Urotensin-II peptidomimetic incorporating a non-reducible 1,5-triazole disulfide bond reveals a pseudo-irreversible covalent binding mechanism to the urotensin G-protein coupled receptor

Pacifico, S., Kerckhoffs, A., Fallow, A. J., Foreman, R. E., Guerrini, R., McDonald, J., Lambert, D. G. and Jamieson, A. G. (2017) Urotensin-II peptidomimetic incorporating a non-reducible 1,5-triazole disulfide bond reveals a pseudo-irreversible covalent binding mechanism to the urotensin G-protein coupled receptor. Organic and Biomolecular Chemistry, 15(21), pp. 4704-4710. (doi: 10.1039/C7OB00959C) (PMID:28524918)

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Abstract

The urotensin-II receptor (UTR) is a class A GPCR that predominantly binds to the pleiotropic cyclic peptide urotensin-II (U-II). U-II is constrained by a disulfide bridge that induces a β-turn structure and binds pseudo-irreversibly to UTR and is believed to result in a structural rearrangement of the receptor. However, it is not well understood how U-II binds pseudo-irreversibly and the nature of the reorganization of the receptor that results in G-protein activation. Here we describe a series of U-II peptidomimetics incorporating a non-reducible disulfide bond structural surrogate to investigate the feasibility that native U-II binds to the G protein-coupled receptor through disulfide bond shuffling as a mechanism of covalent interaction. Disubstituted 1,2,3-triazoles were designed with the aid of computational modeling as a non-reducible mimic of the disulfide bridge (Cys5–Cys10) in U-II. Solid phase synthesis using CuAAC or RuAAC as the key macrocyclisation step provided four analogues of U-II(4–11) incorporating either a 1,5-triazole bridge (5, 6) or 1,4-triazole bridge (9, 10). Biological evaluation of compounds 5, 6, 9 and 10 was achieved using in vitro [125I]UII binding and [Ca2+]i assays at recombinant human UTR. Compounds 5 and 6 demonstrated high affinity (KD ∼ 10 nM) for the UTR and were also shown to bind reversibly as predicted and activate the UTR to increase [Ca2+]i. Importantly, our results provide new insight into the mechanism of covalent binding of U-II with the UTR.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Jamieson, Professor Andrew
Authors: Pacifico, S., Kerckhoffs, A., Fallow, A. J., Foreman, R. E., Guerrini, R., McDonald, J., Lambert, D. G., and Jamieson, A. G.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Organic and Biomolecular Chemistry
Publisher:Royal Society of Chemistry
ISSN:1477-0520
ISSN (Online):1477-0539
Published Online:12 May 2017
Copyright Holders:Copyright © 2017 The Royal Society of Chemistry
First Published:First published in Organic and Biomolecular Chemistry 15(21): 4704-4710
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
758941DNA Templated Synthesis of De Novo Protein ??-MotifsAndrew JamiesonLeverhulme Trust (LEVERHUL)RPG-2014-372SCHOOL OF CHEMISTRY