The molecular basis of sugar detection by an insect taste receptor.

Publisher: Nature Publishing Group Country of Publication: England NLM ID: 0410462 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1476-4687 (Electronic) Linking ISSN: 00280836 NLM ISO Abbreviation: Nature Subsets: MEDLINE

Publication: Basingstoke : Nature Publishing Group
Original Publication: London, Macmillan Journals ltd.

Bombyx*/metabolism ; Bombyx*/chemistry ; Insect Proteins*/chemistry ; Insect Proteins*/genetics ; Insect Proteins*/metabolism ; Insect Proteins*/ultrastructure ; Receptors, G-Protein-Coupled*/chemistry ; Receptors, G-Protein-Coupled*/genetics ; Receptors, G-Protein-Coupled*/metabolism ; Receptors, G-Protein-Coupled*/ultrastructure ; Sugars*/metabolism ; Sugars*/chemistry ; Taste*/physiology; Animals ; Allosteric Regulation ; Binding Sites ; Cryoelectron Microscopy ; Fructose/metabolism ; Fructose/chemistry ; Ligands ; Models, Molecular ; Molecular Docking Simulation ; Protein Binding ; Sorbose/chemistry ; Sorbose/metabolism ; Substrate Specificity

Animals crave sugars because of their energy potential and the pleasurable sensation of tasting sweetness. Yet all sugars are not metabolically equivalent, requiring mechanisms to detect and differentiate between chemically similar sweet substances. Insects use a family of ionotropic gustatory receptors to discriminate sugars ¹ , each of which is selectively activated by specific sweet molecules ^2-6 . Here, to gain insight into the molecular basis of sugar selectivity, we determined structures of Gr9, a gustatory receptor from the silkworm Bombyx mori (BmGr9), in the absence and presence of its sole activating ligand, D-fructose. These structures, along with structure-guided mutagenesis and functional assays, illustrate how D-fructose is enveloped by a ligand-binding pocket that precisely matches the overall shape and pattern of chemical groups in D-fructose. However, our computational docking and experimental binding assays revealed that other sugars also bind BmGr9, yet they are unable to activate the receptor. We determined the structure of BmGr9 in complex with one such non-activating sugar, L-sorbose. Although both sugars bind a similar position, only D-fructose is capable of engaging a bridge of two conserved aromatic residues that connects the pocket to the pore helix, inducing a conformational change that allows the ion-conducting pore to open. Thus, chemical specificity does not depend solely on the selectivity of the ligand-binding pocket, but it is an emergent property arising from a combination of receptor-ligand interactions and allosteric coupling. Our results support a model whereby coarse receptor tuning is derived from the size and chemical characteristics of the pocket, whereas fine-tuning of receptor activation is achieved through the selective engagement of an allosteric pathway that regulates ion conduction.
(© 2024. The Author(s).)

Kent, L. B. & Robertson, H. M. Evolution of the sugar receptors in insects. BMC Evol. Biol. 9, 41–20 (2009). (PMID: 19226470266740510.1186/1471-2148-9-41)
Sato, K., Tanaka, K. & Touhara, K. Sugar-regulated cation channel formed by an insect gustatory receptor. Proc. Natl Acad. Sci. USA 108, 11680–11685 (2011). (PMID: 21709218313628610.1073/pnas.1019622108)
Miyamoto, T., Slone, J., Song, X. & Amrein, H. A fructose receptor functions as a nutrient sensor in the Drosophila brain. Cell 151, 1113–1125 (2012). (PMID: 23178127350941910.1016/j.cell.2012.10.024)
Tsuneto, K. et al. BmGr10 is a putative functional gustatory receptor in the myo-inositol neuron in the epipharyngeal sensillum. J. Insect Biotechnol. Sericol. 88, 7–15 (2019).
Chyb, S., Dahanukar, A., Wickens, A. & Carlson, J. R. Drosophila Gr5a encodes a taste receptor tuned to trehalose. Proc. Natl Acad. Sci. USA 100, 14526–14530 (2003). (PMID: 1452322930411310.1073/pnas.2135339100)
Freeman, E. G., Wisotsky, Z. & Dahanukar, A. Detection of sweet tastants by a conserved group of insect gustatory receptors. Proc. Natl Acad. Sci. USA 111, 1598–1603 (2014). (PMID: 24474785391060010.1073/pnas.1311724111)
Lee, A. A. & Owyang, C. Sugars, sweet taste receptors, and brain responses. Nutrients 9, 653 (2017). (PMID: 28672790553777310.3390/nu9070653)
Stanhope, K. L. Sugar consumption, metabolic disease and obesity: the state of the controversy. Crit. Rev. Clin. Lab. Sci. 53, 52–67 (2016). (PMID: 2637661910.3109/10408363.2015.1084990)
Yarmolinsky, D. A., Zuker, C. S. & Ryba, N. J. P. Common sense about taste: from mammals to insects. Cell 139, 234–244 (2009). (PMID: 19837029393651410.1016/j.cell.2009.10.001)
Nelson, G. et al. Mammalian sweet taste receptors. Cell 106, 381–390 (2001). (PMID: 1150918610.1016/S0092-8674(01)00451-2)
Chen, T.-W. et al. Ultrasensitive fluorescent proteins for imaging neuronal activity. Nature 499, 295–300 (2013). (PMID: 23868258377779110.1038/nature12354)
Nicolson, S. W. & Thornburg, R. W. in Nectaries and Nectar (eds Nicolson, S. W. et al.) 215–264 (Springer, 2007).
Butterwick, J. A. et al. Cryo-EM structure of the insect olfactory receptor Orco. Nature 560, 447–452 (2018). (PMID: 30111839612998210.1038/s41586-018-0420-8)
del Mármol, J., Yedlin, M. A. & Ruta, V. The structural basis of odorant recognition in insect olfactory receptors. Nature 597, 126–131 (2021). (PMID: 34349260841059910.1038/s41586-021-03794-8)
Sullivan, S. L. Mammalian chemosensory receptors. Neuroreport 13, A9–A17 (2002). (PMID: 1192490510.1097/00001756-200201210-00003)
Morinaga, S. et al. Structural model for ligand binding and channel opening of an insect gustatory receptor. J. Biol. Chem. 298, 102573 (2022). (PMID: 36209821964342510.1016/j.jbc.2022.102573)
Sinnott, M. L. Carbohydrate Chemistry and Biochemistry (RSC Publishing, 2013).
Angyal, S. & Bethell, G. Conformational analysis in carbohydrate chemistry. III. The ¹³ C N.M.R. spectra of the hexuloses. Aust. J. Chem. 29, 1249–1265 (1976). (PMID: 10.1071/CH9761249)
Eberhardt, J., Santos-Martins, D., Tillack, A. & Forli, S. AutoDock Vina 1.2.0: new docking methods, expanded force field, and Python bindings. J. Chem. Inf. Model. 61, 3891–3898 (2021).
Trott, O. & Olson, A. J. AutoDock Vina: improving the speed and accuracy of docking with a new scoring function, efficient optimization, and multithreading. J. Comput. Chem. 31, 455–461 (2010). (PMID: 19499576304164110.1002/jcc.21334)
Hudson, K. L. et al. Carbohydrate–aromatic interactions in proteins. J. Am. Chem. Soc. 137, 15152–15160 (2015). (PMID: 26561965467603310.1021/jacs.5b08424)
Renthal, R. & Chen, L. Y. Tunnel connects lipid bilayer to occluded odorant-binding site of insect olfactory receptor. Biophys. Chem. 289, 106862 (2022). (PMID: 3593383410.1016/j.bpc.2022.106862)
Robertson, H. M. The insect chemoreceptor superfamily is ancient in animals. Chem. Senses 40, 609–614 (2015). (PMID: 2635493210.1093/chemse/bjv046)
Benton, R. & Himmel, N. J. Structural screens identify candidate human homologs of insect chemoreceptors and cryptic Drosophila gustatory receptor-like proteins. eLife 12, e85537 (2023). (PMID: 36803935999809010.7554/eLife.85537)
Billesbølle, C. B. et al. Structural basis of odorant recognition by a human odorant receptor. Nature 615, 742–749 (2023). (PMID: 369225911058073210.1038/s41586-023-05798-y)
Nuemket, N. et al. Structural basis for perception of diverse chemical substances by T1r taste receptors. Nat. Commun. 8, 15530 (2017). (PMID: 28534491545751210.1038/ncomms15530)
Pfister, P. et al. Odorant receptor inhibition is fundamental to odor encoding. Curr. Biol. 30, 2574–2587 (2020). (PMID: 3247036510.1016/j.cub.2020.04.086)
Hallem, E. A. & Carlson, J. R. Coding of odors by a receptor repertoire. Cell 125, 143–160 (2006). (PMID: 1661589610.1016/j.cell.2006.01.050)
Ma, D. et al. Structural basis for sugar perception by Drosophila gustatory receptors. Science 383, eadj260 (2024).
Goehring, A. et al. Screening and large-scale expression of membrane proteins in mammalian cells for structural studies. Nat. Protocols 9, 2574–2585 (2014). (PMID: 2529915510.1038/nprot.2014.173)
Schmidt, T. G. M., Koepke, J., Frank, R. & Skerra, A. Molecular interaction between the Strep-tag affinity peptide and its cognate target, streptavidin. J. Mol. Biol. 255, 753–766 (1996). (PMID: 863697610.1006/jmbi.1996.0061)
Pédelacq, J.-D., Cabantous, S., Tran, T., Terwilliger, T. C. & Waldo, G. S. Engineering and characterization of a superfolder green fluorescent protein. Nat. Biotechnol. 24, 79–88 (2006). (PMID: 1636954110.1038/nbt1172)
Gasteiger, E. et al. in The Proteomics Protocols Handbook (eds Walker, J. M. et al.) 571–607 (Humana, 2005).
Mastronarde, D. N. Automated electron microscope tomography using robust prediction of specimen movements. J. Struct. Biol. 152, 36–51 (2005). (PMID: 1618256310.1016/j.jsb.2005.07.007)
Zheng, S. Q. et al. MotionCor2: anisotropic correction of beam-induced motion for improved cryo-electron microscopy. Nat. Methods 14, 331–332 (2017). (PMID: 28250466549403810.1038/nmeth.4193)
Rohou, A. & Grigorieff, N. CTFFIND4: fast and accurate defocus estimation from electron micrographs. J. Struct. Biol. 192, 216–221 (2015). (PMID: 26278980676066210.1016/j.jsb.2015.08.008)
Zivanov, J. et al. New tools for automated high-resolution cryo-EM structure determination in RELION-3. eLife 7, 163 (2018). (PMID: 10.7554/eLife.42166)
Punjani, A., Rubinstein, J. L., Fleet, D. J. & Brubaker, M. A. cryoSPARC: algorithms for rapid unsupervised cryo-EM structure determination. Nat. Methods 14, 290–296 (2017). (PMID: 2816547310.1038/nmeth.4169)
Rosenthal, P. B. & Henderson, R. Optimal determination of particle orientation, absolute hand, and contrast loss in single-particle electron cryomicroscopy. J. Mol. Biol. 333, 721–745 (2003). (PMID: 1456853310.1016/j.jmb.2003.07.013)
Pettersen, E. F. et al. UCSF ChimeraX: structure visualization for researchers, educators, and developers. Protein Sci. 30, 70–82 (2021). (PMID: 3288110110.1002/pro.3943)
Emsley, P., Lohkamp, B., Scott, W. G. & Cowtan, K. Features and development of Coot. Acta Crystallogr. D 66, 486–501 (2010). (PMID: 20383002285231310.1107/S0907444910007493)
Adams, P. D. et al. PHENIX: a comprehensive Python-based system for macromolecular structure solution. Acta Crystallogr. D 66, 213–221 (2010). (PMID: 20124702281567010.1107/S0907444909052925)
Moriarty, N. W., Grosse‐Kunstleve, R. W. & Adams, P. D. electronic Ligand Builder and Optimization Workbench (eLBOW): a tool for ligand coordinate and restraint generation. Acta Crystallogr. D 65, 1074–1080 (2009). (PMID: 19770504274896710.1107/S0907444909029436)
Williams, C. J. et al. MolProbity: more and better reference data for improved all‐atom structure validation. Protein Sci. 27, 293–315 (2018). (PMID: 2906776610.1002/pro.3330)
The PyMOL Molecular Graphics System v.2.0 (Schrödinger, LLC).
Smart, O. S., Neduvelil, J. G., Wang, X., Wallace, B. A. & Sansom, M. S. HOLE: a program for the analysis of the pore dimensions of ion channel structural models. J. Mol. Graph. 14, 354–360 (1996). (PMID: 919548810.1016/S0263-7855(97)00009-X)
Quiroga, R. & Villarreal, M. A. Vinardo: a scoring function based on Autodock Vina improves scoring, docking, and virtual screening. PLoS ONE 11, e0155183 (2016). (PMID: 27171006486519510.1371/journal.pone.0155183)
O’Boyle, N. M. et al. Open Babel: an open chemical toolbox. J. Cheminformatics 3, 33 (2011). (PMID: 10.1186/1758-2946-3-33)
Waterhouse, A. M., Procter, J. B., Martin, D. M. A., Clamp, M. & Barton, G. J. Jalview Version 2–a multiple sequence alignment editor and analysis workbench. Bioinformatics 25, 1189–1191 (2009). (PMID: 19151095267262410.1093/bioinformatics/btp033)
Mirdita, M. et al. ColabFold: making protein folding accessible to all. Nat. Methods 19, 679–682 (2022). (PMID: 35637307918428110.1038/s41592-022-01488-1)

RM1 GM149406 United States GM NIGMS NIH HHS

30237-26-4 (Fructose)
0 (Insect Proteins)
0 (Ligands)
0 (Receptors, G-Protein-Coupled)
NV2001607Y (Sorbose)
0 (Sugars)
0 (taste receptors, type 1)

Date Created: 20240306 Date Completed: 20240501 Latest Revision: 20240712

20240712

PMC11062906

10.1038/s41586-024-07255-w

38447670