Molecular and virulence characteristics of an outer membrane-associated RTX exoprotein in Pasteurella pneumotropica
Molecular and virulence characteristics of an outer membrane-associated RTX exoprotein in Pasteurella pneumotropica
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DOI：
10.1186/1471-2180-11-55
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发表时间：
2011-03-17
期刊：
影响因子：
4.2
通讯作者：
Shirama, Kazuhiko
中科院分区：
文献类型：
--
作者：
Sasaki, Hiraku;Ishikawa, Hiroki;Shirama, Kazuhiko
背景：嗜肺巴氏杆菌是一种普遍存在的细菌，常从实验啮齿动物中分离出来，可引起免疫缺陷动物的各种临床症状。目前在该物种中已知两种RTX毒素PnxIA和PnxIIA，它们类似于溶血素样高分子外源蛋白。结果：RTX外源蛋白PnxIIIA含有少量的类RTX重复序列和3个大重复序列，与几种原核生物中发现的外膜蛋白部分相似。重组PnxIIIA蛋白(RPnxIIIA)对J774A.1小鼠巨噬细胞具有细胞毒作用，加入抗CD11a单抗后细胞毒作用减弱。RPnxIIIA能与细胞外基质结合，引起绵羊红细胞血凝。结合依赖于PnxIIIA中的3个大重复序列。蛋白质相互作用分析表明，PnxIIIA主要以自组装的寡聚体形式定位在嗜肺假单胞菌ATCC 35149的外膜上。PnxIIIA对J774A.1细胞的杀伤作用弱于PnxIA和PnxIIA。结论：PnxIIIA定位于细胞表面，参与了与ECM的黏附和对啮齿动物嗜肺假单胞菌血凝的增强。
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.