Department of Biology, Lund University, Lund, Sweden.
Division of Biochemistry and Structural Biology, Department of Chemistry, Lund University, Lund, Sweden.
Sci Rep. 2018 Feb 22;8(1):3489. doi: 10.1038/s41598-018-21631-3.
Insect olfactory receptors are routinely expressed in heterologous systems for functional characterisation. It was recently discovered that the essential olfactory receptor co-receptor (Orco) of the Hessian fly, Mayetiola destructor (Mdes), does not respond to the agonist VUAA1, which activates Orco in all other insects analysed to date. Here, using a mutagenesis-based approach we identified three residues in MdesOrco, located in different transmembrane helices as supported by 3D modelling, that confer sensitivity to VUAA1. Reciprocal mutations in Drosophila melanogaster (Dmel) and the noctuid moth Agrotis segetum (Aseg) Orcos diminish sensitivity of these proteins to VUAA1. Additionally, mutating these residues in DmelOrco and AsegOrco compromised odourant receptor (OR) dependent ligand-induced Orco activation. In contrast, both wild-type and VUAA1-sensitive MdesOrco were capable of forming functional receptor complexes when coupled to ORs from all three species, suggesting unique complex properties in M. destructor, and that not all olfactory receptor complexes are "created" equal.
昆虫嗅觉受体通常在异源系统中表达，用于功能表征。最近发现，黑森果蝇（Mayetiola destructor，Mdes）的必需嗅觉受体共受体（Orco）对迄今为止分析的所有其他昆虫中激活 Orco 的激动剂 VUAA1 没有反应。在这里，我们使用基于诱变的方法鉴定了 MdesOrco 中的三个残基，这些残基位于不同的跨膜螺旋中，这得到了 3D 建模的支持，这些残基赋予了对 VUAA1 的敏感性。在果蝇（Drosophila melanogaster，Dmel）和夜蛾（Agrotis segetum，Aseg）Orcos 中的同源突变降低了这些蛋白对 VUAA1 的敏感性。此外，在 DmelOrco 和 AsegOrco 中突变这些残基会损害这些蛋白对气味受体（OR）依赖性配体诱导的 Orco 激活。相比之下，野生型和对 VUAA1 敏感的 MdesOrco 都能够与来自这三个物种的 OR 形成功能性受体复合物，这表明在 M. destructor 中存在独特的复合物特性，并非所有嗅觉受体复合物都是“相同”的。
