LONG RANGE INTERACTIONS IN MU AND BACTERIAL DNA

描述：DNA结构域的形成对真核生物和 原核细胞一样。 活细胞内DNA运动的动力学 是生物学的核心问题 当DNA被复制和转录时， DNA双链体的扭曲、转动、缠结和解开， 一个主要的问题是影响细胞酶的功能， 比如转录、基因重组、染色体分离， 复制的 结构域调控支持细胞发育和基因 人类（即造血）和细菌等多种生物体的调节 (i.e.适应恶劣的环境）。 一种方法，它使用伽马 δ位点特异性重组途径已被开发用于研究 超螺旋动力学和活细胞内的域结构。 该分析 可以在细菌基因组中的任何所需点进行。 使用分辨率系统，超螺旋结构域已被证明是 丰富的和放置随机超过10%的细菌染色体。 为 细胞呈指数增长，染色体上的两个位点 将通过超螺旋运动相互作用，符合一阶函数; 是每15 kb距离存在障碍的概率为50 分隔两个站点。 这项建议有三个具体目标。 首先，通过扩展的方法研究了磁畴结构的全局模式， 调查覆盖30%的基因组。 细胞分裂的两个临界点 控制将包括在调查的起源和终点的DNA 复制的 第二，使用链交换的动力学分析， 这些研究将计算阻止动态DNA运动的障碍 沿着染色体。 此外，还将进行基因筛查， 找到调节结构域数量的基因组。 两个基本 细菌中的基因，DNA旋转酶和拓扑异构酶IV， 这个屏幕。 其他基因将被绘制和表征。 第三个目标 涉及的理论是DNA链的结和缠结构成了 阻碍了长距离DNA动力学。 特殊的转座子将被制造出来， 找到并计数染色体不同区域的结。

DESCRIPTION: DNA domain formation is critical for eukaryotic and prokaryotic cells alike. The dynamics of DNA movement inside a living cell is a central problem in biology. As DNA is replicated and transcribed, the twisting, turning, tangling, and untangling of the duplex strands of DNA is a major problem that impinges on cellular enzymes that perform functions like transcription, genetic recombination, chromosome segregation, and replication. Domain regulation underpins cell development and gene regulation in organisms as diverse as man (i.e. hematopoiesis) and bacteria (i.e. in adapting to a harsh environment). A method that uses the gamma delta site-specific recombination pathway has been developed to study supercoil dynamics and domain structure inside living cells. This analysis can be performed at any desired point in the bacterial genome. Using the resolution system, supercoiling domains have been shown to be abundant and place stochastically over 10% of the bacterial chromosome. For cells growing exponentially, the probability that two sites in a chromosome will interact through supercoil movement fits a first order function; there is a 50% probability that a barrier will exist for each 15 kb of distance separating two sites. In this proposal there are three specific aims. First, the global pattern of domain structure will be studied by expanding the survey to cover 30% of the genome. Two critical points of cell division control will be included in the survey the origin and terminus of DNA replication. Second, using a kinetic analysis of the strand exchange process, these studies will count barriers that stop dynamic DNA movement along the chromosome. In addition, a genetic screen will be carried out to find the set of genes that modulate the number of domains. Two essential genes in bacteria, DNA gyrase and Topoisomerase IV, have both turned up in this screen. Other genes will be mapped and characterized. The third aim involves the theory that knots and tangling of DNA strands pose a major impediment to long range DNA dynamics. Special transposons will be built to find and count knots in different regions of the chromosome.