vgrG is separately transcribed from hcp in T6SS orphan clusters and is under the regulation of IHF and HapR.
vgrG is separately transcribed from hcp in T6SS orphan clusters and is under the regulation of IHF and HapR.
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DOI：
10.1016/j.bbrc.2021.04.092
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发表时间：
2021-04
影响因子：
3.1
通讯作者：
Anran Zhang;Yu Han;Yuanming Huang;Xiao Hu;Ping Liu;Xiaoshu Liu;B. Kan;W. Liang
中科院分区：
文献类型：
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作者：
Anran Zhang;Yu Han;Yuanming Huang;Xiao Hu;Ping Liu;Xiaoshu Liu;B. Kan;W. Liang
霍乱弧菌（V. cholesterol）和河流弧菌（V. fluvialis）具有高度同源的T6 SS，T6 SS由一个大簇和两个小的孤簇或辅助簇组成，每个簇通常被认为是一个操纵子。在这里，我们发现每个小簇中的基因被组织成两个转录单位。具体来说，内管编码基因hcp/tssD高度转录为一个单顺反子，而末端成分vgrG/tssI及其下游效应基因和免疫基因则位于一个转录水平极低的多顺反子中。这一结论得到了mRNA丰度的qPCR分析、报告基因融合分析和RT-PCR分析的转录单位定义的支持。以河流弧菌tssI 2_a0为例，我们进一步证明了群体感应（quorum sensing，QS）调节因子HapR和全局调节因子IHF通过直接结合其启动子区来激活vgrG/tssI的转录。这些研究加深了我们对T6 SS系统的理解，突出了其在功能执行过程中调控的复杂性。
V. cholerae, the causative agent of cholera epidemic, andV. fluvialis, the emerging foodborne pathogen, share highly homologous T6SS consisting of one large cluster and two small orphan or auxiliary clusters, and each of which was generally recognized as one operon. Here, we showed that the genes in each of the small clusters are organized into two transcriptional units. Specifically, the inner tube coding genehcp/tssDis highly transcribed as one monocistron, while the tip componentvgrG/tssIand its downstream effector and immunity genes are in one polycistron with very low transcriptional level. This conclusion is supported by qPCR analysis of mRNA abundance, reporter fusion analysis and transcriptional unit definition with RT-PCR analysis. TakingtssI2_aofV. fluvialisas an example, we further demonstrated that quorum sensing (QS) regulator HapR and global regulator IHF activatevgrG/tssItranscription by directly binding to its promoter region. Taken together, current studies deepen our understanding of T6SS system, highlighting its regulatory complexity during functional execution process.