State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096, China.
Department of Bioinformatics, School of Biomedical Engineering and Informatics, Nanjing Medical University, Nanjing 211166, China.
Biomed Res Int. 2019 Nov 11;2019:6151587. doi: 10.1155/2019/6151587. eCollection 2019.
Microorganisms can transfer electrons directly to extracellular acceptors, during which organic compounds are oxidized to carbon dioxide. One of these microbes, Geobacter sulfurreducens, is well known for the "metallic-like" conductivity of its type IV pili. However, there is no consensus on what the mechanism for electron transfer along these conductive pili is. Based on the aromatic distances and orientations of our predicted models, the mechanism of electron transfer in the (GS) pili was explored by quantum chemical calculations with Marcus theory of electron transfer reactions. Three aromatic residues from the N-terminal -helix of the GS pilin subunit are packed together, resulting in a continuous pi-pi interaction chain. The theoretical conductance (4.69 S/3.85 S) of the predicted models is very similar to that in the experiments reported recently (3.40 S). These findings offer a new concept that the GS pili belongs to a new class of proteins that can transport electrons through pi-pi interaction between aromatic residues and also provide a valuable tool for guiding further researches of these conductive pili, to investigate their roles in biogeochemical cycling, and potential applications in biomaterials, bioelectronics, and bioenergy.
微生物可以直接将电子转移到细胞外受体，在此过程中有机化合物被氧化为二氧化碳。其中一种微生物，脱硫弧菌，以其四型菌毛的“金属样”导电性而闻名。然而，对于电子沿着这些导电菌毛的转移机制，还没有共识。基于我们预测模型的芳香族距离和取向，通过量子化学计算和电子转移反应的 Marcus 理论，探讨了 (GS) 菌毛中的电子转移机制。来自 GS 菌毛亚基 N 端 -螺旋的三个芳香族残基聚集在一起，形成了连续的 pi-pi 相互作用链。预测模型的理论电导率（4.69 S/3.85 S）与最近报道的实验结果（3.40 S）非常相似。这些发现提供了一个新概念，即 GS 菌毛属于一类新的蛋白质，可以通过芳香族残基之间的 pi-pi 相互作用来传递电子，也为进一步研究这些导电菌毛提供了有价值的工具，以研究它们在生物地球化学循环中的作用，以及在生物材料、生物电子学和生物能源中的潜在应用。
