Shim Jaewon, Lee Youngseok, Jeong Yong Taek, Kim Yonjung, Lee Min Goo, Montell Craig, Moon Seok Jun
Department of Oral Biology, BK21 PLUS Project Yonsei University College of Dentistry, Yonsei-ro 50-1, Seodaemun-gu, Seoul 120-752, Korea.
Division of Functional Food Research, Korea Food Research Institute, Seongnam, Gyeonggi-do 463-746, Korea.
Nat Commun. 2015 Nov 16;6:8867. doi: 10.1038/ncomms9867.
The ability to detect toxic compounds in foods is essential for animal survival. However, the minimal subunit composition of gustatory receptors required for sensing aversive chemicals in Drosophila is unknown. Here we report that three gustatory receptors, GR8a, GR66a and GR98b function together in the detection of L-canavanine, a plant-derived insecticide. Ectopic co-expression of Gr8a and Gr98b in Gr66a-expressing, bitter-sensing gustatory receptor neurons (GRNs) confers responsiveness to L-canavanine. Furthermore, misexpression of all three Grs enables salt- or sweet-sensing GRNs to respond to L-canavanine. Introduction of these Grs in sweet-sensing GRNs switches L-canavanine from an aversive to an attractive compound. Co-expression of GR8a, GR66a and GR98b in Drosophila S2 cells induces an L-canavanine-activated nonselective cation conductance. We conclude that three GRs collaborate to produce a functional L-canavanine receptor. Thus, our results clarify the full set of GRs underlying the detection of a toxic tastant that drives avoidance behaviour in an insect.
检测食物中的有毒化合物的能力对动物生存至关重要。然而，果蝇中感知厌恶化学物质所需的味觉受体的最小亚基组成尚不清楚。在此我们报告，三种味觉受体GR8a、GR66a和GR98b共同作用于L-刀豆氨酸的检测，L-刀豆氨酸是一种植物源杀虫剂。Gr8a和Gr98b在表达Gr66a的苦味味觉受体神经元（GRNs）中的异位共表达赋予了对L-刀豆氨酸的反应性。此外，所有三种Grs的错误表达使盐味或甜味感知GRNs能够对L-刀豆氨酸作出反应。在甜味感知GRNs中引入这些Grs会使L-刀豆氨酸从一种厌恶化合物转变为一种有吸引力的化合物。GR8a、GR66a和GR98b在果蝇S2细胞中的共表达诱导了一种L-刀豆氨酸激活的非选择性阳离子电导。我们得出结论，三种GRs协同作用产生功能性的L-刀豆氨酸受体。因此，我们的结果阐明了检测一种导致昆虫产生回避行为的有毒味觉物质的完整GRs组合。
