Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE 68588, USA.
Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA.
Structure. 2024 Nov 7;32(11):1936-1951.e5. doi: 10.1016/j.str.2024.09.015. Epub 2024 Oct 8.
Clostridium perfringens enterotoxin (CpE) causes prevalent and deadly gastrointestinal disorders. CpE binds to receptors called claudins on the apical surfaces of small intestinal epithelium. Claudins normally regulate paracellular transport but are hijacked from doing so by CpE and are instead led to form claudin/CpE complexes. Claudin/CpE complexes are the building blocks of oligomeric β-barrel pores that penetrate the plasma membrane and induce gut cytotoxicity. Here, we present the structures of CpE in complex with its native claudin receptor in humans, claudin-4, using cryogenic electron microscopy. The structures reveal the architecture of the claudin/CpE complex, the residues used in binding, the orientation of CpE relative to the membrane, and CpE-induced changes to claudin-4. Further, structures and modeling allude to the biophysical procession from claudin/CpE complexes to cytotoxic β-barrel pores during pathogenesis. In full, this work proposes a model of claudin/CpE assembly and provides strategies to obstruct its formation to treat CpE diseases.
产气荚膜梭菌肠毒素（CpE）可引起普遍存在且致命的胃肠道疾病。CpE 与小肠上皮细胞顶表面的称为紧密连接蛋白的受体结合。紧密连接蛋白通常调节细胞旁转运，但会被 CpE 劫持而无法发挥作用，相反，它们被引导形成紧密连接蛋白/CpE 复合物。紧密连接蛋白/CpE 复合物是穿透质膜并诱导肠道细胞毒性的寡聚 β-桶孔的构建块。在这里，我们使用低温电子显微镜呈现了 CpE 与其天然紧密连接蛋白受体在人类中的 Claudin-4 的复合物结构。这些结构揭示了紧密连接蛋白/CpE 复合物的结构、结合中使用的残基、CpE 相对于膜的取向以及 CpE 引起的 Claudin-4 变化。此外，结构和建模暗示了在发病机制过程中，从紧密连接蛋白/CpE 复合物到细胞毒性 β-桶孔的生物物理过程。总之，这项工作提出了紧密连接蛋白/CpE 组装的模型，并提供了阻止其形成以治疗 CpE 疾病的策略。
