Structural Studies of Two LysR-type Regulators: BenM and CatM

BenM和CatM是LysR型转录调节因子（LTTR），其参与土壤细菌不动杆菌属菌株ADP 1对芳香族化合物降解的复杂调节。虽然LTTR包含细菌转录调节因子的最大家族，但由于过去在表征原子水平蛋白质结构方面的问题，对其功能的清楚理解受到阻碍。BenM和CatM的这些研究将使用蛋白质X射线晶体学来检查转录激活背后的结构变化。将表征响应于效应物结合而发生的构象变化。此外，蛋白质/DNA共结晶方法将解决通过蛋白质-DNA相互作用的改变传递调节信号的结构基础，并评估使两种不同的效应物苯甲酸盐和粘康酸盐对BenM的转录激活具有协同作用的蛋白质构象的变化。这种类型的双诱导物协同作用是一种新型的转录调控形式，可能代表了转录控制的一个重要且广泛的特征。CatM与BenM具有重叠的调控功能，仅对作为效应子的粘康酸起反应，因此提供了用于鉴定转录协同作用所需的关键结构特征的比较模型。BenM和CatM作为复杂的转录调控和LTTR控制的基因表达的范例。变体蛋白质和突变的启动子区DNA也将在结构上表征。以前提出的监管模式将通过这些结构研究进行测试。这些受管制的芳香族化合物降解的研究，除了扩大我们对细菌转录调控的理解，应该增加人造污染物的生物修复的成功，并创造新的生物技术应用。

BenM and CatM are LysR-type transcriptional regulators (LTTR) that participate in the complex regulation of aromatic compound degradation by the soil bacterium Acinetobacter sp. Strain ADP1. While LTTRs comprise the largest family of bacterial transcriptional regulators, a clear understanding of their function has been hampered by past problems in characterizing atomic- level protein structures. These studies of BenM and CatM will use protein X-ray crystallography to examine structural changes underlying transcriptional activation. The conformational changes that occur in response to effector binding will be characterized. Furthermore, protein/DNA co- crystallization methods will address the structural basis for transmitting regulatory signals via alterations in protein-DNA interactions and evaluate the changes in protein conformations that enable two distinct effectors, benzoate and muconate, to have a synergistic effect on transcriptional activation by BenM. This type of dual-inducer synergy is a novel form of transcriptional regulation that may represent an important, and widespread, feature of transcriptional control. CatM, which has overlapping regulatory functions with BenM, responds only to muconate as an effector and thus provides a comparative model for identifying key structural features required for transcriptional synergism. BenM and CatM serve as a paradigm for complex transcriptional regulation and LTTR-controlled gene expression. Variant proteins and mutated promoter region DNA will also be characterized structurally. Previously proposed regulatory models will be tested by these structural studies. These studies of regulated aromatic compound degradation, in addition to expanding our understanding of bacterial transcriptional regulation, should increase the success of bioremediation of man-made pollutants and create new biotechnological applications.