NSF-ANR: Cytochrome nanowires: secretion, assembly and function in ultrafast electron transfer by microbial biofilms

常见的土壤细菌硫还原地杆菌具有与合成聚合物相媲美的高电子导电性生物膜的显著能力。这种导电性使细菌能够通过数百个细胞长度将呼吸电子传输到远端的受体或伴侣细胞。这一过程对全球环境以及生物能源、生物燃料和生物电子学的应用至关重要。人们一直认为生物膜通过由IV型菌毛丝组成的微生物纳米线传递电子。PI最近解决了能够进行细胞外电子转移（EET）的生物体的菌毛的第一个结构。这些毛被认为可以解释纤维的导电性，但PI实验室的工作发现它们的导电性非常低，与它们的结构一致。这个项目的目的是破译纳米线分泌、组装和功能的物理基础。本项目将描述G.硫还原菌的分泌机制和这类新的两部分毛的作用。该项目将确定毛丝介导的细胞色素分泌的物理基础，确定其生物发生的所有必要因素，并开发工具来表征纳米线分泌的物理基础。该研究将为制造生物材料分泌所需的毛提供一个生物电子平台。该项目将培训不同背景的用户使用多功能生物材料，为培养下一代生物学、物理学、化学、数据科学和工程学交叉学科的科学家做好准备。本课题的主要目的是重建异源系统中硫还原G.菌毛的生物发生、组装和分泌途径，以解剖蛋白-蛋白相互作用。另一个目的是阐明异二聚体菌毛组装中菌毛动力学和机械稳定性的机制。目的包括通过量化OmcS/Z与毛毛的相互作用来确定其分泌机制，以及通过低温电子断层扫描表征新的基于毛毛地杆菌的细胞色素分泌系统的结构。这个美国/法国合作项目由美国国家科学基金会和法国国家研究机构支持，其中美国国家科学基金会资助美国研究者，法国国家研究机构资助法国合作伙伴。该奖项反映了美国国家科学基金会的法定使命，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。

Common soil bacterium Geobacter sulfurreducens has remarkable ability to form biofilms with high electronic conductivity rivalling those of synthetic polymers. This conductivity enables bacteria to transport respiratory electrons over hundreds of cell lengths to remote acceptors or partner cells. This process is critical for global environment and for applications in bioenergy, biofuels, and bioelectronics. It has been thought that biofilms transfer electrons via microbial nanowires made up of type IV pili filaments. The PI recently solved the first structure of a pilus from an organism capable of extracellular electron transfer (EET). These pili were thought to account for filament conductivity, but the work from the PI’s lab found that their conductivity is very low, in agreement with their structure. The aim of this project is to decipher the physical basis of nanowire secretion, assembly, and function. This project will characterize the G. sulfurreducens secretion machinery and the role of this novel class of bipartite pili. This project will identify the physical basis of pili -mediated cytochrome secretion and identify all factors essential for their biogenesis and develop tools to characterize the physical basis of nanowire secretion. This research will lead to a bioelectronic platform to manufacture pili required for the secretion of living biomaterials. This project will train users with different backgrounds in the use of multifunctional biomaterials to prepare the next generation of trans-disciplinary scientists trained at the interface of biology, physics, chemistry, data science and engineering.The primary aims of this project include reconstitution of G. sulfurreducens pili biogenesis, assembly, and secretion pathway in a heterologous system to dissect protein-protein interactions. Another aim is the elucidation of the mechanism of pilus dynamics and mechanical stability in the heterodimeric pilus assembly. The aims include determination of the mechanism of OmcS/Z secretion by quantifying how they interact with pili, and the characterization of the structure of the novel Geobacter pili-based cytochrome secretion system by cryo-electron tomography. This collaborative US/France project is supported by the US National Science Foundation and the French Agence Nationale de la Recherche, where NSF funds the US investigator and ANR funds the partners in France.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.