Contribution of SPI-4 genes to the virulence of Salmonella enterica
Contribution of SPI-4 genes to the virulence of Salmonella enterica
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DOI：
10.1111/j.1574-6968.2007.00871.x
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发表时间：
2007-10-01
影响因子：
2.1
通讯作者：
Nagy, Gabor
中科院分区：
文献类型：
--
作者：
Kiss, Tuende;Morgan, Eirwen;Nagy, Gabor
沙门氏菌致病岛-4（SPI-4）是一个27 kb的区域，携带六个基因，命名为siiABCDEF。SiiC、SiiD和SiiF形成用于分泌SiiE的I型分泌装置，SiiE是一种有助于牛肠道定殖的巨大（类似于600 kDa）蛋白质。本文显示SPI-4的缺失减弱了小鼠中肠道沙门氏菌血清型鼠伤寒和肠杆菌的口服毒力。在SPI-4丧失后，两种血清型中的50%致死剂量升高。此外，三角洲SPI-4突变体的竞争在系统器官中的野生型菌株在共同挑战模型。SPI-4对S.肠杆菌菌株，这是合理的分泌蛋白SiiE在该菌株中的水平较低相比，S。鼠伤寒。竞争试验表明，这6个基因都是S.鼠伤寒。然而，Δ siiA和Δ siiB突变体能够将SiiE分泌到培养物上清液中。然而，与野生型菌株相比，这两种突变体中分泌的SiiE的量减少。此外，SiiE水平的下调显示在表现出深粗糙表型的结构和调节脂多糖突变体中。
Salmonella pathogenicity island-4 (SPI-4) is a 27-kb region that carries six genes designated siiABCDEF. SiiC, SiiD, and SiiF form a type I secretion apparatus for the secretion of SiiE, a huge (similar to 600 kDa) protein contributing to the colonization of the bovine intestines. Here it is shown that loss of SPI-4 attenuates the oral virulence of Salmonella enterica serovars Typhimurium and Enteritidis in mice. Fifty percent lethal doses were elevated in both serovars upon the loss of SPI-4. Moreover, Delta SPI-4 mutants were outcompeted in systemic organs by their wild-type strains in a cochallenge model. Contribution of SPI-4 to virulence appeared less pronounced in the S. Enteritidis strain, which was justified by lower levels of the secreted protein SiiE in this strain in comparison with S. Typhimurium. Competition assays with isogenic mutants lacking individual genes of the island showed that all six genes were required for full virulence of S. Typhimurium. Delta siiA and Delta siiB mutants were, nevertheless, able to secrete SiiE to culture supernatants. The amount of secreted SiiE was, however, reduced in these two mutants compared with the wild-type strain. Furthermore, a down-regulation of SiiE levels is shown in structural and regulatory lipopolysaccharide mutants exhibiting the deep-rough phenotype.