Chemoreception of aromatic acids by Pseudomonas putida

芳香族化合物作为植物材料（木质素）的主要成分和工业活动的有毒副产品在环境中大量存在。 虽然我们对这些化合物是如何降解的有所了解，但对细菌如何在环境中检测它们却知之甚少。 包括假单胞菌在内的几种能动细菌对芳香酸有很强的吸引力。 我们将研究恶臭假单胞菌对4-羟基苯甲酸和相关芳香酸的趋化作用的分子基础。 最近，这些化合物的一个明显的化学受体编码基因被克隆和测序。 芳香酸受体是一种膜蛋白，其结构不同于已描述的其他细菌化学受体。 我们将尝试通过后生作用来定义芳香酸化学感受器的化学感受信号结构域，然后评估该蛋白的甲基化和/或磷酸化在化学感受信号转导/适应中的可能作用。将确定化学感受器基因邻近区域的遗传组织，并定义化学感受器基因表达的调控要求。 最后，恶臭假单胞菌趋化性所需的基因将被克隆和测序，作为将芳香酸化学感受器与这种细菌的中央趋化机制“联系起来”的一种手段。 由于芳香酸的化学感受器蛋白似乎具有独特的结构特征，我们的研究将拓宽目前关于细菌化学感受和感觉转导机制的概念。 %许多环境污染物以苯环为主要结构成分，被归类为芳香族化合物。 细菌具有从自然界中去除芳香族化合物的能力，人们对利用这种能力开发用于有毒废物管理的生物修复新方法非常感兴趣。 为了有效地利用生物修复，我们需要了解细菌如何降解芳香族化合物，我们还需要知道细菌首先是如何感知自然界中的化合物的。 本计画将探讨细菌对芳香族化合物的行为反应（趋化性）。 我们研究的细菌是能动的，可以在周围环境中检测到这些化合物作为食物。 我们的主要实验计划将是培育出不能感知化合物的突变体，然后确定负责的细胞中缺失了什么。 一旦确定，我们将克隆和分析基因。 如果我们能够理解芳香族化合物（涉及一个或多个受体）的吸引机制，那么就有可能设计出将细菌招募到生物修复位点的策略。 ***

Harwood 9316257 Aromatic compounds are abundant in the environment as major components of plant material (lignin) and as toxic by-products of industrial activities. Although we know something about how these compounds are degraded, not much is understood about how bacteria detect them in the environment. Several genera of motile bacteria, including Pseudomonas, have a strong attraction to aromatic acids. We will study the molecular basis for chemotaxis to 4- hydroxybenzoate and related aromatic acids in P. putida. Recently, a gene encoding an apparent chemoreceptor for these compounds was cloned and sequenced. The aromatic acid receptor is a membrane protein with a structure different from other bacterial chemoreceptors that have been described. We will attempt to define the chemosensory signaling domain of the aromatic acid chemoreceptor by metagenesis, and then asses a possible role for methylation and/or phosphorylation of the protein in chemosensory signal transduction/adaptation. The genetic organization of the region contiguous to the chemoreceptor gene will be determined, and the regulatory requirements for chemoreceptor gene expression will be defined. Finally, genes that are required for P. putida chemotaxis will be cloned and sequenced as a means of putting the aromatic acid chemoreceptor "in context" with the central chemotaxis machinery of this bacterium. Since the chemoreceptor protein for aromatic acids appears to have distinctive structural characteristics, our studies will broaden current concepts about mechanisms of bacterial chemoreception and sensory transduction. %%% Many environmental pollutants have a benzene ring as the main structural constituent and are classified as aromatic compounds. Bacteria have the ability to remove aromatic compounds from nature, and there is great interest in harnessing this ability to develop new methods for bioremediation to use in toxic waste management. To effectively use bioremediation, we need to understand how bacteria degrade aromatic compounds, and we also need to know how bacteria sense the compounds in nature in the first place. This project will examine the behavioral responses (chemotaxis) of bacteria to aromatic compounds. The bacteria we study are motile and can detect these compounds as food in their surroundings. Our main experimental plan will be to develop mutants that don't sense the compounds and then determine what is missing in the cell that is responsible. Once identified, we will clone and analyze the gene(s). If we can understand the mechanism(s) responsible for attraction to aromatic compounds (which involves one or more receptors), then it may be possible to devise strategies to recruit bacteria to bioremediation sites. ***