Osmoprotection of Pseudomonas Syringae During its Association with Plants: Role of the BetT and OpuC Transporters

为了科普其环境中的波动渗透压，微生物通常产生用于摄取抗微生物保护剂化合物的转运蛋白。这些化合物，包括甘氨酸甜菜碱及其前体胆碱，广泛存在于植物中;然而，很少有人知道它们对植物微生物区系的可用性。基于植物上微生物栖息地中水的可利用性的大波动和可能存在的植物来源的植物保护剂，通过转运蛋白介导的吸收的渗透适应可能对植物相关细菌的生态学是重要的。了解这些化合物在细菌生态学中的作用需要了解介导摄取的转运蛋白。已在假单胞菌中鉴定出两种转运蛋白，其负责高渗胁迫下甘氨酸甜菜碱及其前体胆碱的全部或绝大部分摄取。该生物是一种叶面病原体，一种常见的植物居民，也是研究细菌-植物相互作用的模式生物。本项目的目标是表征这两种转运蛋白，命名为BetT和OpuC，并评估它们在植物中的适应性，生长和存活中的作用。为了实现这一目标，BetT和OpuC的功能特性，包括它们的动力学参数和溶质特异性，将被表征，它们在转录和转录后水平的调节将被检查，并且它们对具有各种天然和操纵浓度的植物保护剂的P.这些信息将有助于填补假单胞菌属物种中摄取介导的细菌适应信息的空白，并将提供细菌如何熟练地利用它们所适应的生态位的见解。这些研究产生的知识与改善食品安全和生产有关，包括控制植物上的动植物病原体、改善植物疾病预测和控制以及预测经改造以增强耐旱和耐盐胁迫能力的转基因植物的非目标效应的战略。该项目将通过培训一名博士后研究员、一名研究生和四名本科生（其中至少一名为少数民族学生）、为中学生和国际农业科学家开展外联活动以及为本科微生物学课程开展课程强化活动，为教育做出贡献。

To cope with fluctuating osmolarity in their environment, microorganisms often produce transporters for the uptake of osmoprotectant compounds. These compounds, including glycine betaine and its precursor choline, occur widely in plants; however, little is known of their availability to the plant microflora. Osmoadaptation via transporter-mediated uptake may be important to the ecology of plant-associated bacteria based on the large fluctuations in water availability in microbial habitats on plants and the likely presence of plant-derived osmoprotectants. Understanding the role of these compounds in bacterial ecology requires knowledge of the transporters that mediate uptake. Two transporters that are responsible for all, or the vast majority, of the uptake of glycine betaine and its precursor choline under hyperosmotic stress have been identified in Pseudomonas syringae. This organism is a foliar pathogen, a common plant resident, and a model organism for studying bacterial-plant interactions. The goal of this project is to characterize these two transporters, designated BetT and OpuC, and evaluate their role in the osmoadaptation, growth and survival of P. syringae in plants. To address this goal, the functional characteristics of BetT and OpuC, including their kinetic parameters and solute specificity, will be characterized, their regulation at the transcriptional and post-transcriptional levels will be examined, and their significance to P. syringae ecology on plants that have various natural and manipulated concentrations of osmoprotectants will be identified. This information will help fill a void of information on uptake-mediated osmoadaptation in Pseudomonas species and will provide insights into how bacteria so expertly exploit the ecological niches to which they are adapted. The knowledge generated in these studies is relevant to improving food safety and production, including strategies for controlling plant and animal pathogens on plants, improving plant disease forecasting and control, and predicting non-target effects of transgenic plants engineered for enhanced tolerance to drought and salinity stress. This project will contribute to education through training a postdoctoral researcher, a graduate student, and four undergraduate students, at least one of which is expected to be a minority student; outreach activities for secondary school students and international agricultural scientists; and curriculum strengthening activities for an undergraduate microbiology program.