Collaborative Research: Chemotactic signaling in Sinorhizobium meliloti symbiotic plant host interaction

合作研究：苜蓿中华根瘤菌共生植物宿主相互作用中的趋化信号传导

• 批准号: 2128233
• 负责人: Ann Stock
• 金额: $ 39.46万
• 依托单位: Rutgers, The State University of New Jersey-RBHS-Robert Wood
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2128233&HistoricalAwards=false
• 关键词: Collaborative; Research; Chemotactic; signaling; Sinorhizobium

Chemotaxis enables motile bacteria to move away from harmful and towards beneficial chemicals. One unique group of motile soil bacteria are rhizobia, which can engage in specific symbiotic relationships with leguminous plants such as peas, soy beans, and alfalfa. This symbiosis supplies the host plant with nitrogen, which is the most limiting nutrient for plant growth. The process of chemotaxis allows rhizobia to recognize and move towards its host, which improves the symbiotic relationship, and consequently, enhances plant growth. Multiple chemoreceptor proteins are being used by rhizobia to sense a wide spectrum of chemical compounds secreted by the host plants. However, little is known about the specific processes involved in the regulation of sensitivity and adaptation, which are essential features for an effective chemotactic response. The overarching goal of this project is to decode the pathway that controls stimuli adaptation. Outcomes will transform our current concepts of the biology of bacterial chemotaxis and their interaction with their eukaryotic hosts. The results of this research can directly benefit future agricultural and environmental issues by potentially reducing the use of artificial fertilizers, resulting in less expensive and less polluting agriculture. Broader Impacts activities include the intrinsic merit of the research as nitrogen fixation is one of the most important processes in the biosphere. In addition, the project will involve the interdisciplinary training of graduate students. The team is committed to mentoring graduate and undergraduate students, especially underrepresented populations and women. Public outreach activities include hands-on demonstrations for elementary and high school students, both on- and off-campus, and involvement of undergraduate and high school students in research.The chemotaxis system of the model plant symbiont Sinorhizobium meliloti evolved a greater complexity than that of enteric bacteria. Although several unique components and features controlling chemotaxis have been recently uncovered, regulation of pathway sensitivity and stimuli adaptation are unknown. The aim of this research project is to elucidate the receptor modification system, which plays a pivotal role in this process. Specifically, the function of a novel chemotaxis protein, CheT, which unprecedentedly interacts with a conserved element of the adaptation pathway, will be deciphered. First, the investigators will characterize the chemotactic pathway controlling adaptation. Two chemoreceptors with a central role in host-plant sensing, namely amino acid sensor McpU and betaine sensors McpX, will serve as models because they are expected to exhibit different modes of interaction with the adaptation pathway. Behavioral, microscopic, and mutational analyses, as well as mass spectrometry will be used to uncover the molecular basis for stimuli adaptation. Second, the role of CheT in chemotactic signaling will be elucidated through genetic, behavioral, phosphorylation, and structural analyses. The proposed research will advance knowledge of complex sensory systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

趋化性使能动的细菌能够远离有害的化学物质，向有益的化学物质移动。一个独特的运动土壤细菌群是根瘤菌，它可以与豆科植物如豌豆、大豆和苜蓿建立特定的共生关系。这种共生关系为宿主植物提供氮，氮是植物生长的最大限制性营养素。趋化性过程使根瘤菌能够识别并向其宿主移动，从而改善共生关系，从而促进植物生长。根瘤菌利用多种化学感受器蛋白来感受寄主植物分泌的多种化学物质。然而，很少有人知道的敏感性和适应性，这是一个有效的趋化反应的基本特征的调节所涉及的具体过程。这个项目的首要目标是解码控制刺激适应的途径。这些结果将改变我们目前对细菌趋化性及其与真核宿主相互作用的生物学概念。这项研究的结果可以通过潜在地减少人造肥料的使用，从而降低成本和减少污染的农业，直接有益于未来的农业和环境问题。更广泛的影响活动包括研究的内在价值，因为固氮是生物圈中最重要的过程之一。 此外，该项目将涉及研究生的跨学科培训。该团队致力于指导研究生和本科生，特别是代表性不足的人口和妇女。此外，还在校内和校外为中小学生进行了实际操作演示，并邀请大学生和高中生参与研究。模式植物苜蓿中华根瘤菌（Sinorhizobium meliloti）的趋化系统比肠道细菌的趋化系统更加复杂。虽然最近发现了一些独特的成分和功能控制趋化性，调节途径的敏感性和刺激适应是未知的。本研究项目的目的是阐明受体修饰系统，这在这一过程中起着关键作用。具体来说，一种新的趋化蛋白，CheT，这是前所未有的相互作用与适应途径的保守元素的功能，将被破译。首先，研究人员将描述控制适应的趋化途径。两个化学感受器在宿主植物传感，即氨基酸传感器McpU和甜菜碱传感器McpX的核心作用，将作为模型，因为它们预计将表现出不同的模式与适应途径的相互作用。行为，显微镜和突变分析，以及质谱将被用来揭示刺激适应的分子基础。其次，将通过遗传、行为、磷酸化和结构分析阐明CheT在趋化信号传导中的作用。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估来支持。