T-DNA INTEGRATION DURING CROWN GALL TUMORIGENESIS

在冠瘤发生过程中，农杆菌的一个特定片段 Tumefaciens肿瘤诱导(Ti)质粒，称为T-DNA，整合到 种植核DNA。类似的23个碱基对(Bp)在每个末端都有直接重复 T区代表T-DNA边界。T-DNA传播(转移和 集成)只需要在顺序列中的右侧重复，但24个BP 序列，称为超速，通常在右侧重复很多 刺激了这一过程。尽管右边框重复在一个边框中运行效果最好 方向，超速驱动功能在任何一个方向。要了解 T-DNA的传播机制，我们将检测分子 在T-DNA传递过程中形成并决定其作用的中间体 超速和边界重复在他们的队形中发挥作用。通过基因 和生化实验，我们将识别与之相互作用的蛋白质 这些序列。为了了解超速驱动是如何起作用的，我们将探究 其位置对刺激T-DNA边界功能能力的影响。 研究T-DNA整合到植物中的分子机制 ，我们将描述在T-DNA过程中宿主DNA发生的变化 整合。 我们的实验将有助于理解独特而重要的 冠冠过程中细菌和宿主DNA之间发生的重组事件 他们将改进T-DNA作为一种模型系统 研究肿瘤发生、基因表达和宿主与病原体的相互作用。 这项研究将确定建立肿瘤所需的因素和 可能会提出阻止肿瘤发生的方法，这是一个重要的目标，因为 冠胆肿瘤发生与病毒诱发肿瘤的相似性 动物。了解T-DNA整合的机制也可能会 腺病毒整合的机制，这一过程可能 涉及相似的分子事件。农杆菌和立克次体(细菌 引起战壕热、Q热和落基山斑疹热 人类)有相似的生活方式(与真核生物密切相关 与毒力相关的宿主细胞和质粒)除了非常 亲缘关系密切。因此，根癌农杆菌可以作为一个模式。 用于立克次体致病以及人类肿瘤的发生。

During crown gall tumorigenesis a specific segment of the Agrobacterium tumefaciens tumor-inducing (Ti) plasmid, called the T-DNA, integrates into plant nuclear DNA. Similar 23 base-pair (bp) direct repeats at each end of the T region signal the T-DNA borders. T-DNA transmission (transfer and integration) requires only the right-hand repeat in cis, but a 24 bp sequence, called overdrive, which normally flanks right repeats greatly stimulates the process. Although right border repeats function best in one orientation, overdrive functions in either orientation. To understand the mechanism of T-DNA transmission, we will examine the molecular intermediates which form during T-DNA transmission and determine the roles overdrive and the border repeats play in their formation. Through genetic and biochemical experiments we will identify proteins which interact with these sequences. To understand how overdrive acts, we will exmine the effect of its location on the ability to stimulate T-DNA border function. To examine the molecular mechanism by which T-DNA integrates into plant DNA, we will characterize changes that occur in host DNA during T-DNA integration. Our experiments will contribute to understanding the unique and important recombination events that occur between bacterial and host DNA during crown gall tumorigenesis, and they will improve the T-DNA as a model system for studying tumorigenesis, gene expression, and host-pathogen interactions. This research will identify factors required for tumor establishment and may suggest ways to block tumorigenesis, an important goal given the similarities between crown gall tumorigenesis and viral tumor induction in animals. Understanding the mechanism of T-DNA integration may also shed light on the mechanism of adenovirus integration, a process that may involve similar molecule events. Agrobacterium and rickettsiae (bacteria which cause trench fever, Q fever, and Rocky Mountain spotted fever in humans) share lifestyle similarities (close association with eukaryotic host cells and plasmids associated with virulence) in addition to a very close phylogenetic relationship. Thus, A. tumefaciens may serve as a model for rickettsial pathogenesis as well as human tumorigenesis.