Hvorecny Kelli L, Interlandi Gianluca, Veth Tim S, Aprikian Pavel, Manchenko Anna, Tchesnokova Veronika L, Dickinson Miles S, Quispe Joel D, Riley Nicholas M, Klevit Rachel E, Magala Pearl, Sokurenko Evgeni V, Kollman Justin M
Department of Biochemistry, University of Washington, Seattle, WA.
Department of Bioengineering, University of Washington, Seattle, WA.
bioRxiv. 2024 Dec 14:2024.12.06.627246. doi: 10.1101/2024.12.06.627246.
A critical step in infections is the attachment of many microorganisms to host cells using lectins that bind surface glycans, making lectins promising antimicrobial targets. Upon binding mannosylated glycans, FimH, the most studied lectin adhesin of type 1 fimbriae in , undergoes an allosteric transition from an inactive to an active conformation that can act as a catch-bond. Monoclonal antibodies that alter FimH glycan binding in various ways are available, but the mechanisms of these antibodies remain unclear. Here, we use cryoEM, mass spectrometry, binding assays, and molecular dynamics simulations to determine the structure-function relationships underlying antibody-FimH binding. Our study reveals four distinct antibody mechanisms of action: ligand mimicry by an N-linked, high-mannose glycan; stabilization of the ligand pocket in the inactive state; conformational trapping of the active and inactive states; and locking of the ligand pocket through long-range allosteric effects. These structures reveal multiple mechanisms of antibody responses to an allosteric protein and provide blueprints for new antimicrobial that target adhesins.
感染过程中的一个关键步骤是许多微生物利用结合表面聚糖的凝集素附着于宿主细胞，这使得凝集素成为有前景的抗菌靶点。在结合甘露糖基化聚糖后，FimH（大肠杆菌中研究最多的1型菌毛凝集素粘附素）会经历从无活性构象到活性构象的变构转变，该活性构象可作为一种捕获键。有以各种方式改变FimH聚糖结合的单克隆抗体，但这些抗体的作用机制仍不清楚。在这里，我们使用冷冻电镜、质谱、结合测定和分子动力学模拟来确定抗体与FimH结合的结构 - 功能关系。我们的研究揭示了四种不同的抗体作用机制：由N - 连接的高甘露糖聚糖进行配体模拟；在无活性状态下稳定配体口袋；对活性和无活性状态进行构象捕获；以及通过远程变构效应锁定配体口袋。这些结构揭示了抗体对变构蛋白反应的多种机制，并为靶向粘附素的新型抗菌剂提供了蓝图。
