Tsui P, Freundlich M
Department of Biochemistry, State University of New York, Stony Brook 11794-5215.
J Mol Biol. 1988 Oct 5;203(3):817-20. doi: 10.1016/0022-2836(88)90212-4.
Integration host factor (IHF) of Escherichia coli is a histone-like protein that is involved both in site-specific recombination and in regulating the expression of a number of phage and bacterial genes. We have shown previously that transcription of the ilvGMEDA operon in E. coli is greatly reduced in IHF mutants. We report here that IHF specifically protects two sites within the ilvGMEDA promoter-regulatory region against DNase I digestion. These sites are located upstream from the promoter and in the leader region just prior to the sequence that specifies the attenuator. The footprinting experiments and gel retardation assays show that these sites have strong affinity for IHF. These data and results with ilvGMEDA-lac promoter fusions suggest a direct role for IHF in expression of the ilvGMEDA operon.
大肠杆菌的整合宿主因子（IHF）是一种类组蛋白，它参与位点特异性重组以及调控许多噬菌体和细菌基因的表达。我们之前已经表明，在IHF突变体中，大肠杆菌ilvGMEDA操纵子的转录大幅减少。我们在此报告，IHF能特异性保护ilvGMEDA启动子调控区域内的两个位点免受DNase I消化。这些位点位于启动子上游以及紧接指定衰减子序列之前的前导区域。足迹实验和凝胶阻滞分析表明，这些位点对IHF具有很强的亲和力。这些数据以及ilvGMEDA - lac启动子融合实验的结果表明，IHF在ilvGMEDA操纵子的表达中起直接作用。
