIA protein (rPnxIIIA).
  • In vitro assays to assess cytotoxicity, extracellular matrix binding, and hemagglutination.
  • Protein localization studies using P. pneumotropica ATCC 35149.

Main Results:

  • PnxIIIA possesses RTX repeats and unique large repeat sequences, similar to prokaryotic outer membrane proteins.
  • Recombinant PnxIIIA exhibited cytotoxicity towards mouse macrophages, which was partially inhibited by anti-CD11a antibody.
  • PnxIIIA demonstrated binding to extracellular matrices and caused hemagglutination, dependent on its large repeat sequences.
  • PnxIIIA is primarily located in the outer membrane of P. pneumotropica in an oligomeric form and is less cytotoxic than PnxIA and PnxIIA.

Conclusions:

  • PnxIIIA is a cell-surface-associated RTX toxin in P. pneumotropica.
  • PnxIIIA plays a role in bacterial adhesion to extracellular matrices.
  • PnxIIIA contributes to hemagglutination, indicating its involvement in the pathogenicity of this rodent pathogen.

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