Specificity of chemotaxis-driven motility in Sinorhizobium meliloti host interaction

苜蓿中华根瘤菌宿主相互作用中趋化驱动运动的特异性

• 批准号: 1817652
• 负责人: Birgit Scharf
• 金额: $ 99.12万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-01 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1817652&HistoricalAwards=false
• 关键词: Specificity; chemotaxis; driven; motility; 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 live freely in the soil, as well as 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 in the model rhizobium Sinorhizobium meliloti allows the organism to recognize its host, which improves the symbiotic relationship, and consequently, enhances plant growth. The PI discovered multiple and diverse chemoreceptors in S. meliloti, which are used to sense chemical compounds. However, little is known about the attractant spectrum or the specificity of rhizobial chemoreceptors. The overarching goal of this project is to characterize the specific adaptations of S. meliloti chemoreception to the range of host-derived attractants. Results from this research will transform our current concepts of bacterial behavior in soil through discovery of emergent properties of legume-rhizobia interactions. Chemotaxis of the soil bacterium Sinorhizobium meliloti is a critical prerequisite for the establishment of its symbiotic relationship with alfalfa. The discovery of a new type of bacterial chemotaxis, namely attraction to plant-borne betaines, and the identification of the rhizobial chemoreceptor for these compounds expands our understanding of plant-bacteria communication. The results of this research will open avenues for developing novel and innovative strategies to enhance chemoreception in the symbiotic bacterium S. meliloti, which will increase symbiotic efficiency, result in higher level of nitrogen fixation, and may ultimately increase crop yields. This project can directly benefit future agricultural and environmental issues by reducing the use of chemical fertilizers. Broader Impacts activities will involve the interdisciplinary training of graduate students. The team is committed to mentoring graduate and undergraduate students, especially underrepresented minorities and women. Public outreach activities include hands-on demonstrations for elementary and high school students, both on- and off-campus, and involvement of high school students in research.Using the Alfalfa-S. meliloti interaction as a model system, the investigators aim to elucidate the molecular mechanisms that govern legume-rhizobia communications. Understanding these mechanisms could open important new avenues for addressing daunting agricultural and environmental issues. This research will characterize S. meliloti chemoreceptors for which functional understanding is lacking. In an orthogonal approach, the investigators will define the nature of plant-derived compounds responsible for the recruitment of S. meliloti to the host rhizosphere. The composition of compounds exuded by plants into the rhizosphere has specifically evolved to attract symbiotic microbes to the roots of their corresponding hosts. First, the investigators propose to characterize the diverse phytochemicals secreted by the S. meliloti host alfalfa using mass-spectrometric metabolome analysis and quantitative chemotaxis assays. This study will uncover the S. meliloti attractome and establish the contributions of individual compounds to chemotaxis. Second, they propose to identify receptor ligands for individual chemoreceptors and determine receptor-ligand interaction through behavioral, genetic, biochemical, and structural analyses. The already highly advanced biochemical and structural characterization of McpX serves as blueprint for these analyses. The proposed research will advance our knowledge of the role of exuded root metabolites in the dialogue between plants and microbes.The Project is jointly funded by Molecular and Cellular Biosciences (CDF Cluster) and Integrative Organismal Systems (PBI Cluster), with additional support provided by the Directorate's Rule of Life Venture Fund.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。根瘤菌是一类独特的能动土壤细菌，它可以自由地生活在土壤中，并与豆科植物如豌豆、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。苜蓿中华根瘤菌（Sinorhizobium meliloti）的趋化过程允许生物体识别其宿主，这改善了共生关系，从而促进植物生长。PI在S.草木樨，用来感知化合物。然而，关于根瘤菌化学受体的引诱物谱或特异性知之甚少。该项目的总体目标是描述S.草蛉化学感受性的寄主衍生的引诱剂的范围。这项研究的结果将通过发现豆科植物-根瘤菌相互作用的紧急特性来改变我们目前对土壤中细菌行为的概念。土壤细菌苜蓿中华根瘤菌的趋化性是其与苜蓿建立共生关系的重要前提。一种新型细菌趋化性的发现，即吸引植物产生的甜菜碱，以及这些化合物的根瘤菌化学受体的鉴定扩展了我们对植物-细菌通信的理解。这项研究的结果将为开发新的和创新的策略开辟道路，以增强共生细菌S。草木樨，这将提高共生效率，导致更高水平的固氮，并可能最终提高作物产量。该项目可以通过减少化肥的使用，直接有利于未来的农业和环境问题。更广泛的影响活动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少数民族和妇女。公共推广活动包括为小学生和高中生进行校内和校外的动手示范，以及高中生参与研究。苜蓿互作作为一个模型系统，研究人员的目标是阐明管理豆科植物根瘤菌通信的分子机制。了解这些机制可以为解决令人生畏的农业和环境问题开辟重要的新途径。本研究将对S.苜蓿化学感受器的功能缺乏了解。在一个正交的方法中，研究人员将定义负责招募S的植物衍生化合物的性质。苜蓿草木樨对寄主根际的影响。植物分泌到根际的化合物的组成已经特别进化，以吸引共生微生物到其相应宿主的根部。首先，研究者们提出了描述S.利用质谱代谢组学分析和定量趋化性测定对苜蓿草木樨宿主苜蓿进行了研究。本研究将揭示S.草木犀吸引体，并建立单个化合物的趋化性的贡献。第二，他们建议通过行为、遗传、生化和结构分析来鉴定个体化学感受器的受体配体并确定受体-配体相互作用。McpX已经非常先进的生化和结构表征作为这些分析的蓝图。这项研究将进一步加深我们对根系分泌物在植物与微生物对话中的作用的认识。该项目由分子和细胞生物科学公司共同资助（CDF集群）和集成有机系统（所涉方案预算问题组群），该奖项反映了NSF的法定使命，并通过使用基金会的学术价值和更广泛的影响审查标准。

项目成果

Sinorhizobium meliloti Chemoreceptor McpV Senses Short-Chain Carboxylates via Direct Binding

• DOI: 10.1128/jb.00519-18
• 发表时间: 2018-12-01
• 期刊: JOURNAL OF BACTERIOLOGY
• 影响因子: 3.2
• 作者: Compton, K. Karl;Hildreth, Sherry B.;Scharf, Birgit E.
• 通讯作者: Scharf, Birgit E.

Cellular Stoichiometry of Chemotaxis Proteins in Sinorhizobium meliloti

• DOI: 10.1128/jb.00141-20
• 发表时间: 2020-07-01
• 期刊: JOURNAL OF BACTERIOLOGY
• 影响因子: 3.2
• 作者: Arapov, Timofey D.;Saldana, Rafael Castanda;Scharf, Birgit E.
• 通讯作者: Scharf, Birgit E.

Formation of phage lysis patterns and implications on co-propagation of phages and motile host bacteria

• DOI: 10.1371/journal.pcbi.1007236
• 发表时间: 2020-03-01
• 期刊: PLOS COMPUTATIONAL BIOLOGY
• 影响因子: 4.3
• 作者: Li, Xiaochu;Gonzalez, Floricel;Chen, Jing
• 通讯作者: Chen, Jing

McpT, a Broad-Range Carboxylate Chemoreceptor in Sinorhizobium meliloti

• DOI: 10.1128/jb.00216-21
• 发表时间: 2021-09-01
• 期刊: JOURNAL OF BACTERIOLOGY
• 影响因子: 3.2
• 作者: Baaziz, Hiba;Compton, K. Karl;Scharf, Birgit E.
• 通讯作者: Scharf, Birgit E.