School of Biosciences, University of Birmingham, Birmingham, UK.
FEMS Microbiol Lett. 2010 Apr;305(1):28-34. doi: 10.1111/j.1574-6968.2010.01907.x. Epub 2010 Jan 20.
Random mutagenesis has been used to identify the target DNA sites for the MalI repressor at the divergent Escherichia coli K-12 malX-malI promoters. The malX promoter is repressed by MalI binding to a DNA site located from position -24 to position -9, upstream of the malX promoter transcript start. The malI promoter is repressed by MalI binding from position +3 to position +18, downstream of the malI transcript start. MalI binding at the malI promoter target is not required for repression of the malX promoter. Similarly, MalI binding at the malX promoter target is not required for repression of the malI. Although the malX and malI promoters are regulated by a single DNA site for cyclic AMP receptor protein, they function independently and each is repressed by MalI binding to a different independent operator site.
随机诱变已被用于鉴定大肠杆菌 K-12 中 MalI 阻遏物在 divergent malX-malI 启动子上的靶 DNA 位点。MalX 启动子受 MalI 结合位于 MalX 启动子转录起始上游-24 到-9 位的 DNA 位点的抑制。MalI 启动子受 MalI 结合位于 MalI 转录起始下游+3 到+18 位的抑制。MalI 在 malI 启动子靶位的结合对于抑制 MalX 启动子不是必需的。同样，MalI 在 MalX 启动子靶位的结合对于抑制 malI 也不是必需的。尽管 malX 和 malI 启动子受单个 cAMP 受体蛋白 DNA 位点的调控，但它们独立发挥功能，每个启动子都受到 MalI 结合不同独立操纵子位点的抑制。
