LONG RANGE INTERACTIONS IN MU AND BACTERIAL DNA

描述：DNA结构域的形成对真核生物和 原核细胞相似。活细胞内DNA运动的动力学 是生物学中的一个中心问题。当DNA被复制和转录时， 缠绕、翻转、缠绕和解开DNA的双链是 影响执行功能的细胞酶的一个主要问题 如转录、基因重组、染色体分离，以及 复制。结构域调控是细胞发育和基因的基础 对人(即造血)和细菌等不同生物的调节 (例如，在适应恶劣环境方面)。一种使用伽马的方法 已经开发了Delta位点特异性重组途径来研究 活细胞内的超线圈动力学和磁区结构。这一分析 可以在细菌基因组中的任何所需位置进行。 使用分辨率系统，超螺旋结构域已被证明是 丰富并随机放置在细菌染色体的10%以上。为 细胞呈指数增长，一条染色体上两个位置的概率 将通过超级线圈运动符合一阶函数； 每15 kb的距离有50%的概率会存在障碍 分隔两个地点。在这项建议中，有三个具体目标。 首先，通过扩展来研究领域结构的全球格局 这项调查覆盖了30%的基因组。细胞分裂的两个临界点 控制将包括在调查中的DNA的来源和终点 复制。第二，使用链交换的动力学分析 过程中，这些研究将计算阻止动态DNA移动的障碍 沿着染色体。此外，还将进行基因筛查，以 找出调节结构域数量的一组基因。两个基本要素 细菌中的基因，DNA旋转酶和拓扑异构酶IV，都出现在 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链的打结和缠绕构成了 远程DNA动力学的障碍。将建造特殊的转座子来 找出并计算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.