铁还原菌关键细胞色素蛋白-铁氧化物矿物界面相互作用的分子机制及其环境意义

微生物-矿物相互作用是地表环境中重要的生物地球化学过程。细胞色素蛋白是铁还原菌跨膜电子传递链的重要组成部分，能够介导胞内物质和胞外矿物之间的电子传递。位于传递链终端的外膜细胞色素蛋白与矿物之间的相互作用会显著影响矿物-微生物界面电子传递效率。本项目拟研究模式铁还原菌Shewanella oneidensis MR-1外膜细胞色素蛋白MtrC和OmcA在不同铁氧化物矿物表面的结合位点、相互作用力以及吸附模型；结合原位表征技术和电化学分析技术揭示蛋白质在矿物表面吸附过程中结构的动态变化、及其相应电子传导能力的变化；利用原位液相透射电镜、电化学分析等方法研究蛋白质覆盖层对于铁氧化物矿物表面性质、团聚状态及其反应活性的影响。项目将从界面过程、蛋白质构效关系、以及矿物性质的变化三个方面，细致刻画矿物-细胞色素蛋白相互作用的微观过程，为认识微生物-矿物界面电子传递机制及其环境意义提供理论依。

Mineral-microbe interaction is an important biogeochemical process. Iron-reducing bacteria use a series of cytochromes to form a transmembrane electron transfer pathway that can transfer electrons from intracellular redox-active matters to extracellular minerals. The outer-membrane cytochromes at the end of the electron transfer pathway directly contact with mineral surface, so the interactions between outer-membrane cytochromes and mineral surface significantly impact the interfacial electron transfer between mineral-microbe. This proposed project will study the binding sites, interaction forces, and adsorption model of the outer-membrane cytochromes, MtrC and OmcA, of Shewanella oneidensis MR-1 on the surface of iron oxide minerals with varied surface properties. Flow-cell attenuated total reflection-Fourier transform infrared (ATR-FTIR) and protein film voltammetry will be used to study the conformational change of cytochromes upon adsorption onto mineral surface, as well as the difference in electron transfer capability of the cytochromes with the change of protein structure. Liquid cell transmission electron microscopy (LCTEM) and characterization of surface properties will be utilized to investigate the effects of the sorbed cytochromes on the aggregation behavior, surface properties, and bioavailability of iron oxide particles. The object of this study is to reveal the mineral-cytochrome interactions from the perspectives of minerals, proteins, and interfacial processes, which will provide important insights into the molecular mechanisms and environmental implications of electron transfer at the mineral-microbe interface.