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

• Published in: BMC microbiology Vol. 11; no. 1; p. 55
• Main Authors: Sasaki, Hiraku, Ishikawa, Hiroki, Sato, Toru, Sekiguchi, Satoshi, Amao, Hiromi, Kawamoto, Eiichi, Matsumoto, Tetsuya, Shirama, Kazuhiko
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 17.03.2011; BioMed Central; BMC
• Subjects: Animals; Bacteria; Bacterial Outer Membrane Proteins - genetics; Bacterial Outer Membrane Proteins - isolation & purification; Bacterial Outer Membrane Proteins - metabolism; Bacterial Outer Membrane Proteins - toxicity; Bacterial Toxins - genetics; Bacterial Toxins - isolation & purification; Bacterial Toxins - metabolism; Bacterial Toxins - toxicity; Causes of; Cell Line; DNA, Bacterial - chemistry; DNA, Bacterial - genetics; Erythrocytes - drug effects; Genes; Gram-negative bacteria; Health aspects; Hemagglutination; Immunological deficiency syndromes; Macrophages - drug effects; Mice; Microbiology; Molecular Sequence Data; Monoclonal antibodies; Pasteurella pneumotropica - genetics; Pasteurella pneumotropica - metabolism; Pasteurella pneumotropica - pathogenicity; Physiological aspects; Protein Transport; Proteins; Recombinant Proteins - genetics; Recombinant Proteins - isolation & purification; Recombinant Proteins - toxicity; Risk factors; Rodents; Sequence Alignment; Sequence Analysis, DNA; Sheep; Virulence; Japan
• ISSN: 1471-2180; 1471-2180
• DOI: 10.1186/1471-2180-11-55

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. 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. 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.