Pérez-Martín J, Timmis K N, de Lorenzo V
Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
J Biol Chem. 1994 Sep 9;269(36):22657-62.
The role of integration host factor (IHF) in the regulation of the sigma 54-dependent promoter Pu of the TOL plasmid of Pseudomonas putida has been examined. We have selected in vivo insertions of intrinsically curved DNA that restore the responsiveness of an IHF-binding site deletion variant of Pu to the cognate activator of the system, XylR. We found five Pu derivatives which had inserted a core sequence with 6 phased [A]6 tracts, flanked by different lengths of DNA at the location of the former IHF site. They displayed 40-100% of the activity of Pu, were independent of IHF, and maintained the overall geometry of the wild-type promoter. The induction patterns of Pu, compared to those of hybrid promoters, were virtually indistinguishable. This supports the notion that, in native conditions, IHF co-regulates the system by providing a structural aid for promoter architecture and not by interacting directly with the RNA polymerase, as it has been suggested with other known IHF-dependent promoters.
已对整合宿主因子（IHF）在恶臭假单胞菌TOL质粒的σ⁵⁴依赖型启动子Pu调控中的作用进行了研究。我们在体内选择了固有弯曲DNA的插入片段，这些片段可恢复Pu的IHF结合位点缺失变体对该系统同源激活因子XylR的响应性。我们发现了五个Pu衍生物，它们在前IHF位点的位置插入了一个核心序列，该核心序列有6个相位[ A ]₆序列，两侧是不同长度的DNA。它们表现出Pu活性的40 - 100%，不依赖于IHF，并保持了野生型启动子的整体几何形状。与杂合启动子相比，Pu的诱导模式几乎无法区分。这支持了这样一种观点，即在天然条件下，IHF通过为启动子结构提供结构辅助来共同调节该系统，而不是像其他已知的依赖IHF的启动子那样直接与RNA聚合酶相互作用。
