Corsetti Fabiano, Alonso-Caballero Alvaro, Poly Simon, Perez-Jimenez Raul, Artacho Emilio
Department of Materials, Imperial College London, London SW7 2AZ, UK.
Department of Physics, Imperial College London, London SW7 2AZ, UK.
R Soc Open Sci. 2020 Apr 15;7(4):200183. doi: 10.1098/rsos.200183. eCollection 2020 Apr.
The type 1 pilus is a bacterial filament consisting of a long coiled proteic chain of subunits joined together by non-covalent bonding between complementing -strands. Its strength and structural stability are critical for its anchoring function in uropathogenic bacteria. The pulling and unravelling of the FimG subunit of the pilus was recently studied by atomic force microscopy experiments and steered molecular dynamics simulations (Alonso-Caballero 2018 . , 2758. (doi:10.1038/s41467-018-05107-6)). In this work, we perform a quantitative comparison between experiment and simulation, showing a good agreement in the underlying work values for the unfolding. The simulation results are then used to estimate the free energy difference for the detachment of FimG from the complementing strand of the neighbouring subunit in the chain, FimF. Finally, we show that the large free energy difference for the unravelling and detachment of the subunits which leads to the high stability of the chain is entirely entropic in nature.
1型菌毛是一种细菌细丝，由一条长的盘绕蛋白质链组成，该链由亚基通过互补β链之间的非共价键连接在一起。其强度和结构稳定性对于其在尿路致病性细菌中的锚定功能至关重要。最近通过原子力显微镜实验和引导分子动力学模拟研究了菌毛FimG亚基的拉伸和解开（阿隆索 - 卡瓦列罗，2018年。，2758。（doi：10.1038/s41467-018-05107-6））。在这项工作中，我们对实验和模拟进行了定量比较，结果表明在解折叠的基础功值方面具有良好的一致性。然后，模拟结果用于估计FimG从链中相邻亚基FimF的互补链上脱离的自由能差。最后，我们表明，亚基解折叠和脱离的大自由能差导致链的高稳定性，其本质上完全是熵的。
