The VirSR Two-Component Signal Transduction System Regulates NetB Toxin Production in Clostridium perfringens
The VirSR Two-Component Signal Transduction System Regulates NetB Toxin Production in Clostridium perfringens
复制标题
DOI：
10.1128/iai.00123-10
复制
发表时间：
2010-07-01
影响因子：
3.1
通讯作者：
Rood, Julian I.
中科院分区：
文献类型：
--
作者：
Cheung, Jackie K.;Keyburn, Anthony L.;Rood, Julian I.
产气荚膜梭菌在家畜中引起几种疾病，包括鸡的坏死性肠炎，由于其健康影响和相关的经济成本，这是家禽业所关注的。新的成孔毒素NetB是该疾病发病机制中的关键毒力因子。在这项研究中，我们研究了NetB毒素产生的调节。In C.在产气荚膜杆菌中，群体感应依赖性VirSR双组分信号转导系统调节编码几种毒素和胞外酶的基因。对netB基因上游序列的分析揭示了潜在的DNA结合位点或VirR盒的存在，这些位点被VirR反应调节因子识别。体外结合实验表明，纯化的VirR能够识别并结合到这些netB相关的VirR盒。此外，使用报告基因测定，netB VirR盒显示出功能性。对两株禽C.产气荚膜杆菌菌株显示出显著减少NetB毒素的产生;来源于这些菌株的培养物上清液对来航雄性肝癌细胞不再具有细胞毒性。与virRS操纵子互补使毒素表型恢复为野生型。结果还表明，VirSR双组分系统在转录水平上调节netB的表达。我们推测，在感染禽的胃肠道中，当C.产气荚膜杆菌细胞达到导致VirSR系统激活的阈值水平。
Clostridium perfringens causes several diseases in domestic livestock, including necrotic enteritis in chickens, which is of concern to the poultry industry due to its health implications and associated economic cost. The novel pore-forming toxin NetB is a critical virulence factor in the pathogenesis of this disease. In this study, we have examined the regulation of NetB toxin production. In C. perfringens, the quorum sensing-dependent VirSR two-component signal transduction system regulates genes encoding several toxins and extracellular enzymes. Analysis of the sequence upstream of the netB gene revealed the presence of potential DNA binding sites, or VirR boxes, that are recognized by the VirR response regulator. In vitro binding experiments showed that purified VirR was able to recognize and bind to these netB-associated VirR boxes. Furthermore, using a reporter gene assay, the netB VirR boxes were shown to be functional. Mutation of the virR gene in two avian C. perfringens strains was shown to significantly reduce the production of the NetB toxin; culture supernatants derived from these strains were no longer cytotoxic to Leghorn male hepatoma cells. Complementation with the virRS operon restored the toxin phenotypes to wild type. The results also showed that the VirSR two-component system regulates the expression of netB at the level of transcription. We postulate that in the gastrointestinal tract of infected birds, NetB production is upregulated when the population of C. perfringens cells reaches a threshold level that leads to activation of the VirSR system.