Unraveling biofilm matrix composition, architecture, and function

正如我们所知，细菌对生命至关重要，它们在令人惊讶的环境中定居和繁衍，从人类宿主到黄石公园和工业石油管道中的酸性微生物垫。细菌形成称为生物膜的多细胞群落的倾向远远超过在悬浮液中持续存在的倾向。细菌分泌分子聚合物并将其包围，作为建筑材料，以粘液状组装体来缠绕和保护常驻细菌。PI最近的工作揭示了围绕E的非凡机械坚固的篮子状结构的组装。大肠杆菌细胞的生物膜，并导致发现了一种新的化学结构，以前从未观察到在自然界中的这些篮子。纤维素是地球上最丰富的生物聚合物，存在于植物和树木的细胞壁中，导致木材，纸张和棉花产品。其他行业也采用方法通过合成路线对标准纤维素进行改性以获得所需的性能，并用作食品添加剂以及膜和生物技术应用。E.大肠杆菌通过新定义的分子机制产生其自身独特的具有磷酸乙醇胺基团的纤维素修饰形式。该项目解决了涉及天然磷酸乙醇胺（pEtN）纤维素的关键问题：其改性图案，其物理性质和在新工业材料中的应用潜力，以及完整多糖-蛋白质纳米复合材料结构组装的分子基础。该项目将为细菌生理学、糖生物学和工业应用（包括新材料的生产和可再生能源的使用）提供新的研究方向。PI通过针对广大受众的科学和教育研究文章传达科学概念和发现。该项目将培训本科生和研究生，特别是那些来自STEM代表性不足的群体的学生。PI正在设计课程变化，将更多的定量概念和基于实践课程的本科研究经验（CURES）引入本科化学课程。该项目将整合生化分析与聚合物强度和材料特性的表征，电子显微镜，荧光显微镜，固态NMR光谱和质谱，以：（1）提供对两性离子磷酸乙醇胺纤维素的分子模式和物理性质的基本理解;（2）确定纤维素改性对细菌细胞表面卷曲的Velcro样缔合的影响;（3）定义对应于原位天然细菌复合物和体外形成的高度调谐复合物中curli和pEtN纤维素之间的分子相互作用的原子水平参数。除了揭示生物膜基质组装体的基本化学原理外，这项工作还将引入生产pEtN纤维素和同位素标记基质材料的新方法，并提供对传统方法分析构成挑战的不溶性基质材料的前所未有的原子级分析。该项目可能有助于揭示一种新的范式，用于理解其他淀粉样蛋白-多糖相互作用的分子基础，不仅在微生物中而且在真核细胞系统中普遍存在，并且应该激发对交替修饰的纤维素和多糖的搜索。该项目由生物科学理事会分子和细胞生物科学部的分子生物物理学小组支持。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Bacteria are essential to life as we know it and colonize and thrive in astonishing environments, ranging from within the human host to the acidic microbial mats in Yellowstone and industrial oil pipelines. The propensity for bacteria to form multicellular communities termed biofilms far exceeds the tendency to persist in suspension. Bacteria secrete and surround themselves with molecular polymers as building materials to enmesh and protect resident bacteria in slime-like assemblies. The PI’s recent work revealed the assembly of extraordinary mechanically robust basket-like architectures surrounding E. coli cells in biofilms and led to the discovery of a new chemical structure never before observed in nature within these baskets. Cellulose is the most abundant biopolymer on Earth, present in the cell walls of plants and trees, leading to wood, paper, and cotton products. Other industries also employ methods to modify standard cellulose through synthetic routes for desirable properties and are used as food additives and in membrane and biotechnology applications. E. coli produces its own uniquely modified form of cellulose with phosphoethanolamine groups through newly defined molecular machinery. This project tackles crucial questions involving nature’s phosphoethanolamine (pEtN) cellulose: its modification patterning, its physical properties and potential for application in new industrial materials, and the molecular basis for the assembly of the full polysaccharide-protein nanocomposite structures. This project will fuel new research directions with implications for bacterial physiology; glycobiology; and industrial applications including the production of new materials and uses in renewable energy. The PI communicates scientific concepts and discoveries through scientific and educational research articles targeted to broad audiences. This project will train undergraduate and graduate students, particularly those from groups under-represented in STEM. The PI is designing coursework changes to introduce more quantitative concepts and hands-on course-based undergraduate research experiences (CUREs) into undergraduate chemistry courses.This project will integrate biochemical analysis with characterization of polymer strength and materials properties, electron microscopy, fluorescence microscopy, solid-state NMR spectroscopy and mass spectrometry to: (1) deliver a fundamental understanding of the molecular patterning and physical properties of the zwitterionic phosphoethanolamine cellulose; (2) determine the influence of the cellulose modification on the Velcro-like association of curli at the bacterial cell surface; (3) define atomic-level parameters corresponding to molecular interactions between curli and pEtN cellulose in native bacterial composites in situ and highly tuned complexes formed in vitro. In addition to revealing the fundamental chemical principles underlying biofilm matrix assemblies, the work will introduce new methods for the production of pEtN cellulose and isotopically labeled matrix materials, and provide unprecedented atomic- level analysis of insoluble matrix materials that pose a challenge to analysis by conventional methods. The project may serve to reveal a new paradigm for understanding the molecular basis of other amyloid- polysaccharide interactions, prevalent not only in microorganisms but also in eukaryotic cell systems and should inspire the search for alternately modified celluloses and polysaccharides. This project is supported by the Molecular Biophysics Cluster of the Molecular and Cellular Biosciences Division in the Directorate for Biological Sciences.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.