Laboratory of Structural Neurobiology, Department of Cellular and Molecular Medicine, Faculty of Medicine, KU Leuven, Leuven, Belgium.
Laboratory for the Structure and Function of Biological Membranes, Center for Structural Biology and Bioinformatics, Université libre de Bruxelles, Brussels, Belgium.
Elife. 2020 Jan 28;9:e51511. doi: 10.7554/eLife.51511.
Pentameric ligand-gated ion channels (pLGICs) or Cys-loop receptors are involved in fast synaptic signaling in the nervous system. Allosteric modulators bind to sites that are remote from the neurotransmitter binding site, but modify coupling of ligand binding to channel opening. In this study, we developed nanobodies (single domain antibodies), which are functionally active as allosteric modulators, and solved co-crystal structures of the prokaryote () channel ELIC bound either to a positive or a negative allosteric modulator. The allosteric nanobody binding sites partially overlap with those of small molecule modulators, including a vestibule binding site that is not accessible in some pLGICs. Using mutagenesis, we extrapolate the functional importance of the vestibule binding site to the human 5-HT receptor, suggesting a common mechanism of modulation in this protein and ELIC. Thus we identify key elements of allosteric binding sites, and extend drug design possibilities in pLGICs with an accessible vestibule site.
五聚体配体门控离子通道（pLGICs）或 Cys 环受体参与神经系统中的快速突触信号传递。变构调节剂结合在远离神经递质结合位点的部位，但可改变配体结合与通道开放的偶联。在这项研究中，我们开发了纳米抗体（单域抗体），它们作为变构调节剂具有功能活性，并解析了与正或负变构调节剂结合的原核（）通道 ELIC 的共晶结构。变构纳米抗体结合位点与小分子调节剂的结合位点部分重叠，包括一个前庭结合位点，在一些 pLGICs 中不可用。通过突变，我们推断前庭结合位点在人类 5-HT 受体中的功能重要性，这表明该蛋白和 ELIC 的调节存在共同机制。因此，我们确定了变构结合位点的关键要素，并通过具有可及前庭位点的 pLGIC 扩展了药物设计的可能性。
