Schmitt M P, Twiddy E M, Holmes R K
Department of Microbiology, Uniformed Services University of the Health Sciences, Bethesda, MD 20814-4977.
Proc Natl Acad Sci U S A. 1992 Aug 15;89(16):7576-80. doi: 10.1073/pnas.89.16.7576.
The diphtheria toxin repressor gene (dtxR) encodes a protein (DtxR) that regulates transcription of the diphtheria toxin gene (tox) by an iron-dependent mechanism. Cloned dtxR was expressed in Escherichia coli from the phage T7 gene 10 promoter, and DtxR was purified. Specific binding of DtxR to the tox+ operator was dependent on reduction of DtxR and the presence of ferrous ions. DtxR protected a sequence of approximately 30 nucleotide pairs, partially overlapping the tox promoter and containing a region of dyad symmetry, from digestion by DNase I. DtxR exhibited very little binding to the mutant tox-201 operator region and failed to bind to the promoter/operator region of the ferric uptake regulation (fur) gene of E. coli.
白喉毒素阻遏基因（dtxR）编码一种蛋白质（DtxR），该蛋白质通过铁依赖机制调节白喉毒素基因（tox）的转录。克隆的dtxR在噬菌体T7基因10启动子的大肠杆菌中表达，并纯化了DtxR。DtxR与tox +操纵子的特异性结合取决于DtxR的还原和亚铁离子的存在。DtxR保护了一段约30个核苷酸对的序列，该序列与tox启动子部分重叠并包含一个二元对称区域，使其免受DNase I的消化。DtxR与突变的tox-201操纵子区域的结合非常少，并且不能与大肠杆菌铁摄取调节（fur）基因的启动子/操纵子区域结合。
