Cryo-EM structure of native human uromodulin, a zona pellucida module polymer.

Assembly of extracellular filaments and matrices mediating fundamental biological processes such as morphogenesis, hearing, fertilization, and antibacterial defense is driven by a ubiquitous polymerization module known as zona pellucida (ZP) “domain”. Despite the conservation of this element from hydra to humans, no detailed information is available on the filamentous conformation of any ZP module protein. Here, we report a cryo‐electron microscopy study of uromodulin (UMOD)/Tamm–Horsfall protein, the most abundant protein in human urine and an archetypal ZP module‐containing molecule, in its mature homopolymeric state. UMOD forms a one‐start helix with an unprecedented 180‐degree twist between subunits enfolded by interdomain linkers that have completely reorganized as a result of propeptide dissociation. Lateral interaction between filaments in the urine generates sheets exposing a checkerboard of binding sites to capture uropathogenic bacteria, and UMOD‐based models of heteromeric vertebrate egg coat filaments identify a common sperm‐binding region at the interface between subunits. Insights into the architecture of uromodulin filaments involved in the capture of uropathogenic bacteria, and structurally‐related vertebrate egg coat material, suggest how a widespread extracellular polymerization module can support multiple functions.

细胞外细丝和基质的组装介导了诸如形态发生、听觉、受精和抗菌防御等基本生物学过程，这是由一种被称为透明带（ZP）“结构域”的普遍存在的聚合模块驱动的。尽管从水螅到人类这一元件都具有保守性，但关于任何ZP模块蛋白的丝状构象都没有详细信息。在此，我们报道了一项对尿调节素（UMOD）/塔姆 - 霍斯福尔蛋白的冷冻电子显微镜研究，该蛋白是人类尿液中含量最丰富的蛋白，也是一种含有ZP模块的典型分子，处于其成熟的同聚体状态。UMOD形成一种单链螺旋，亚基之间有前所未有的180度扭转，这些亚基被结构域间连接体包裹，由于前肽解离，连接体已完全重组。尿液中细丝之间的侧向相互作用产生薄片，暴露出一个棋盘状的结合位点以捕获尿路致病菌，并且基于UMOD的异聚体脊椎动物卵壳细丝模型在亚基之间的界面处确定了一个常见的精子结合区域。 对参与捕获尿路致病菌的尿调节素细丝结构以及与结构相关的脊椎动物卵壳物质的深入了解，揭示了一种广泛存在的细胞外聚合模块如何能够支持多种功能。