Bacteriophage Mu Transposition and the Role of Gyrase Binding Sites

细菌病毒Mu由于其既是病毒又是转座子，在转座子中因其大尺寸和高转座频率而不寻常。在裂解循环期间，37.2kb Mu DNA的扩增通过在细菌类核内发生的一系列复制性转座事件发生，尽管该体的复杂结构施加了限制。对类核内前噬菌体DNA末端突触的潜在问题的担忧（转座过程的早期步骤）导致了在Mu基因组中心发现有效复制所需的强促旋酶结合位点（SGS）的研究。 进行了广泛的搜索，以找到染色体或质粒的网站，可以取代的Mu复制的SGS。没有发现其他网站，集中注意力在什么是不寻常的SGS。该项目重点关注该模型提出的两个重要问题：1）Mu位点如何促进Mu原噬菌体末端的突触，2）为什么需要一种新的机制来促进突触？ 第一个问题将通过确定穆遗址的特殊性或独特性来解决。 一个详细的遗传和生物化学分析的SGS和其他强的促旋酶结合位点正在进行的目标是定义的SGS的元素，负责其功能在Mu DNA复制的能力。第二个问题正在解决探索的因素，如转座酶分子的Mu前噬菌体的末端的结合，这是负责在Mu复制的SGS的情况下的长期延迟。 这些研究旨在深入了解病毒DNA复制的机制以及DNA结构在生物学功能中的重要性。特别感兴趣的是DNA拓扑结构在功能调节中的作用。

Pato 9727991 The bacterial virus Mu, by virtue of its being both a virus and a transposon, is unusual among transposons in its large size and its high frequency of transposition. Amplification of the 37.2 kb Mu DNA during the lytic cycle occurs by a series of replicative transposition events which take place within the bacterial nucleoid, despite the constraints imposed by the complex structure of that body. Concerns about potential problems with synapsing the ends of prophage DNA within the nucleoid, an early step in the transposition process, led to studies which uncovered a strong gyrase binding site (SGS) in the center of the Mu genome that is required for efficient replication. An extensive search was undertaken to find chromosomal or plasmid sites which could replace the SGS in Mu replication. No other sites have been found, focusing attention on what is unusual about the SGS. This project focuses on two important questions raised by the model: 1) How does the Mu site promote synapsis of the Mu prophage ends and 2) Why is a novel mechanism required for promoting the synapsis? The first question will be addressed by determining what is special or unique about the Mu site. A detailed genetic and biochemical analysis of the SGS and of other strong gyrase binding sites is being performed with the goal of defining the elements of the SGS that are responsible for its ability to function in Mu DNA replication. The second question is being addressed by exploring the factors, such as the binding of transposase molecules to the ends of a Mu prophage, that are responsible for the long delay in Mu replication in the absence of the SGS. These studies are designed to provide insights into the mechanism of viral DNA replication and the importance of DNA structure in biological function. Of particular interest is the role of DNA topology in the modulation of function.