Transcription and autoregulation of the Rv3134c-devR-devS operon of Mycobacterium tuberculosis
Transcription and autoregulation of the Rv3134c-devR-devS operon of Mycobacterium tuberculosis
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DOI：
10.1099/mic.0.28333-0
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发表时间：
2005-12-01
期刊：
影响因子：
2.8
通讯作者：
Tyagi, JS
中科院分区：
文献类型：
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作者：
Bagchi, G;Chauhan, S;Tyagi, JS
DevR是一种转录调节因子，介导结核分枝杆菌对氧限制和一氧化氮暴露的遗传反应。devR与编码其同源传感器激酶的devS和上游基因Rv 3134 c一起沿着共转录。该操纵子的转录活性的特点是引物延伸，转录融合和电泳迁移率变动分析（EMSA）在有氧条件下。在Rv 3134 c和devR的上游检测到转录起始点（Tsps），并且主要转录物来源于Rv 3134 c的上游。通过计算机模拟分析，在Tsps附近检测到与σ因子共有元件和与DevR结合基序相似的序列。与启动子区域和DevR蛋白的EMSA显示，DevR以具有不同亲和力的序列特异性方式与其自身的启动子结合。与引物延伸和EMSA数据一致，使用在耻垢分枝杆菌和大肠杆菌中进行的报告基因测定，Rv 3134 c启动子而不是devR启动子被确定为该操纵子的主要启动子。此外，DevR调节devR和Rv 3134 c启动子的活性。从这些发现推断Rv 3134 c-devR-devS操纵子从多个启动子转录并且是自动调节的。
DevR is a transcriptional regulator that mediates the genetic response of Mycobacterium tuberculosis to oxygen limitation and nitric oxide exposure. devR is co-transcribed along with devS, which encodes its cognate sensor kinase, and an upstream gene, Rv3134c. The transcriptional activity of this operon was characterized by primer extension, transcriptional fusion and electrophoretic mobility shift assays (EMSAs) under aerobic conditions. Transcription start points (Tsps) were detected upstream of both Rv3134c and devR, and the major transcript was derived from upstream of Rv3134c. Sequences with similarity to sigma factor consensus elements and to DevR-binding motifs were detected in the vicinity of the Tsps by in silico analysis. EMSAs with promoter regions and DevR protein showed that DevR binds to its own promoters in a sequence-specific manner with differing affinities. Consistent with the primer extension and EMSA data, Rv3134c promoters, and not devR promoters, were determined to be the principal promoters of this operon using reporter assays performed in Mycobacterium smegmatis and Escherichia coli. Furthermore, DevR modulated the activity of both devR and Rv3134c promoters. From these findings it is inferred that the Rv3134c-devR-devS operon is transcribed from multiple promoters and is autoregulated.