Examination of the Molecular Mechanisms of Mosquito Odorant Receptors

蚊子的嗅觉系统一直是减少蚊子传播疾病传播的一种手段，包括疟疾、登革出血热和西尼罗河脑炎。在这种感觉方式中，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，ORN被安置在嗅觉附属器上的化学感觉器内。气味识别是通过几种机制介导的，其中一种机制集中在ORN表面表达的气味受体（OR）的不同家族。据信ORs负责识别特定的气味剂并引发ORN的去极化。在蚊子中，基于OR的气味检测的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OR作为G蛋白偶联受体，类似于脊椎动物OR。然而，现在看来，昆虫OR复合物作为配体门控离子通道发挥功能，但目前的机制模型仍不清楚。此外，保守残基的功能意义尚未确定。 拟议的研究将侧重于主要非洲热带疟疾媒介蚊子冈比亚按蚊的OR。拟议的研究计划调查的各种冈比亚按蚊OR（AgamOR）复合物的通道特性，使用膜片钳电生理。此外，还将进行突变研究以鉴定对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是AgamOR结构/功能，我们预计，来自拟议的实验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.