Examination of the Molecular Mechanisms of Mosquito Odorant Receptors

蚊子的嗅觉系统已经成为减少蚊媒疾病传播的一种手段，包括疟疾、登革热出血热和西尼罗河脑炎。在这种感觉模式中，被称为气味剂的挥发性化合物启动嗅觉受体神经元（orn）的去极化，这些神经元位于嗅觉附属物的化学感觉感受器内。气味识别通过多种机制介导，其中一个机制集中在气味受体表面表达的多种气味受体（ORs）家族。逆转录酶被认为负责识别特定的气味并启动逆转录酶的去极化。在蚊子中，基于OR的气味检测功能单元由高度保守的共受体Orco和与气味特异性相关的发散OR组成。以前认为昆虫的逆转录酶与脊椎动物的逆转录酶类似，是g蛋白偶联受体。然而，现在看来昆虫的OR复合物作为配体门控离子通道起作用，但目前的机制模型尚不清楚。此外，保守残基的功能意义还有待确定。拟议的研究将集中于主要的非洲热带疟疾病媒冈比亚按蚊的口服补液量。本研究拟利用膜片钳电生理技术研究冈比亚按蚊OR （AgamOR）复合物的通道特性。此外，还将进行突变研究，以确定对AgamOR功能的各个方面至关重要的残基。虽然这些研究的实验重点将放在AgamOR的结构/功能上，但我们希望从所提出的实验中得到的分子模型将广泛适用于其他昆虫OR复合物。

The olfactory system of mosquitoes has been targeted as a means to decrease the spread of mosquito borne diseases, including malaria, dengue hemorrhagic fever, and West Nile encephalitis. In this sensory modality, volatile compounds known as odorants initiate depolarization of olfactory receptor neurons (ORNs), which are housed within chemosensory sensilla on the olfactory appendages. Odorant recognition is mediated through several mechanisms, one of which centers on a diverse family of odorant receptors (ORs) expressed on the surface of ORNs. ORs are believed to be responsible for recognizing specific odorants and initiating the depolarization of ORNs. In mosquitoes, the functional unit of OR-based odorant detection consists of a highly- conserved co-receptor, Orco, and a divergent OR associated with odorant specificity. It was previously believed that insect ORs acted as G-protein coupled receptors, similar to vertebrate ORs. However, it now appears that insect OR complexes function as ligand- gated ion channels, but the current mechanistic model remains unclear. Furthermore, the functional significance of conserved residues has yet to be determined. The proposed studies will focus on the ORs of the principal Afrotropical malaria vector mosquito, Anopheles gambiae. The proposed research plans to investigate the channel properties of various Anopheles gambiae OR (AgamOR) complexes using patch clamp electrophysiology. In addition, mutational studies to identify residues critical to various aspects of AgamOR function will also be performed. While the experimental focus of these studies will be on AgamOR structure/function, we expect that the molecular model derived from the proposed experiments will be broadly applicable to other insect OR complexes.