Molecular Dissection of Tn7's Targeting of DNA Metabolism

这个项目剖析了细菌转座子TN7是如何识别与DNA复制和重组相关的靶点的。转座子是能够在生物体基因组内移动的离散DNA元件。转座子在细菌的进化中很重要，通常通过对抗生素和金属的抗药性或通过新的降解途径使其宿主有机体能够生活在新的环境中。转座子Tn7由于其高度进化的能力选择与活跃的DNA复制相关的插入位点而引起人们的特别关注。Tn7使用元件编码的蛋白质TnsE，通过识别与DNA复制相关的因素，优先将转座定位为能够在细胞之间移动的质粒。Tn7识别可移动质粒作为插入目标的能力可能有助于该元件向其他细菌的扩散。Tn7转座还识别与DNA双链断裂修复相关的结构，并允许Tn7优先指导DNA复制终止的转座。这个项目的工作将集中在了解TnsE的各种生化活动以及这些活动驻留在蛋白质中的哪里。在该项目中，将剖析以前发现的转座活性增加的突变以及新分离的TnsE突变。其他工作将确定解释TnsE介导的转座事件在诱导的DNA双链断裂周围分布的分子过程。清楚地了解Tn7如何识别某些靶标将有助于更好地理解转座子在进化中的作用以及所有活着的生物体中的DNA复制和修复过程。本科生的利用是本研究项目的一个重要组成部分。

This project dissects how the bacterial transposon Tn7 recognizes targets associated with DNA replication and recombination. Transposons are discrete DNA elements that are able to move within the genome of an organism. Transposons are important in the evolution of bacteria and are often responsible for allowing their host organism to live in new environments through resistance to antibiotics and metals or by novel degradation pathways. The transposon Tn7 is of special interest because of its highly evolved ability to select insertion sites associated with active DNA replication. Tn7 uses the element-encoded protein TnsE to preferentially target transposition into plasmids capable of moving between cells by recognizing factors associated with DNA replication. The ability of Tn7 to recognize mobile plasmids as insertion targets likely aids in the dispersal of the element to other bacteria. Tn7 transposition also recognizes structures associated with the repair of DNA double-strand breaks and allows Tn7 to preferentially direct transposition where DNA replication terminates. Work in this project will focus on understanding the various biochemical activities of TnsE and where these activities reside in the protein. In the project, previously identified mutations with increased transposition activity as well as newly isolated TnsE mutations will be dissected. Additional work will determine the molecular process that accounts for the distribution of TnsE-mediated transposition events around induced DNA double-strand breaks. A clear understanding of how Tn7 recognizes certain targets will lead to a better understanding of the role of transposons in evolution and the processes of DNA replication and repair in all living organisms. The utilization of undergraduates is an important component of this research project.