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

9513661调控蛋白与独特的脱氧核糖核酸位点的特异结合是转录启动调控的基础。这些研究涉及蛋白质-蛋白质相互作用在调节这些过程中的作用。一个目的是确定二聚体自组装和耦合相互作用如何调节DNA结合的协同性。二聚体可以在溶液中自组装形成八聚体作为直接产物。四聚体是协同反应中的次要中间体，长期以来一直被认为是调节成对协同作用的物种。因此，耦合作用负责选择溶液物种分布的一小部分作为DNA结合分布的主要成分，因此对调节至关重要。通过研究阻遏子自组装与操纵子结合的热力学循环，人们可以确定什么溶液组装有助于协同作用，以及什么蛋白质和DNA介导的偶联作用。第二个目的是研究蛋白质-蛋白质相互作用如何影响阻遏因子二聚体对三个OR操作位点的不同亲和力。现在公认的是，连接假回文操作符的两个半部分的单独的亚基并不独立地与DNA相互作用。单个亚基与半个位点相互作用之间的偶联涉及到抑制物和DNA构象的变化。将导致二聚体界面的结构和化学变化与对二聚体稳定性和操纵子结合特异性的影响相关联，将有助于理解有助于差异操纵子亲和力的亚基间通信和蛋白质结构变化的机制。***

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. ***