Molecular Mechanisms Underlying Insect Odorant Receptor Function and Modulation

描述(申请人提供)：昆虫是许多致命疾病的主要媒介。蚊子和其他食血昆虫通过挥发性的嗅觉线索被它们的人类宿主吸引。因此，通过以昆虫气味受体为靶点，干扰最初的 检测人类挥发物，并防止蚊子和其他媒介定位其人类宿主。昆虫气味受体被认为形成了一类新的异构体离子通道，由两个不同的亚基组成--一个高度分化的气味受体(OR)亚基赋予气味特异性，另一个共同的Orco亚基在不同的昆虫物种中几乎是不变的，反映了在嗅觉转导中绝对重要的作用。不幸的是，由于这些受体缺乏任何结构上的同源物，它们的许多最基本的结构和功能特性仍然难以捉摸，这排除了足够的机制理解来指导药物设计。这项提议的目的是为昆虫气味受体带来急需的分子洞察力。我们计划对Orco进行单独和与先前发现的小分子激动剂和拮抗剂复合的X射线结晶学研究，作为一种策略，以揭示这一关键嗅觉通道中调制的结构和机制基础。同时，我们设计了功能分析，使我们能够探索Orco功能和药理学的结构基础，无论是在体外使用突变分析，还是在体内。总之，这些研究将为Orco通道的功能和调节机制提供原子洞察力，为合理设计小分子驱避剂奠定基础，这些驱避剂可以扰乱人类疾病媒介昆虫中的气味检测和寻找宿主的行为。

DESCRIPTION (provided by applicant): Insects are the primary vectors for many deadly diseases. Mosquitoes and other blood-feeding insects are attracted to their human hosts via volatile olfactory cues. Consequently, the transmission of insect-borne diseases could be effectively controlled through strategies that target insect odorant receptors, disrupt the initial detection of human volatiles and prevent mosquitoes and other vectors from locating their human hosts. Insect odorant receptors are thought to 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 an absolutely essential role in olfactory transduction. Unfortunately as these receptors lack any structural homologs, many of their most fundamental structural and functional properties remain elusive, precluding sufficient mechanistic understanding to guide drug design. The objective of this proposal is to bring much-needed molecular insight to insect odorant receptors. We plan to perform X-ray crystallographic studies on Orco, alone and in complex with previously identified small-molecule agonists and antagonists, as a strategy to reveal the structural and mechanistic basis for modulation in this critical olfactory channel. In parallel, we have devised functional assays that allow us to probe the structural basis for Orco function and pharmacology, both in vitro using mutational analysis, and in vivo. Together, these studies will provide atomic insight into the mechanism by which the Orco channel functions and can be modulated, laying the foundation for the rational design of small molecule repellents that disrupt odor detection and host-seeking behavior in insect vectors of human disease.