Complex Sensory Network Coordinating Interactions of Pseudomonas solanacearum with Host Plants

协调青枯菌与寄主植物相互作用的复杂感觉网络

• 批准号: 9419582
• 负责人: Mark Schell
• 金额: $ 28.96万
• 依托单位: University of Georgia Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-04-01 至 1999-03-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9419582&HistoricalAwards=false
• 关键词: Complex; Sensory; Network; Coordinating; Interactions

9419582 Schell Pseudomonas solanacearum is a soil-borne phytopathogen that causes a lethal wilting disease of diverse plants, in part due to production of an unusual exopolysaccharide (EPS 1) and numerous extracellular proteins (EXPs). Levels of many virulence factors are controlled by a complex sensory network whose size, organization, and other properties set it apart from others found in prokaryotes. The network controls switching between two morphotypes, each probably specialized for survival in different ecological niches (plant vs. soil), and also modulates transcription of genes for EPS I (eps) and other virulence factors in response to multiple environmental signals. The focus of this work is on the unique molecular aspects of the network, and on the biochemical and physiological functions of some of its unusual regulated targets. The biochemical mechanism of the network's unique signal-integrator protein, XpsR, that in conjunction with the VsrC response regulator coordinates transcription at the eps promoter in response to three different signals is being explored, mutagenesis and in vivo footprinting will be used to define promoter sequences and conditions required for binding and transcription activation by XpsR and/or VsrC to gain insight into their interactions with each other and/or the promoter. Powerful screening methods will be used to isolate mutant alleles of xpsR and vsrC that activate eps transcription independently of each other, and nonfunctional xpsR alleles. DNA sequence analysis and characterization of these mutants will identify important domains of XpsR and VsrC that interact to link individual signal transduction systems into the larger network. Another network component regulating production of EPS I is vsrAD which appears to also regulate important penes that are required for stem colonization. Another network-regulated gene, tek, encodes an unusual 59-kDa lipoprotein that is externally processed to release its basic 28-kDa C-terminus, which becomes th e major EXP of P. solanacearum. Using antiserum and various mutants synthesis, processing, localization, and fate of labelled Tek polypeptides is being monitored their function and apparent association with EPS I and virulence. rgnll is also regulated by the network and appears to prevent inhibition of EPS I production by certain environmental conditions. The mechanism of this and its physiological significance are being investigated by: DNA sequence analysis, testing the effect of rgnll mutations on expression of eps and related genes, and characterizing in more detail what molecules and conditions affect rgnll function. Finally, DNA sequence analysis of eps are being used to gain further insight into its novel enzymes, their role in biosynthesis and decoration of EPS 1, and their physiological functions. %%% Research on this bacterium that causes disease in plants could lead to a lessening of damage done to plants by bacterial infection. ***

9419582 Schell Pseudomonas solanacearum 是一种土传植物病原体，可导致多种植物致命的枯萎病，部分原因是产生不寻常的胞外多糖 (EPS 1) 和大量胞外蛋白 (EXP)。许多毒力因子的水平由复杂的感觉网络控制，其大小、组织和其他特性使其与原核生物中发现的其他因子不同。该网络控制两种形态类型之间的切换，每种形态类型可能专门用于在不同的生态位（植物与土壤）中生存，并且还根据多种环境信号调节 EPS I (eps) 和其他毒力因子的基因转录。这项工作的重点是网络的独特分子方面，以及其一些不寻常的调控靶标的生化和生理功能。 网络独特的信号整合蛋白 XpsR 的生化机制正在探索中，该机制与 VsrC 响应调节器结合，协调 eps 启动子处的转录以响应三种不同的信号，将使用诱变和体内足迹来定义 XpsR 和/或 VsrC 结合和转录激活所需的启动子序列和条件，以深入了解它们的相互作用 与彼此和/或发起人。将使用强大的筛选方法来分离彼此独立地激活 eps 转录的 xpsR 和 vsrC 突变等位基因，以及非功能性 xpsR 等位基因。 DNA 序列分析和这些突变体的表征将识别 XpsR 和 VsrC 的重要结构域，它们相互作用将单个信号转导系统连接到更大的网络中。另一个调节 EPS I 产生的网络组件是 vsrAD，它似乎也调节茎定植所需的重要阴茎。 另一个网络调节基因 tek 编码一种不寻常的 59-kDa 脂蛋白，该脂蛋白经过外部处理以释放其基本的 28-kDa C 末端，成为青枯菌的主要 EXP。使用抗血清和各种突变体合成、加工、定位和标记的 Tek 多肽的命运正在监测它们的功能以及与 EPS I 和毒力的明显关联。 rgnll 也受到网络的调节，似乎可以防止某些环境条件对 EPS I 产生的抑制。其机制及其生理意义正在通过以下方式进行研究：DNA序列分析，测试rgnll突变对eps和相关基因表达的影响，并更详细地描述哪些分子和条件影响rgnll功能。最后，eps 的 DNA 序列分析可用于进一步了解其新型酶、它们在 EPS 1 生物合成和装饰中的作用及其生理功能。 %%% 对这种引起植物疾病的细菌的研究可能会减少细菌感染对植物造成的损害。 ***