INTERACTIONS OF HELIX LOOP HELIX TRANSCRIPTION FACTORS

描述(摘自《申请》)：RNA聚合酶II的基因表达活性由一组蛋白质(转录因子)调节，这些蛋白质(转录因子)决定哪些基因被转录。最具特征的转录因子是螺旋-环-螺旋(HLH)蛋白。HLH蛋白通常由一个基本氨基酸序列、一个螺旋-环-螺旋结构域和一个亮氨酸七肽重复序列或亮氨酸拉链组成。尽管HLH转录因子蛋白的一般作用机制是已知的，但关于这些蛋白如何相互作用及其DNA靶标的定量解决方案数据很少。Myc、Max、Mad和Usf亚群通常作为转录激活因子发挥作用，但myc可能需要形成myc-Max异源二聚体才能实现激活。Mad-Max异源二聚体能够与myc共识序列结合，并作为抑制子发挥作用。这些蛋白质调节各种细胞基因，包括有时起癌基因和引起恶性肿瘤的作用。这项研究的长期目标是了解并导致恶性肿瘤。这项研究的长期目标是了解这些蛋白质如何识别一些但不是所有的DNA靶序列；在某些情况下能够作为抑制物，在其他情况下能够作为激活物；以及了解这些过程的动力学和限速步骤，以便制定更详细的基因调控机制。荧光光谱将被用来确定这些蛋白质与目标DNA序列相互作用的平衡结合亲和力和动力学性质，以及这些蛋白质与目标DNA序列相互作用和相互作用的每种性质。结构数据将有助于理解与DNA结合亲和力的差异与目标E-box侧翼序列的变化以及蛋白质修饰的影响。等电点将决定抑制子复合体是否与DNA更紧密地结合，并阻止转录因子，而不与DNA结合。使用USF作为这类蛋白质的一个例子，将制定更详细的转录调控动力学机制的确定。

DESCRIPTION (Adapted from Application): Gene expression by RNA polymerase II activity is regulated by a set of proteins (transcription factors) that determine which genes are to be transcribed. The best characterized of the transcription factors are the helix-loop-helix (HLH) proteins. The HLH proteins typically consist of a basic amino acid sequence,, a helix-loop-helix domain, and a leucine heptad repeat or leucine zipper. Even though the general mechanism of action of HLH transcription factor proteins is known, there is little quantitative solution data on how these proteins interact with each other and their DNA targets. The subgroup myc, Max, Mad, and USF often function as transcriptional activators, but myc may require formation of a myc-Max heterodimer to achieve activation. The Mad-Max heterodimer has the ability to bind to the myc consensus sequence and act as a repressor. These proteins regulate a variety of cellular genes, including sometimes acting as oncogenes and causing malignancy. The long-term goal of this research is to understand and causing malignancy. The long-term goal of this research is to understand how these proteins recognize some but not all DNA target sequences; are able to act as repressors in some cases and activators in other cases; and to understand the kinetics and rate-limiting steps for these processes in order to formulate a more detailed mechanism of gene regulation. Fluorescence spectroscopy will be used to determine equilibrium binding affinity and kinetic properties of these proteins interacting with target DNA sequences and each properties of these proteins interacting with target DNA sequences and each other. Structural data will aid in understanding differences in binding affinity for DNA with variation in the flanking sequences of the target E-BOX and the effects of modification of the protein. The PI will determine if repressor complexes bind more tightly to DNA and block transcription factors and do not bind to DNA. Using USF as an example of this class of proteins, a determination of a more detailed kinetic mechanism of transcriptional regulation will be formulated.