Structural dynamics and function of the glutamate receptor ligand-binding domain

描述(申请人提供)：配基门控离子通道介导突触的信息传递。神经递质分子与这些通道的配体结合域(LBD)的结合推动跨膜孔的打开，允许阳离子流经细胞膜，触发突触后神经元产生神经冲动。激动剂结合的部位通常远离跨膜孔，因此通道的激活必须通过结合部位的构象变化与通道门处的相应变化的变构耦合来介导。离子型谷氨酸受体离子通道(IGluRs)介导脑和脊髓中绝大多数突触的兴奋性反应。越来越多的证据表明，iGluRs在多种神经退行性疾病和精神疾病中发挥着关键作用，这使它们成为治疗干预的重要靶点。IGluRs分为四个主要家族，AMPA、海人藻酸、NMDA和Delta受体。这些受体以四聚体的形式组装。LBD的现有晶体结构提供了非常丰富的信息，但它们只能提供系统最稳定构象状态的静态视图。我们设计了一项联合计算和实验研究，以扩大我们对负责iGluR调控的原子和分子因素的了解。我们将(1)使用自由能计算和实验测量来表征一组配体与AMPA、海人藻酸和NMDA受体LBD的配体结合过程，(2)使用自由能计算来表征作为AMPA、海人酸和NMDA受体脱敏基础的LBD-LBD二聚体重排，(3)测量LBD单体、系留二聚体和交联四聚体的溶液X射线散射，以与预测的构象群体进行比较，以及(4)尝试结晶交联稳定的LBD四聚体和稳定的LBD-孔组装。 与公共健康相关：我们提出了一个研究项目，旨在了解调节被称为谷氨酸受体的“神经受体”蛋白质的原子和分子因素。这些蛋白质在神经退行性疾病和精神疾病中起着关键作用。这项研究将有助于更好地理解针对谷氨酸受体的药物的作用。

DESCRIPTION (provided by applicant): Ligand-gated ion channels mediate information transfer at synapses. The binding of neurotransmitter molecules to the ligand-binding domains (LBDs) of these channels drive the opening of transmembrane pores, allowing cations to flow across the cell membrane to trigger the generation of a nerve impulse in the postsynaptic neuron. The site of agonist binding is usually distant from the transmembrane pore, so activation of the channel must be mediated by allosteric coupling of conformational changes at the binding site to corresponding changes at the channel's gate. The ionotropic glutamate receptor ion channels (iGluRs) mediate excitatory responses at the vast majority of synapses in the brain and spinal cord. A growing body of evidence indicates that iGluRs have key roles in a broad variety of neurodegenerative and psychiatric diseases, which makes them important targets for therapeutic intervention. iGluRs are divided into four major families, the AMPA, kainate, NMDA, and delta receptors. These receptors assemble as tetramers. The available crystal structures of the LBDs are very informative, but they can only provide a static view of the most stable conformational state of the system. We have designed a joint computational and experimental study to extend our knowledge of the atomic and molecular factors responsible for iGluR regulation. We will (1) characterize the process of ligand-binding for a set of ligands to the AMPA, kainate, and NMDA receptor LBDs using free energy computations and experimental measurements, (2) characterize LBD-LBD dimer rearrangements that underlie desensitization for the AMPA, kainate, and NMDA receptors using free energy computations, (3) measure solution X-ray scattering from LBD monomers, tethered dimers, and crosslinked tetramers to compare with the predicted conformational populations, and (4) try to crystallize crosslink-stabilized LBD tetramers and a stabilized LBD-pore assembly. PUBLIC HEALTH RELEVANCE: We propose a research project to understand the atomic and molecular factors that regulate "neuroreceptor" proteins called glutamate receptors. These proteins have key roles in neurodegenerative and psychiatric diseases. The research will help better understand the action of drugs targeting glutamate receptors.