Identification of a Crucial Amino Acid in the Helix Position 6.51 of Human Tachykinin Neurokinin 1 and 3 Receptors Contributing to the Insurmountable Mode of Antagonism by Dual NK1/NK3 Antagonists
Abstract:The neurokinins are neuropeptides that elicit their effect through three GPCRs called NK(1), NK(2), and NK(3). Compounds 5 and 6 are dual hNK(1) (K(i) of 0.7 and 0.3 nM) and hNK(3) (K(i) of 2.9 and 1.7 nM) antagonists. Both compounds exhibit an insurmountable mode of antagonism at hNK(1), whereas at hNK(3), they differ in that 5 is an insurmountable but 6 a surmountable antagonist. Using homology modeling and site-directed mutagenesis, hNK(1)-Phe264 and hNK(3)-Tyr315 were found to be the molecular determinants… Show more
“…Overall, 15 residues are involved in the binding of aprepitant, of which 10 are highly conserved across the neurokinin receptor subfamily (Supplementary Figure 6). However, the key residue F264 6.51 , which, to our knowledge, is not known to be involved in the ligand binding of NK1R, is presented as tyrosine in NK2R and NK3R 33 . In the NK1R structure, the residue F264 6.51 forms a strong edge–π interaction with the bis-trifluomethyl-phenyl ring of aprepitant, and the substitution of the phenyl group with the phenolic group may disrupt the interaction and cause a spatial clash with the ligand.…”
Neurokinin 1 receptor (NK1R) has key regulating functions in the central and peripheral nervous systems, and NK1R antagonists such as aprepitant have been approved for treating chemotherapy-induced nausea and vomiting. However, the lack of data on NK1R structure and biochemistry has limited further drug development targeting this receptor. Here, we combine NMR spectroscopy and X-ray crystallography to provide dynamic and static characterisation of the binding mode of aprepitant in complexes with human NK1R variants. 19F-NMR showed a slow off-rate in the binding site, where aprepitant occupies multiple substates that exchange with frequencies in the millisecond range. The environment of the bound ligand is affected by the amino acid in position 2.50, which plays a key role in ligand binding and receptor signaling in class A GPCRs. Crystal structures now reveal how receptor signaling relates to the conformation of the conserved NP7.50xxY motif in transmembrane helix VII.
“…Overall, 15 residues are involved in the binding of aprepitant, of which 10 are highly conserved across the neurokinin receptor subfamily (Supplementary Figure 6). However, the key residue F264 6.51 , which, to our knowledge, is not known to be involved in the ligand binding of NK1R, is presented as tyrosine in NK2R and NK3R 33 . In the NK1R structure, the residue F264 6.51 forms a strong edge–π interaction with the bis-trifluomethyl-phenyl ring of aprepitant, and the substitution of the phenyl group with the phenolic group may disrupt the interaction and cause a spatial clash with the ligand.…”
Neurokinin 1 receptor (NK1R) has key regulating functions in the central and peripheral nervous systems, and NK1R antagonists such as aprepitant have been approved for treating chemotherapy-induced nausea and vomiting. However, the lack of data on NK1R structure and biochemistry has limited further drug development targeting this receptor. Here, we combine NMR spectroscopy and X-ray crystallography to provide dynamic and static characterisation of the binding mode of aprepitant in complexes with human NK1R variants. 19F-NMR showed a slow off-rate in the binding site, where aprepitant occupies multiple substates that exchange with frequencies in the millisecond range. The environment of the bound ligand is affected by the amino acid in position 2.50, which plays a key role in ligand binding and receptor signaling in class A GPCRs. Crystal structures now reveal how receptor signaling relates to the conformation of the conserved NP7.50xxY motif in transmembrane helix VII.
“…While selective NKR antagonists in clinical trials had rather disappointing outcomes, new hopes are now given to dual and/or triple NKR ligands for the treatment of diverse pathologies. , We therefore aimed to develop a set of models combining NK 1 R, NK 2 R, and NK 3 R activity, which was able to identify the majority of NKR-active compounds from our literature data set and at the same time finds as few decoys as possible. A way to achieve this goal is the generation of various models, the hit lists of which are complementary to each other .…”
Section: Resultsmentioning
confidence: 99%
“…The unsatisfactory results of subtype receptor-selective compounds in clinical trials shifted the research efforts toward nonselective NKR antagonists favoring the antagonism of more than one NKR in accordance with the activity profiles of the endogenous ligands SP, NKA, and NKB. For example, targeting the treatment of schizophrenia, Hoffmann–La Roche proceeded to investigate dual NK 1 R-/NK 3 R-antagonists, while Novartis 2011 concentrated on the development of compounds binding to all three receptors …”
Neurokinin receptors (NKRs) have been shown to be involved in many physiological processes, rendering them promising novel drug targets, but also making them the possible cause for side effects of several drugs. Aiming to answer the question whether the binding to NKRs could have a share in the side effects or even the desired effects of already licensed drugs, we generated a set of ligand-based common feature pharmacophore models based on the structural information about subtype-selective and nonselective NKR antagonists and screened an in-house database mainly composed of licensed drugs. The prospective pharmacological investigations of the virtual hits haloperidol, eprazinone, and fenbutrazate confirmed them to be NKR ligands in vitro. By the identification of licensed drugs as so far unknown NKR ligands, this study contributes to establishing an activity profile of the investigated compounds and confirms the presented pharmacophore models as useful tools for this purpose.
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