Department of Physics, Umeå University, Umeå, Sweden.
Department of Chemistry, The College of New Jersey, Ewing, New Jersey.
Biophys J. 2022 Jun 7;121(11):2096-2106. doi: 10.1016/j.bpj.2022.04.036. Epub 2022 Apr 30.
Adhesion pili assembled by the chaperone-usher pathway are superelastic helical filaments on the surface of bacteria, optimized for attachment to target cells. Here, we investigate the biophysical function and structural interactions that stabilize P pili from uropathogenic bacteria. Using optical tweezers, we measure P pilus subunit-subunit interaction dynamics and show that pilus compliance is contour-length dependent. Atomic details of subunit-subunit interactions of pili under tension are shown using steered molecular dynamics (sMD) simulations. sMD results also indicate that the N-terminal "staple" region of P pili, which provides interactions with pilins that are four and five subunits away, significantly stabilizes the helical filament structure. These data are consistent with previous structural data, and suggest that more layer-to-layer interactions could compensate for the lack of a staple in type 1 pili. This study informs our understanding of essential structural and dynamic features of adhesion pili, supporting the hypothesis that the function of pili is critically dependent on their structure and biophysical properties.
菌毛由伴侣蛋白- usher 通路组装而成，是细菌表面的超弹性螺旋丝，最适合与靶细胞结合。在这里，我们研究了稳定尿路致病性细菌 P 菌毛的生物物理功能和结构相互作用。我们使用光学镊子测量了 P 菌毛亚基-亚基相互作用的动力学，并表明菌毛顺应性与轮廓长度有关。使用导向分子动力学 (sMD) 模拟显示了张力下菌毛亚基-亚基相互作用的原子细节。sMD 结果还表明，P 菌毛的 N 端“订书钉”区域为与相隔四个和五个亚基的菌毛相互作用提供了基础，显著稳定了螺旋丝结构。这些数据与之前的结构数据一致，并表明更多的层-层相互作用可以弥补 1 型菌毛中订书钉的缺失。这项研究为我们了解粘附菌毛的基本结构和动态特征提供了信息，支持了菌毛的功能与其结构和生物物理特性密切相关的假说。
