Torl, a response regulator inhibitor of phage origin in Escherichia coli
Torl, a response regulator inhibitor of phage origin in Escherichia coli
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DOI：
10.1073/pnas.0401927101
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发表时间：
2004-06-22
影响因子：
11.1
通讯作者：
Méjean, V
中科院分区：
文献类型：
--
作者：
Ansaldi, M;Théraulaz, L;Méjean, V
通过使用遗传多拷贝方法，已鉴定出 torI 基因作为 torCAD 操纵子的负调节因子，该操纵子编码大肠杆菌呼吸系统中的三甲胺 N-氧化物还原酶。负面影响是由于先前未识别的噬菌体来源的小 ORF（66 个氨基酸）造成的，我们将其称为 Tor 抑制的 torI。 torI 的过度表达导致 torCAD 操纵子转录减少 8 倍。在三甲胺 N-氧化物存在的情况下，该操纵子受到涉及 TorS 传感器和 TorR 响应调节器的四步磷继电器的正调节。上位实验表明，TorI 在 TorS 下游发挥作用，并且需要 TorR 的存在。体外实验表明，它既不是 TorR 磷酸酶也不是组氨酸激酶抑制剂，并且它与 TorR 的效应结构域结合。出乎意料的是，TorI 并没有阻碍 TorR DNA 结合，我们认为它可能会阻止 RNA 聚合酶招募到 torC 启动子。因此，这项研究揭示了一类以前未表征的反应调节抑制剂。
The torI gene has been identified by using a genetic multicopy approach as a negative regulator of the torCAD operon that encodes the trimethylamine N-oxide reductase respiratory system in Escherichia coli. The negative effect was due to a previously unidentified small ORF (66 aa) of phage origin that we called torI for Tor inhibition. Overexpression of torI led to an 8-fold decrease of the torCAD operon transcription. This operon is positively regulated, in the presence of trimethylamine N-oxide, by a four-step phosphorelay involving the TorS sensor and the TorR response regulator. Epistatic experiments showed that TorI acts downstream of TorS and needs the presence of TorR. In vitro experiments showed that it is neither a TorR phosphatase nor a histidine kinase inhibitor and that it binds to the effector domain of TorR. Unexpectedly, TorI did not impede TorR DNA binding, and we propose that it may prevent RNA polymerase recruitment to the torC promoter. This study thus reveals a previously uncharacterized class of response regulator inhibitors.