Clostridial VirR/VirS regulon involves a regulatory RNA molecule for expression of toxins
Clostridial VirR/VirS regulon involves a regulatory RNA molecule for expression of toxins
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DOI：
10.1046/j.1365-2958.2002.02743.x
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发表时间：
2002-01-01
影响因子：
3.6
通讯作者：
Hayashi, H
中科院分区：
文献类型：
--
作者：
Shimizu, T;Yaguchi, H;Hayashi, H
我们分析了编码 VR-RNA 的区域（bar 下的 (V) irR-(r) bar 下的调控 (RNA) 下），据报道，该区域受到产气荚膜梭菌中双组分 VirR/Virs 系统的正向调节。通过引物延伸分析鉴定的 VR-RNA 启动子前面有一个可能的 VirR 结合位点 (CCAGT TNNNCAC)，它类似于 theta-毒素 (pfoA) 基因启动子区域中存在的重复序列基序。通过同源重组构建的 VR-RNA 无效突变体表现出 α-(pic) 和 kappa-毒素 (colA) 基因转录量的减少，但通过完整 VR-RNA 的互补得以恢复，表明 VR-RNA 区域在产气荚膜梭菌中 pic 和 colA 基因的调节中发挥着重要作用。结果发现，即使删除VR-RNA上编码的hyp7基因或在hyp7编码区引入无义突变，也能观察到调节作用。我们发现 VR-RNA 的小 3' 部分足以激活毒素基因，这表明 VR-RNA 本身可以作为 pic 和 colA 基因的 RNA 调节分子，介导产气荚膜梭菌中 VirR/VirS 系统的调节信息。
We analysed the region encoding VR-RNA ((V) under bar irR-(r) under bar egulated (RNA) under bar), which has been reported to be positively regulated by the two-component VirR/Virs system in Clostridium perfringens. The VR-RNA promoter identified by primer extension analysis was preceded by a probable VirR-binding site (CCAGT TNNNCAC), which resembled a repeated sequence motif present in the promoter region of the theta-toxin (pfoA) gene. A VR-RNA-null mutant, constructed by a homologous recombination, exhibited a reduced amount of transcription of the alpha-(pic) and kappa-toxin (colA) genes, which was restored by the complementation of intact VR-RNA, indicating that the VR-RNA region plays an important role in the regulation of the pic and colA genes in C. perfringens. It was found that the regulatory effect was observed even when the hyp7 gene encoded on VR-RNA was deleted or a nonsense mutation was introduced in the hyp7-coding region. We found that the small 3'-portion of VR-RNA was sufficient for the activation of toxin genes, which suggested that VR-RNA itself could act as an RNA regulatory molecule for the pic and colA genes mediating the regulatory information from the VirR/VirS system in C. perfringens.