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首页> 外文期刊>Infection and immunity >Legionella pneumophila Type II Protein Secretion Promotes Virulence in the A/J Mouse Model of Legionnaires' Disease Pneumonia
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Legionella pneumophila Type II Protein Secretion Promotes Virulence in the A/J Mouse Model of Legionnaires' Disease Pneumonia

机译：军团菌肺炎II型蛋白分泌促进退伍军人病肺炎的A / J小鼠模型中的毒力。

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Legionella pneumophila, the gram-negative agent of Legionnaires' disease, possesses type IV pili and a type II protein secretion (Lsp) system, both of which are dependent upon the PilD prepilin peptidase. By analyzing multiple pilD mutants and various types of Lsp mutants as well as performing trans-complementation of these mutants, we have confirmed that PilD and type II secretion genes are required for L. pneumophila infection of both amoebae and human macrophages. Based upon a complete analysis of lspDE, lspF, and lspG mutants, we found that the type II system controls the secretion of protease, RNase, lipase, phospholipase A, phospholipase C, lysophospholipase A, and tartrate-sensitive and tartrate-resistant acid phosphatase activities and influences the appearance of colonies. Examination of the developing L. pneumophila genome database indicated that the organism has two other loci (lspC and lspLM) that are predicted to promote secretion and thus a set of genes that is comparable to the type II secretion genes in other gram-negative bacteria. In contrast to lsp mutants, L. pneumophila pilus mutants lacking either the PilQ secretin, the PspA pseudopilin, or pilin were not defective for colonial growth, secreted activities, or intracellular replication. L. pneumophila dot/icm mutants were also not impaired for type II-dependent exoenzymes. Upon intratracheal inoculation into A/J mice, lspDE, lspF, and pilD mutants, but not pilus mutants, exhibited a reduced ability to grow in the lung, as measured by competition assays. The lspF mutant was also defective in an in vivo kinetic assay. Examination of infected mouse sera revealed that type II secreted proteins are expressed in vivo. Thus, the L. pneumophila Lsp system is a virulence factor and the only type II secretion system linked to intracellular infection.
机译：嗜肺军团杆菌（Legionella pneumophila）是军团病的革兰氏阴性菌，具有IV型菌毛和II型蛋白分泌（Lsp）系统，这两个系统均依赖于PilD prepilin肽酶。通过分析多个 pilD 突变体和各种类型的Lsp突变体，以及对这些突变体进行 trans 互补，我们已经证实PilD和II型分泌基因是< em> L。变形虫感染了变形虫和人类巨噬细胞。根据对 lspDE ， lspF 和 lspG 突变体的完整分析，我们发现II型系统可控制蛋白酶，RNase，脂肪酶，磷脂酶A，磷脂酶C，溶血磷脂酶A以及酒石酸敏感和抗酒石酸的酸性磷酸酶活性并影响菌落的出现。检验正在发展的 L。嗜肺菌基因组数据库表明，该生物还有另外两个基因座（ lspC 和 lspLM ），预计可促进分泌，因此有一组与其他革兰氏阴性细菌中的II型分泌基因。与 lsp 突变体相反， L。缺乏PilQ分泌蛋白，PspA假菌毛蛋白或菌毛蛋白的肺炎菌菌毛突变体对结肠生长，分泌的活性或细胞内复制没有缺陷。 L。肺炎点/ icm 突变体也不受II型依赖型外切酶的损害。在气管内接种A / J小鼠后， lspDE ， lspF 和 pilD 突变体（但不是菌毛突变体）表现出降低的生长能力。通过竞争测定法测量的肺。在体内动力学测定中， lspF 突变体也存在缺陷。检查受感染的小鼠血清后发现，II型分泌蛋白在体内表达。因此， L。肺炎支原体Lsp系统是一种毒力因子，是唯一与细胞内感染相关的II型分泌系统。

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