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Insect olfactory receptors are heteromeric ligand-gated ion channels

Abstract

In insects, each olfactory sensory neuron expresses between one and three ligand-binding members of the olfactory receptor (OR) gene family, along with the highly conserved and broadly expressed Or83b co-receptor1,2,3,4,5,6,7,8,9. The functional insect OR consists of a heteromeric complex of unknown stoichiometry but comprising at least one variable odorant-binding subunit and one constant Or83b family subunit10,11,12,13,14,15,16. Insect ORs lack homology to G-protein-coupled chemosensory receptors in vertebrates17 and possess a distinct seven-transmembrane topology with the amino terminus located intracellularly10,18. Here we provide evidence that heteromeric insect ORs comprise a new class of ligand-activated non-selective cation channels. Heterologous cells expressing silkmoth, fruitfly or mosquito heteromeric OR complexes showed extracellular Ca2+influx and cation-non-selective ion conductance on stimulation with odorant. Odour-evoked OR currents are independent of known G-protein-coupled second messenger pathways. The fast response kinetics and OR-subunit-dependent K+ ion selectivity of the insect OR complex support the hypothesis that the complex between OR and Or83b itself confers channel activity. Direct evidence for odorant-gated channels was obtained by outside-out patch-clamp recording of Xenopus oocyte and HEK293T cell membranes expressing insect OR complexes. The ligand-gated ion channel formed by an insect OR complex seems to be the basis for a unique strategy that insects have acquired to respond to the olfactory environment.

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Figure 1: Odorants activate a non-selective cation conductance in HeLa cells expressing multimeric insect ORs.
Figure 2: Insect OR activity is independent of G protein signalling.
Figure 3: Kinetic analysis of Ca 2+ and current responses of insect ORs in HeLa cells.
Figure 4: Excised outside-out patch-clamp recording of Or47a + Or83b currents measured in oocyte membranes.
Figure 5: Excised outside-out patch-clamp recording of insect OR currents measured in HEK293T membranes.

References

  1. Clyne, P. J. et al. A novel family of divergent seven-transmembrane proteins: candidate odorant receptors in Drosophila . Neuron 22, 327–338 (1999)

    Article  CAS  Google Scholar 

  2. Vosshall, L. B., Amrein, H., Morozov, P. S., Rzhetsky, A. & Axel, R. A spatial map of olfactory receptor expression in the Drosophila antenna. Cell 96, 725–736 (1999)

    Article  CAS  Google Scholar 

  3. Couto, A., Alenius, M. & Dickson, B. J. Molecular, anatomical, and functional organization of the Drosophila olfactory system. Curr. Biol. 15, 1535–1547 (2005)

    Article  CAS  Google Scholar 

  4. Dobritsa, A. A. et al. Integrating the molecular and cellular basis of odor coding in the Drosophila antenna. Neuron 37, 827–841 (2003)

    Article  CAS  Google Scholar 

  5. Elmore, T., Ignell, R., Carlson, J. R. & Smith, D. P. Targeted mutation of a Drosophila odor receptor defines receptor requirement in a novel class of sensillum. J. Neurosci. 23, 9906–9912 (2003)

    Article  CAS  Google Scholar 

  6. Fishilevich, E. & Vosshall, L. B. Genetic and functional subdivision of the Drosophila antennal lobe. Curr. Biol. 15, 1548–1553 (2005)

    Article  CAS  Google Scholar 

  7. Hallem, E. A. & Carlson, J. R. Coding of odors by a receptor repertoire. Cell 125, 143–160 (2006)

    Article  CAS  Google Scholar 

  8. Hallem, E. A., Ho, M. G. & Carlson, J. R. The molecular basis of odor coding in the Drosophila antenna. Cell 117, 965–979 (2004)

    Article  CAS  Google Scholar 

  9. Goldman, A. L., Van der Goes van Naters, W., Lessing, D., Warr, C. G. & Carlson, J. R. Coexpression of two functional odor receptors in one neuron. Neuron 45, 661–666 (2005)

    Article  CAS  Google Scholar 

  10. Benton, R., Sachse, S., Michnick, S. W. & Vosshall, L. B. Atypical membrane topology and heteromeric function of Drosophila odorant receptors in vivo . PLoS Biol. 4, e20 (2006)

    Article  Google Scholar 

  11. Larsson, M. C. et al. Or83b encodes a broadly expressed odorant receptor essential for Drosophila olfaction. Neuron 43, 703–714 (2004)

    Article  CAS  Google Scholar 

  12. Nakagawa, T., Sakurai, T., Nishioka, T. & Touhara, K. Insect sex-pheromone signals mediated by specific combinations of olfactory receptors. Science 307, 1638–1642 (2005)

    Article  ADS  CAS  Google Scholar 

  13. Neuhaus, E. M. et al. Odorant receptor heterodimerization in the olfactory system of Drosophila melanogaster . Nature Neurosci. 8, 15–17 (2005)

    Article  CAS  Google Scholar 

  14. Jones, W. D., Nguyen, T. A., Kloss, B., Lee, K. J. & Vosshall, L. B. Functional conservation of an insect odorant receptor gene across 250 million years of evolution. Curr. Biol. 15, R119–R121 (2005)

    Article  CAS  Google Scholar 

  15. Krieger, J., Klink, O., Mohl, C., Raming, K. & Breer, H. A candidate olfactory receptor subtype highly conserved across different insect orders. J. Comp. Physiol. [A] 189, 519–526 (2003)

    Article  CAS  Google Scholar 

  16. Pitts, R. J., Fox, A. N. & Zwiebel, L. J. A highly conserved candidate chemoreceptor expressed in both olfactory and gustatory tissues in the malaria vector Anopheles gambiae . Proc. Natl Acad. Sci. USA 101, 5058–5063 (2004)

    Article  ADS  CAS  Google Scholar 

  17. Wistrand, M., Kall, L. & Sonnhammer, E. L. A general model of G protein-coupled receptor sequences and its application to detect remote homologs. Protein Sci. 15, 509–521 (2006)

    Article  CAS  Google Scholar 

  18. Lundin, C. et al. Membrane topology of the Drosophila OR83b odorant receptor. FEBS Lett. 581, 5601–5604 (2007)

    Article  CAS  Google Scholar 

  19. Hallem, E. A., Nicole Fox, A., Zwiebel, L. J. & Carlson, J. R. Olfaction: mosquito receptor for human-sweat odorant. Nature 427, 212–213 (2004)

    Article  ADS  CAS  Google Scholar 

  20. de Bruyne, M., Clyne, P. J. & Carlson, J. R. Odor coding in a model olfactory organ: the Drosophila maxillary palp. J. Neurosci. 19, 4520–4532 (1999)

    Article  CAS  Google Scholar 

  21. de Bruyne, M., Foster, K. & Carlson, J. R. Odor coding in the Drosophila antenna. Neuron 30, 537–552 (2001)

    Article  CAS  Google Scholar 

  22. Sato, K. & Suzuki, N. The contribution of Ca2+-activated Cl- conductance to amino-acid-induced inward current responses of ciliated olfactory neurons of the rainbow trout. J. Exp. Biol. 203, 253–262 (2000)

    CAS  PubMed  Google Scholar 

  23. Firestein, S., Shepherd, G. M. & Werblin, F. S. Time course of the membrane current underlying sensory transduction in salamander olfactory receptor neurones. J. Physiol. (Lond.) 430, 135–158 (1990)

    Article  CAS  Google Scholar 

  24. Kaissling, K. E. Peripheral mechanisms of pheromone reception in moths. Chem. Senses 21, 257–268 (1996)

    Article  CAS  Google Scholar 

  25. Zagotta, W. N. Membrane biology: permutations of permeability. Nature 440, 427–429 (2006)

    Article  ADS  CAS  Google Scholar 

  26. Lacampagne, A., Gannier, F., Argibay, J., Garnier, D. & Le Guennec, J. Y. The stretch-activated ion channel blocker gadolinium also blocks L-type calcium channels in isolated ventricular myocytes of the guinea-pig. Biochim. Biophys. Acta 1191, 205–208 (1994)

    Article  CAS  Google Scholar 

  27. Kanzaki, M. et al. Molecular identification of a eukaryotic, stretch-activated nonselective cation channel. Science 285, 882–886 (1999)

    Article  CAS  Google Scholar 

  28. Halaszovich, C. R., Zitt, C., Jungling, E. & Luckhoff, A. Inhibition of TRP3 channels by lanthanides. Block from the cytosolic side of the plasma membrane. J. Biol. Chem. 275, 37423–37428 (2000)

    Article  CAS  Google Scholar 

  29. Murakami, M. & Kijima, H. Transduction ion channels directly gated by sugars on the insect taste cell. J. Gen. Physiol. 115, 455–466 (2000)

    Article  CAS  Google Scholar 

  30. Nagel, G. et al. Channelrhodopsin-1: a light-gated proton channel in green algae. Science 296, 2395–2398 (2002)

    Article  ADS  CAS  Google Scholar 

  31. Wicher, D. et al. Drosophila odorant receptors are both ligand-gated and cyclic nucleotide-activated cation channels. Nature 10.1038/nature06861 (this issue)

  32. Katada, S., Nakagawa, T., Kataoka, H. & Touhara, K. Odorant response assays for a heterologously expressed olfactory receptor. Biochem. Biophys. Res. Commun. 305, 964–969 (2003)

    Article  CAS  Google Scholar 

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Acknowledgements

K.S. and K.T. thank M. Tominaga, Y. Okamura and Y. Kubo for discussion. M.P. and L.B.V. thank D. Gadsby, and Gadsby laboratory members N. Vedovato, P. Artigas, P. Hoff and A. Kovacs. DNA clones were provided by R. Y. Tsien (mRFP), T.-Y. Chen (CNGs) and A. Kovacs (CFTR). This work was supported in part by grants from PROBRAIN and MEXT of Japan to K.T., by a grant from the Foundation for the National Institutes of Health to R. Axel and L.B.V. through the Grand Challenges in Global Health Initiative, and by a National Institutes of Health (NIH) grant to L.B.V., a postdoctoral fellowship from the Japan Society for the Promotion of Science (JSPS) to T.N., and an NIH US–Japan Brain Research Cooperative Program grant and Japan-US Cooperative Science Program funding from the JSPS to K.T. and L.B.V.

Author Contributions Experiments were performed by K.S. (Figs 1, 2a–d, 3 and 5, and Supplementary Figs 1, 2, 3a, 4, 5a, b, 6 and 8), M.P. (Fig. 4 and Supplementary Figs 3b–d, 5c and 7), Takao N. (Fig. 2e) and Tatsuro N. (Supplementary Fig. 5b). K.T. and L.B.V. conceived and supervised the experiments, and wrote the paper with K.S. and M.P.

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Correspondence to Kazushige Touhara.

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Sato, K., Pellegrino, M., Nakagawa, T. et al. Insect olfactory receptors are heteromeric ligand-gated ion channels. Nature 452, 1002–1006 (2008). https://doi.org/10.1038/nature06850

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