Induction of type III secretion in Shigella flexneri is associated with differential control of transcription of genes encoding secreted proteins
Induction of type III secretion in Shigella flexneri is associated with differential control of transcription of genes encoding secreted proteins
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DOI：
10.1093/emboj/17.10.2894
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发表时间：
1998-05-15
期刊：
影响因子：
11.4
通讯作者：
Parsot, C
中科院分区：
文献类型：
--
作者：
Demers, B;Sansonetti, PJ;Parsot, C
志贺氏菌是人类细菌性痢疾的病原体，它侵入结肠上皮，引起强烈的炎症反应。志贺氏菌进入上皮细胞涉及由mxi和spa操纵子编码的III型分泌机制以及IpaA-D分泌蛋白。在这项研究中，我们已经确定了46和60 kDa的分泌蛋白的virA和ipaH9.8，分别作为产品，后者是ipaH多基因家族的成员。灭活病毒A不影响进入上皮细胞。使用lacZ转录融合，我们发现，virA和四个ipaH基因的转录，但不是ipaBCDA和mxi操纵子的转录，在生长过程中，在刚果红和iPad突变体的存在下，显着增加，这两种条件下，通过Mxi-Spa机制的分泌增强。virA和ipaH基因的转录在进入上皮细胞后也被瞬时激活。这些结果表明，virA和ipaH基因的转录是由III型分泌机制和调节级联差异控制的基因编码分泌蛋白，其中一些，如virA，是不需要进入的转录。
Shigella, the etiological agent of human bacillary dysentery, invades the colonic epithelium where it induces an intense inflammatory response. Entry of Shigella into epithelial cells involves a type III secretion machinery, encoded by the mxi and spa operons, and the IpaA-D secreted proteins. In this study, we have identified secreted proteins of 46 and 60 kDa as the products of virA and ipaH9.8, respectively, the latter being a member of the ipaH multigene family. Inactivation of virA did not affect entry into epithelial cells. Using lacZ transcriptional fusions, we found that transcription of virA and four ipaH genes, but not that of the ipaBCDA and mxi operons, was markedly increased during growth in the presence of Congo red and in an ipaD mutant, two conditions in which secretion through the Mxi-Spa machinery is enhanced. Transcription of the virA and ipaH genes was also transiently activated upon entry into epithelial cells. These results suggest that transcription of the virA and ipaH genes is regulated by the type III secretion machinery and that a regulatory cascade differentially controls transcription of genes encoding secreted proteins, some of which, like virA, are not required for entry.