Biochemistry Department, College of Science, King Saud University, Riyadh, Saudi Arabia.
FEMS Microbiol Lett. 2013 Jan;338(1):62-7. doi: 10.1111/1574-6968.12027. Epub 2012 Nov 8.
The Escherichia coli melR gene encodes the MelR transcription factor that controls melibiose utilization. Expression of melR is autoregulated by MelR, which represses the melR promoter by binding to a target that overlaps the transcript start. Here, we show that MelR-dependent repression of the melR promoter can be enhanced by the presence of a second single DNA site for MelR located up to 250 base pairs upstream. Parallels with AraC-dependent repression at the araC-araBAD regulatory region and the possibility of the MelR-dependent repression loop formation are discussed. The results show that MelR bound at two distal loci can cooperate together in transcriptional repression.
大肠杆菌 melR 基因编码 MelR 转录因子，该因子控制棉子糖的利用。melR 的表达受 MelR 自身调控，后者通过与重叠转录起始的靶标结合来抑制 melR 启动子。在这里，我们表明，位于上游多达 250 个碱基对的第二个 MelR 单 DNA 位点的存在可以增强 MelR 对 melR 启动子的依赖性抑制。讨论了与 AraC 在 araC-araBAD 调控区的依赖性抑制的相似性，以及 MelR 依赖性抑制环形成的可能性。结果表明，结合在两个远端基因座上的 MelR 可以协同进行转录抑制。
