Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK.
Institute of Molecular Biology and Biophysics, Swiss Federal Institute of Technology Zurich, Otto-Stern-Weg 5, 8093 Zurich, Switzerland.
Structure. 2017 Dec 5;25(12):1829-1838.e4. doi: 10.1016/j.str.2017.10.004. Epub 2017 Nov 9.
Adhesive chaperone-usher pili are long, supramolecular protein fibers displayed on the surface of many bacterial pathogens. The type 1 and P pili of uropathogenic Escherichia coli (UPEC) play important roles during urinary tract colonization, mediating attachment to the bladder and kidney, respectively. The biomechanical properties of the helical pilus rods allow them to reversibly uncoil in response to flow-induced forces, allowing UPEC to retain a foothold in the unique and hostile environment of the urinary tract. Here we provide the 4.2-Å resolution cryo-EM structure of the type 1 pilus rod, which together with the previous P pilus rod structure rationalizes the remarkable "spring-like" properties of chaperone-usher pili. The cryo-EM structure of the type 1 pilus rod differs in its helical parameters from the structure determined previously by a hybrid approach. We provide evidence that these structural differences originate from different quaternary structures of pili assembled in vivo and in vitro.
黏附伴侣菌毛是一种长的、超分子蛋白质纤维，存在于许多细菌病原体的表面。尿路致病性大肠杆菌（UPEC）的 I 型菌毛和 P 菌毛在尿路定植过程中发挥重要作用，分别介导与膀胱和肾脏的黏附。螺旋菌毛杆的生物力学特性允许它们对流动诱导的力进行可逆解旋，使 UPEC 在尿路这一独特而恶劣的环境中得以立足。在这里，我们提供了 4.2 Å 分辨率的 I 型菌毛杆的冷冻电镜结构，该结构与之前的 P 菌毛杆结构一起，合理地解释了伴侣菌毛的显著“弹簧样”特性。I 型菌毛杆的冷冻电镜结构在螺旋参数上与之前通过混合方法确定的结构不同。我们提供的证据表明，这些结构差异源于体内和体外组装的菌毛的不同四级结构。
