Chronic pain accounts for nearly two-thirds of conditions eligible for medical cannabis licenses, yet the mechanisms underlying cannabis-induced analgesia remain poorly understood. The principal phytocannabinoids, the psychoactive Δ⁹-tetrahydrocannabinol (THC) and non-psychoactive cannabidiol (CBD), exhibit comparable efficacy in pain management. Notably, THC functions as an agonist of cannabinoid receptor 1 (CB1), whereas CBD shows minimal activity on CB1 and CB2 receptors. Elucidating the molecular targets through which phytocannabinoids modulate the pain system is required for advancing our understanding of the pain pathway and optimizing medical cannabis therapies. Transient receptor potential ankyrin 1 (TRPA1), a pivotal chemosensor in the pain pathway, has been identified as a phytocannabinoid target. Unlike most TRPA1 activators, phytocannabinoid activation is not mediated through the electrophilic binding site, suggesting an alternative mechanism. Here, we identified the human TRPA1 channel cannabinoid-binding site (CBS) and demonstrated that mutations at residue Y840 abolished responses to both THC and CBD at saturating concentrations, indicating a shared primary binding site. Molecular modeling revealed distinct interactions of THC and CBD with the Y840 residue within the CBS. Additionally, CBD binds to the adjacent general anesthetic binding site at oversaturating concentrations. Our findings define the CBS of TRPA1 as overlapping with and adjacent to binding sites for other allosteric activators, suggesting that TRPA1 possesses a highly adaptable domain for binding non-electrophilic activators. This underscores its unique role as a chemosensor in the pain pathway. Furthermore, our results provide new insights into the molecular mechanisms of cannabinoid-induced analgesia and identify novel targets for pain management therapies.

Sweet taste is a cue for calorie-rich food and is innately attractive to animals, including humans. In the context of modern diets, attraction to sweetness presents a significant challenge to human health. Most known sugars and sweeteners bind to the Venus Fly Trap domain of T1R2 subunit of the sweet taste heterodimer. Because the sweet taste receptor structure has not been experimentally solved yet, a possible approach to finding sweet molecules is virtual screening using compatibility of candidate molecules to homology models of sugar-binding site. Here, the constructed structural models, docking and scoring schemes were validated by their ability to rank known sweet-tasting compounds higher than properties-matched random molecules. The best performing models were next used in virtual screening, retrieving recently patented sweeteners and providing novel predictions. © 2020 Elsevier Ltd

This study aimed at identifying whether the bitter-tasting amino acids l-arginine (l-ARG) and l-isoleucine (l-ILE) differentially regulate mechanisms of gastric acid secretion in human parietal cells (HGT-1 cells) via activation of bitter taste sensing receptors (T2Rs). In a first set of experiments, involvement of T2Rs in l-ARG and l-ILE-modulated proton secretion was demonstrated by co-treatment of HGT-1 cells with T2R antagonists. Subsequent whole genome screenings by means of cDNA arrays revealed T2R1 as a prominent target for both amino acids. Next, the functional role of T2R1 was verified by means of a T2R1 CRISPR-Cas9 knock-out approach. Here, the effect of l-ARG on proton secretion decreased by 65.7 ± 21.9% and the effect of l-ILE increased by 93.2 ± 24.1% in HGT-1 T2R1 ko versus HGT-1 wt cells (p < 0.05). Overall, our results indicate differential effects of l-ARG and l-ILE on proton secretion in HGT-1 cells and our molecular docking studies predict distinct binding for these amino acids in the binding site of T2R1. Further studies will elucidate whether the mechanism of differential effects involves structure-specific ligand-biased signaling of T2R1 or additional cellular targets. Copyright © 2019 American Chemical Society.

“Bitter” and “sweet” are frequently framed in opposition, both functionally and metaphorically, in regard to affective responses, emotion, and nutrition. This oppositional relationship is complicated by the fact that some molecules are simultaneously bitter and sweet. In some cases, a small chemical modification, or a chirality switch, flips the taste from sweet to bitter. Molecules humans describe as bitter are recognized by a 25-member subfamily of class A G-protein coupled receptors (GPCRs) known as TAS2Rs. Molecules humans describe as sweet are recognized by a TAS1R2/TAS1R3 heterodimer of class C GPCRs. Here we characterize the chemical space of bitter and sweet molecules: the majority of bitter compounds show higher hydrophobicity compared to sweet compounds, while sweet molecules have a wider range of sizes. Importantly, recent evidence indicates that TAS1Rs and TAS2Rs are not limited to the oral cavity; moreover, some bitterants are pharmacologically promiscuous, with the hERG potassium channel, cytochrome P450 enzymes, and carbonic anhydrases as common off-targets. Further focus on polypharmacology may unravel new physiological roles for tastant molecules. © 2018 Elsevier B.V.