INTERACTIONS BETWEEN AGROBACTERIUM AND HOST PLANTS

根癌农杆菌，一种革兰氏阴性土壤细菌， 与高等植物的寄生关系，将被用来理解 致病微生物及其宿主如何相互作用， 提供关于细胞和生物体如何获得的基本见解， 处理来自周围环境的信息 感生土壤杆菌 易受感染的受伤植物通过感知一类 酚类化合物，而它的感觉肿瘤植物组织，是一个 通过感知一类衍生的氨基， 酸和糖称为阿片类。 两种蛋白质（VirA和VirG） 第一个识别系统所需的，我们将测试 假设其中一个是环境传感器，而 另一个是转录激活因子。 我们将决定是否 假定的环境传感器具有用于诱导物的结合位点，并且 它（像几种同源蛋白质）是否能够 自磷酸化 我们还将在每一个点突变， 组成性活性蛋白质。 为了促进所有这些 研究中，我们将尝试在大肠杆菌中重建这一调节系统。 杆菌 我们亦会研究另一套规管制度， virG启动子，识别顺式和反式作用元件。 另一组T质粒编码的基因可被冠瘿碱诱导， 对介导这种反应的蛋白质知之甚少。 我们将 鉴定调节阿片诱导型所需的反式作用因子 基因，并对其进行亚克隆和测序。 最后，也是最重要的， 将鉴定和表征由冠瘿碱诱导的新基因座。 通过 分析其预测的氨基酸序列并通过表征 我们将通过这些基因的突变来了解 它们在维持这种寄生关系中的作用。

Agrobacterium tumefaciens, a gram negative soil bacterium that can live in parasitic association with higher plants, will be used to understand how disease-causing microbes and their hosts interact, and may also provide fundamental insights about how cells and organisms gain and process information from their surroundings. Agrobacterium senses wounded plants susceptible to infection by perceiving a class of phenolic compounds, while it senses tumorous plant tissues that are a consequence of infection by perceiving a class of derivatized amino acids and sugars known as opines. Two proteins (VirA and VirG) are required for the first of these recognition systems, and we will test the hypotheses that one of these is an environmental sensor, while the other is a transcriptional activator. We will determine whether the putative environmental sensor has a binding site for inducers, and whether it (like several homologous proteins) is capable of autophosphorylation. We will also obtain point mutants in each of these proteins that are constitutively active. To facilitate all these studies, we will attempt to reconstruct this regulatory system in E. coli. We will also study a separate regulatory system which regulates the virG promoter, identifying both cis- and trans-acting elements. Another set of T-plasmid encoded genes is inducible by opines, and little is known about the proteins mediating this response. We will identify trans-acting factors required to regulate opine-inducible genes, and subclone and sequence them. Finally and most importantly we will identify and characterize new loci which are induced by opines. By analyzing their predicted amino acid sequence and by characterizing stains with mutations in each of these genes we will gain insights about their role in the maintenance of this parasitic association.