Presentation Details
| Intracellular and Dual-Site Inhibition of a Bitter Taste GPCR Nitsan Dallal, Gil Daniel Paz, Noga Nir Marom, Yael Keselman, Shir Eyal, Evgenii Ziaikin, Alon Rainish, Lior Peri, Einav Malach, Masha Y.Niv. The Robert H.Smith Faculty of Agriculture, Food and Environment, Institute of Biochemistry, Food Science and Nutrition, The Hebrew University of Jerusalem, Rehovot, Israel |
Abstract
Bitter taste receptors (TAS2Rs) are G protein–coupled receptors expressed in both gustatory and extraoral tissues and involved in diverse physiological processes including immune defense, airway signaling and cancer biology. TAS2R14 is one of the most broadly tuned members of this family, responding to hundreds of structurally diverse ligands. Recent cryo-electron microscopy structures revealed that, in addition to the canonical extracellular ligand-binding pocket, TAS2R14 contains an intracellular binding site located near the G protein interface, suggesting a potential alternative mechanism for receptor inhibition via this lower pocket.
Here, we investigated the binding sites of several TAS2R14 antagonists. Using site-directed mutagenesis, IP-One functional assays and computational co-folding approaches, we found that most antagonists are primarily sensitive to mutations in the intracellular binding site and are capable of inhibiting both TAS2R14 and TAS2R16, another bitter taste receptor. One antagonist was sensitive to mutations in both extracellular and intracellular pockets and selectively inhibited TAS2R14. Co-folding models supported these findings, revealing distinct inhibitory modes in which some ligands predominantly engage the intracellular pocket, while others interact with both binding sites.
Together, these results uncover distinct inhibitory mechanisms among TAS2R antagonists and highlight the intracellular binding site as a promising target for the rational design of bitter taste receptor inhibitors with defined receptor specificity for both sensory and extraoral functions.
No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.
Here, we investigated the binding sites of several TAS2R14 antagonists. Using site-directed mutagenesis, IP-One functional assays and computational co-folding approaches, we found that most antagonists are primarily sensitive to mutations in the intracellular binding site and are capable of inhibiting both TAS2R14 and TAS2R16, another bitter taste receptor. One antagonist was sensitive to mutations in both extracellular and intracellular pockets and selectively inhibited TAS2R14. Co-folding models supported these findings, revealing distinct inhibitory modes in which some ligands predominantly engage the intracellular pocket, while others interact with both binding sites.
Together, these results uncover distinct inhibitory mechanisms among TAS2R antagonists and highlight the intracellular binding site as a promising target for the rational design of bitter taste receptor inhibitors with defined receptor specificity for both sensory and extraoral functions.
No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.
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