Functions of Opsins in Drosophila Taste

Curr Biol. 2020 Apr 20;30(8):1367-1379.e6. doi: 10.1016/j.cub.2020.01.068. Epub 2020 Apr 2.

Abstract

Rhodopsin is a light receptor comprised of an opsin protein and a light-sensitive retinal chromophore. Despite more than a century of scrutiny, there is no evidence that opsins function in chemosensation. Here, we demonstrate that three Drosophila opsins, Rh1, Rh4, and Rh7, are needed in gustatory receptor neurons to sense a plant-derived bitter compound, aristolochic acid (ARI). The gustatory requirements for these opsins are light-independent and do not require retinal. The opsins enabled flies to detect lower concentrations of aristolochic acid by initiating an amplification cascade that includes a G-protein, phospholipase Cβ, and the TRP channel, TRPA1. In contrast, responses to higher levels of the bitter compound were mediated through direct activation of TRPA1. Our study reveals roles for opsins in chemosensation and raise questions concerning the original roles for these classical G-protein-coupled receptors.

Keywords: Drosophila; GPCR; TRP channel; chromophore; gustatory; labellum; opsin; phospholipase C; retinal; rhodopsin.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / metabolism
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / physiology*
  • Female
  • Male
  • Opsins / genetics*
  • Opsins / metabolism
  • Random Allocation
  • Taste / physiology*
  • Taste Perception / physiology*

Substances

  • Drosophila Proteins
  • Opsins