Molecular Mechanisms Underlying Insect Odorant Receptor Function and Modulation

项目摘要 昆虫是许多致命疾病的主要传播媒介。蚊子和其他叮咬昆虫依靠它们的 敏锐的嗅觉来识别并锁定人类宿主因此，一种控制 昆虫传播疾病的传播是针对昆虫嗅觉受体，破坏最初的检测， 人类挥发物，并防止昆虫找到人类。开发有效的驱虫剂的目标是， 昆虫嗅觉受体的独特分子性质极大地促进了跛足寄主寻找行为。 昆虫嗅觉受体是一类新型的异聚体离子通道，由两个不同的亚基组成： 赋予气味特异性的高度不同的气味受体（OR）亚基和共同的Orco亚基， 这在不同的昆虫物种中实际上是不变的，反映了其在嗅觉传导中的重要作用。 鉴于Orco在气味检测中的保守和关键作用，它形成了一个理想的分子靶标， 急需的新一代驱虫剂，有可能阻止虫媒病毒的传播。 疾病不幸的是，由于这些受体代表了昆虫的独特专业化，并且缺乏结构性， 与任何其他离子通道家族同源，它们的许多最基本的结构和功能特性 仍然难以捉摸，排除了足够的机械理解，以指导驱蚊剂的设计。填补这一 在该领域的重要空白，我的实验室最近确定了一个奥科同源通道的结构，使用低温， 电子显微镜，提供了昆虫嗅觉受体的第一个结构快照。在此基础上 先进和我们的专业知识，气味受体生物化学，我们建议阐明结构的Orco在 复制其天然环境的条件：包埋在脂质膜内（Aim 1）并组装 与OR形成异聚体通道（Aim 2），单独使用以及与合成激动剂和增味剂复合使用。 揭示昆虫嗅觉受体在载脂蛋白和配体结合状态下的多种结构，将提供 直接洞察其变构调节的结构和机制基础。在一起，拟议的 研究提供了一个独特的和强大的进展，以合理设计的小分子驱虫剂，破坏气味 人类疾病的昆虫媒介的检测和宿主寻找行为。

Project Summary Insects are the primary vectors for many deadly diseases. Mosquitoes and other biting insects rely on their exquisite sense of smell to identify and hone in on their human hosts. Consequently, one strategy to control the transmission of insect-borne diseases is to target insect olfactory receptors, disrupt the initial detection of human volatiles, and prevent insects from locating humans. The goal of developing potent insect repellents that cripple host-seeking behavior is greatly facilitated by the unique molecular nature of insect olfactory receptors. Insect olfactory receptors form a novel class of heteromeric ion channels comprised of two distinct subunits—a highly divergent odorant receptor (OR) subunit that confers odorant specificity and a common Orco subunit, that is virtually invariant amongst diverse insect species, reflecting its essential role in olfactory transduction. Given the conserved and critical role that Orco plays in odor detection, it forms an ideal molecular target for a much-needed new generation of insect repellents with the potential to halt the transmission of insect-borne diseases. Unfortunately, as these receptors represent a unique specialization of insects and lack structural homology to any other ion channel family, many of their most elementary structural and functional properties have remained elusive, precluding sufficient mechanistic understanding to guide repellent design. To fill this important void in the field, my lab recently determined the structure of an Orco homomeric channel using cryo- electron microscopy, providing the first structural snapshot of an insect olfactory receptor. Building on this advance and our expertise in odorant receptor biochemistry, we propose to elucidate the structure of Orco in conditions that replicate its native environment: embedded within a lipid membrane (Aim 1) and assembled with an OR to form a heteromeric channel (Aim 2), alone and in complex with synthetic agonists and odorants. Revealing multiple structures of insect olfactory receptors in both apo and ligand bound states will provide direct insight into the structural and mechanistic basis for their allosteric modulation. Together, the proposed studies offer a unique and powerful inroad to the rational design of small-molecule repellents that disrupt odor detection and host-seeking behavior in insect vectors of human disease.