Role of DNA Binding Linked Protein-Protein Interactions in Gene Regulation

调节蛋白与独特DNA位点的特异性结合是调节转录起始的基础。 这些研究涉及蛋白质-蛋白质相互作用在介导这些过程中的作用。 一个目的是确定二聚体自组装和耦合相互作用如何介导DNA结合协同性。 二聚体可以在溶液中自组装形成八聚体作为直接产物。 四聚体，长期以来被认为是介导成对协同效应的物种，是协同反应中的次要中间体。 因此，耦合相互作用负责选择溶液物质分布的次要组分作为DNA结合分布的主要组分，因此对调节至关重要。 通过研究阻遏物自组装与操纵子结合的热力学循环，可以确定什么样的溶液组装有助于协同性，以及蛋白质和DNA介导的偶联有助于什么。 第二个目标解决蛋白质-蛋白质相互作用如何有助于阻遏物二聚体的三个OR操作位点的差异亲和力。 现在已经确定，结合两半假回文操纵子的单独亚基不能独立地与DNA相互作用。 单个亚基-半位点相互作用之间的偶联涉及阻遏物和DNA构象变化。 相关的结构和化学变化，导致二聚体界面与二聚体的稳定性和运营商结合特异性的影响，将导致亚基间通信和蛋白质结构变化，有助于差分运营商亲和力的机制的理解。 ***

9513661 Senear Sequence specific binding of regulatory proteins to unique DNA sites is the basis for regulation of transcriptional initiation. These studies are involved with the roles of protein-protein interactions in mediating these processes. One aim is to determine how dimer self-assembly and coupled interactions mediate DNA binding cooperativity. Dimers can self-assemble in solution to form octamers as the immediate product. Tetramers, the species long believed to mediate pairwise cooperativity, are minor intermediates in a concerted reaction. Therefore, coupled interactions are responsible for selecting a minor component of the solution species distribution as a major component of the DNA-bound distribution, hence as critical to regulation. By investigating the thermodynamic cycles that couple repressor self-assembly to operator binding, one can determine what solution assembly contributes to cooperativity and what protein and DNA mediated coupling contribute. A second aim addresses how protein-protein interactions contribute to differential affinity of repressor dimers for the three OR operator sites. It is now well established that the separate subunits that bind the two halves of the pseudo-palindromic operators do not interact independently with DNA. Coupling between the individual subunit-half site interactions involves both repressor and DNA conformational changes. Correlating structural and chemical changes resulting in the dimer interface with effects on dimer stability and operator binding specificity will lead to an understanding of the mechanisms of inter-subunit communication and protein structural changes that contribute to differential operator affinity. ***