Ochner Hannah, Böhning Jan, Wang Zhexin, Tarafder Abul K, Caspy Ido, Bharat Tanmay A M
Structural Studies Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, United Kingdom.
PLoS Pathog. 2024 Dec 12;20(12):e1012773. doi: 10.1371/journal.ppat.1012773. eCollection 2024 Dec.
Type IV pili (T4Ps) are abundant in many bacterial and archaeal species, where they play important roles in both surface sensing and twitching motility, with implications for adhesion, biofilm formation and pathogenicity. While Type IV pilus (T4P) structures from other organisms have been previously solved, a high-resolution structure of the native, fully assembled T4P of Pseudomonas aeruginosa, a major human pathogen, would be valuable in a drug discovery context. Here, we report a 3.2 Å-resolution structure of the P. aeruginosa PAO1 T4P determined by electron cryomicroscopy (cryo-EM). PilA subunits constituting the T4P exhibit a classical pilin fold featuring an extended N-terminal α-helix linked to a C-terminal globular β-sheet-containing domain, which are packed tightly along the pilus, in line with models derived from previous cryo-EM data of the P. aeruginosa PAK strain. The N-terminal helices constitute the pilus core where they stabilise the tubular assembly via hydrophobic interactions. The α-helical core of the pilus is surrounded by the C-terminal globular domain of PilA that coats the outer surface of the pilus, mediating interactions with the surrounding environment. Comparison of the P. aeruginosa PAO1 T4P with T4P structures from other organisms, both at the level of the pilin subunits and the fully assembled pili, confirms previously described common architectural principles whilst highlighting key differences between members of this abundant class of prokaryotic filaments. This study provides a structural framework for understanding the molecular and cell biology of these important cellular appendages mediating interaction of prokaryotes to surfaces.
IV型菌毛（T4P）在许多细菌和古菌物种中大量存在，它们在表面感知和颤动运动中都发挥着重要作用，对粘附、生物膜形成和致病性有影响。虽然之前已经解析了来自其他生物体的IV型菌毛（T4P）结构，但对于主要人类病原体铜绿假单胞菌天然、完全组装的T4P的高分辨率结构，在药物发现背景下将具有重要价值。在此，我们报告了通过电子冷冻显微镜（cryo-EM）确定的铜绿假单胞菌PAO1 T4P的3.2 Å分辨率结构。构成T4P的PilA亚基呈现出经典的菌毛蛋白折叠，其特征是一个延伸的N端α螺旋与一个包含C端球状β片层的结构域相连，这些结构域沿着菌毛紧密堆积，这与从铜绿假单胞菌PAK菌株先前的冷冻电镜数据得出的模型一致。N端螺旋构成菌毛核心，它们通过疏水相互作用稳定管状组装。菌毛的α螺旋核心被PilA的C端球状结构域包围，该结构域覆盖菌毛的外表面，介导与周围环境的相互作用。将铜绿假单胞菌PAO1 T4P与来自其他生物体的T4P结构在菌毛蛋白亚基和完全组装的菌毛水平上进行比较，证实了先前描述的共同结构原则，同时突出了这类丰富的原核细丝成员之间的关键差异。这项研究为理解这些重要细胞附属物的分子和细胞生物学提供了一个结构框架，这些附属物介导原核生物与表面的相互作用。
