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Smith MT. Nonopioid analgesics discovery and the Valley of Death: EMA401 from concept to clinical trial. Pain 2022; 163:S15-S28. [PMID: 35984369 PMCID: PMC10578428 DOI: 10.1097/j.pain.0000000000002675] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Revised: 04/22/2022] [Accepted: 04/28/2022] [Indexed: 12/23/2022]
Affiliation(s)
- Maree T Smith
- Centre for Integrated Preclinical Drug Development, School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane, Queensland, Australia
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2
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Deleon KY, Patel AP, Kuczera K, Johnson CK, Jas GS. Structure and reorientational dynamics of angiotensin I and II: a microscopic physical insight. J Biomol Struct Dyn 2012; 29:671-90. [PMID: 22545998 DOI: 10.1080/07391102.2011.672631] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
We present a study of structural analysis and reorientational dynamics of Angiotensin I (AngI) and Angiotensin II (AngII) in aqueous solution. AngI is a decapeptide that acts as a precursor to the octapeptide AngII in the Renin-Angiotensin-Aldosterone system for blood pressure regulation. Experimental structural characterization of these peptides, carried out with circular dichroism and infrared spectroscopy, showed that the angiotensins are mostly disordered but exhibit a measurable population of ordered structures at room temperature. Interestingly, these change from the unordered polyproline-like conformation for AngI to a more compact and ordered conformation for AngII as the length of the peptide is decreased. Anisotropy decay measurements with picosecond time resolution indicate slower overall tumbling and a greater amplitude of internal motion in AngI compared to AngII, consistent with more compact and less flexible structure of the active form of the peptide. To model the microscopic behavior of the peptides, 2-μs molecular dynamics simulation trajectories were generated for AngI and AngII, at 300 K using the OPLS-AA potential and SPC water. The structures sampled in the simulations mostly agree with the experimental results, showing the prevalence of disordered structures, turns, and polyproline helices. Additionally, the computational results predict fewer sampled conformations, tighter side-chain packing and marked increase of Phe8 solvent accessibility upon AngI truncation to AngII. Our combined approach of experiment and extensive computer simulation thus yields new information on the conformational dynamics of the angiotensins, helping provide insight into the structural basis for the potency of AngI relative to AngII.
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Affiliation(s)
- Kristi Y Deleon
- Department of Chemistry, Biochemistry, Institute of Biomedical Studies, Baylor University, Waco, TX 76706, USA
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3
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4
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Multiple templates-based homology modeling enhances structure quality of AT1 receptor: validation by molecular dynamics and antagonist docking. J Mol Model 2010; 17:1565-77. [DOI: 10.1007/s00894-010-0860-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2010] [Accepted: 09/24/2010] [Indexed: 10/19/2022]
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5
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Kim JY, Kim MJ, Kim HT. Determination of a Binding Site of Cu, Ni, Mg, and Ca Metal Ions with Angiotensin II Peptide by Electrospray Tandem Mass Spectrometry. B KOREAN CHEM SOC 2010. [DOI: 10.5012/bkcs.2010.31.5.1377] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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6
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Vieira RFF, Casallanovo F, Marín N, Paiva ACM, Schreier S, Nakaie CR. Conformational properties of angiotensin II and its active and inactive TOAC-labeled analogs in the presence of micelles. Electron paramagnetic resonance, fluorescence, and circular dichroism studies. Biopolymers 2009; 92:525-37. [DOI: 10.1002/bip.21295] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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7
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Proulx CD, Holleran BJ, Lavigne P, Escher E, Guillemette G, Leduc R. Biological properties and functional determinants of the urotensin II receptor. Peptides 2008; 29:691-9. [PMID: 18155322 DOI: 10.1016/j.peptides.2007.10.027] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Revised: 10/12/2007] [Accepted: 10/19/2007] [Indexed: 02/07/2023]
Abstract
The urotensin II receptor (UT) is a member of the G protein-coupled receptor (GPCR) family and binds the cyclic undecapeptide urotensin II (U-II) as well as the octapeptide urotensin II-related peptide (URP). The active UT mediates pleiotropic effects through various signal transduction pathways, including coupling to G proteins and activating the mitogen-activated protein kinase pathway. Several highly conserved residues and motifs of class A GPCRs that are important for activity are found in UT. This review highlights some of the putative roles of these motifs in the binding, activation and desensitization of UT.
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Affiliation(s)
- Christophe D Proulx
- Department of Pharmacology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3001, 12th Avenue North, Sherbrooke, Quebec, J1H 5N4 Canada
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8
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Yanamala N, Tirupula KC, Klein-Seetharaman J. Preferential binding of allosteric modulators to active and inactive conformational states of metabotropic glutamate receptors. BMC Bioinformatics 2008; 9 Suppl 1:S16. [PMID: 18315847 PMCID: PMC2259417 DOI: 10.1186/1471-2105-9-s1-s16] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Metabotropic glutamate receptors (mGluRs) are G protein coupled receptors that play important roles in synaptic plasticity and other neuro-physiological and pathological processes. Allosteric mGluR ligands are particularly promising drug targets because of their modulatory effects--enhancing or suppressing the response of mGluRs to glutamate. The mechanism by which this modulation occurs is not known. Here, we propose the hypothesis that positive and negative modulators will differentially stabilize the active and inactive conformations of the receptors, respectively. To test this hypothesis, we have generated computational models of the transmembrane regions of different mGluR subtypes in two different conformations. The inactive conformation was modeled using the crystal structure of the inactive, dark state of rhodopsin as template and the active conformation was created based on a recent model of the light-activated state of rhodopsin. Ligands for which the nature of their allosteric effects on mGluRs is experimentally known were docked to the modeled mGluR structures using ArgusLab and Autodock softwares. We find that the allosteric ligand binding pockets of mGluRs are overlapping with the retinal binding pocket of rhodopsin, and that ligands have strong preferences for the active and inactive states depending on their modulatory nature. In 8 out of 14 cases (57%), the negative modulators bound the inactive conformations with significant preference using both docking programs, and 6 out of 9 cases (67%), the positive modulators bound the active conformations. Considering results by the individual programs only, even higher correlations were observed: 12/14 (86%) and 8/9 (89%) for ArgusLab and 10/14 (71%) and 7/9 (78%) for AutoDock. These findings strongly support the hypothesis that mGluR allosteric modulation occurs via stabilization of different conformations analogous to those identified in rhodopsin where they are induced by photochemical isomerization of the retinal ligand--despite the extensive differences in sequences between mGluRs and rhodopsin.
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Affiliation(s)
- Naveena Yanamala
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA.
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9
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Abstract
In this study we report ab initio molecular orbital calculations on the natural hormone angiotensin II, which induces activity at AT1/AT2 receptor subtypes leading to vasoconstriction and subsequent hypertension, and AT2 antagonists. Pharmacophoric features of AT2 antagonists have been studied. A model of AT2 receptor has been made, and angiotensin II as well as antagonists has been systematically docked and their interactions with the receptor analyzed. Calculated ligand-receptor interaction energies have been correlated with experimentally observed biological potency data. Our studies indicate that antagonists retain sufficient interactions to block the receptor but may not be adequate to induce activity at the receptor. A poor antagonist is, therefore, proposed as a close mimic of angiotensin II in terms of interacting with the receptor. These studies further explore the mechanistic aspects of this important class of drugs.
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10
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Modeling binding modes of angiotensin II and pseudopeptide analogues to the AT2 receptor. J Mol Graph Model 2008; 26:991-1003. [DOI: 10.1016/j.jmgm.2007.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2007] [Revised: 08/16/2007] [Accepted: 08/21/2007] [Indexed: 11/17/2022]
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11
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Vodovozova EL. Photoaffinity labeling and its application in structural biology. BIOCHEMISTRY (MOSCOW) 2007; 72:1-20. [PMID: 17309432 DOI: 10.1134/s0006297907010014] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
This review contains a brief consideration of some theoretical aspects of photoaffinity (photoreactive) labeling (PAL), and the most widely used photoreactive groups, such as arylazide, benzophenone, and 3-(trifluoromethyl)-3-phenyldiazirine, are characterized in comparison. Experimental methodology is described, including modern approaches of mass spectrometry for analysis of cross-linking products between the photoreactive probes and biomolecules. Examples of PAL application in diverse fields of structural biology during the last five-ten years are presented. Potential drug targets, transport processes, stereochemistry of interaction of G-protein-coupled receptors with ligands, as well as structural changes in nicotinic acetylcholine receptor are considered. Applications of photoaffinity ganglioside and phospholipid probes for studying biological membranes and of nucleotide probes in investigations of replicative and transcriptional complexes, as well as photoaffinity glycoconjugates for detecting carbohydrate-binding proteins are covered. In combination with modern techniques of instrumental analysis and computer-aided modeling, PAL remains the most important approach in studies on the organization of biological systems.
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Affiliation(s)
- E L Vodovozova
- Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia.
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12
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Nikiforovich GV, Zhang M, Yang Q, Jagadeesh G, Chen HC, Hunyady L, Marshall GR, Catt KJ. Interactions between Conserved Residues in Transmembrane Helices 2 and 7 during Angiotensin AT1Receptor Activation. Chem Biol Drug Des 2006; 68:239-49. [PMID: 17177883 DOI: 10.1111/j.1747-0285.2006.00444.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Site-directed mutagenesis studies and independent molecular modeling studies were combined to investigate the network of inter-residue interactions within the transmembrane region of the angiotensin AT(1a) receptor. Site-directed mutagenesis was focused on residues Tyr292, Asn294, Asn295, and Asn298 in transmembrane helix 7, and the conserved Asp74 in helix 2 and other polar residues. Functional interactions between pairs of residues were evaluated by determining the effects of single and double-reciprocal mutations on agonist-induced AT(1a) receptor activation. Replacement of Tyr292 by aspartate in helix 7 abolished radioligand binding to both Y292D and D74Y/Y292D mutant receptors. Reciprocal mutations of Asp74/Asn294, Ser115/Asn294, Ser252/Asn294, and Asn298/Sen115 caused additive impairment of function, suggesting that these pairs of residues make independent contributions to AT(1a) receptor activation. In contrast, mutations of the Asp74/Tyr298 pair revealed that the D74N/N298D reciprocal mutation substantially increased the impaired inositol phosphate responses of the D74N and N298D receptors. Extensive molecular modeling yielded 3D models of the TM region of the AT(1) receptor and the mutants as well as of their complexes with angiotensin II, which were used to rationalize the possible reasons of impairing of function of some mutants. These data indicate that Asp74 and Asn298 are not optimally positioned for direct strong interaction in the resting conformation of the AT(1a) receptor. Balance of interactions between residues in helix 2 (as D74) and helix 7 (as N294, N295 and N298) in the AT(1) receptors, however, has a crucial role both in determining their functional activity and levels of their expression.
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Affiliation(s)
- Gregory V Nikiforovich
- Department of Biochemistry and Molecular Biophysics, Washington University Medical School, St Louis, MO 63110, USA.
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13
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Baleanu-Gogonea C, Karnik S. Model of the whole rat AT1 receptor and the ligand-binding site. J Mol Model 2006; 12:325-37. [PMID: 16404618 DOI: 10.1007/s00894-005-0049-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Accepted: 07/22/2005] [Indexed: 10/25/2022]
Abstract
We present a three-dimensional model of the rat type 1 receptor (AT1) for the hormone angiotensin II (Ang II). Ang II and the AT1 receptor play a critical role in the cell-signaling process responsible for the actions of renin-angiotensin system in the regulation of blood pressure, water-electrolyte homeostasis and cell growth. Development of improved therapeutics would be significantly enhanced with the availability of a 3D-structure model for the AT1 receptor and of the binding site for agonists and antagonists. This model was constructed using a combination of computation and homology-modeling techniques starting with the experimentally determined three-dimensional structure of bovine rhodopsin (PDB#1F88) as a template. All 359 residues and two disulfide bonds in the rat AT1 receptor have been accounted for in this model. Ramachandran-map analysis and a 1 nanosecond molecular dynamics simulation of the solvated receptor with and without the bound ligand, Ang II, lend credence to the validity of the model. Docking calculations were performed with the agonist, Ang II and the antihypertensive antagonist, losartan. [Figure: see text].
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Affiliation(s)
- Camelia Baleanu-Gogonea
- Department of Molecular Cardiology at Lerner Research Institute, The Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA
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14
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Georgsson J, Sköld C, Plouffe B, Lindeberg G, Botros M, Larhed M, Nyberg F, Gallo-Payet N, Gogoll A, Karlén A, Hallberg A. Angiotensin II pseudopeptides containing 1,3,5-trisubstituted benzene scaffolds with high AT2 receptor affinity. J Med Chem 2005; 48:6620-31. [PMID: 16220978 DOI: 10.1021/jm050280z] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two 1,3,5-trisubstituted aromatic scaffolds intended to serve as gamma-turn mimetics have been synthesized and incorporated in five pseudopeptide analogues of angiotensin II (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe), replacing Val-Tyr-Ile, Val-Tyr, or Tyr-Ile. All the tested compounds exhibited nanomolar affinity for the AT2 receptor with the best compound (3) having a K(i) of 1.85 nM. Four pseudopeptides were AT2 selective, while one (5) also exhibited good affinity for the AT1 receptor (K(i) = 30.3 nM). This pseudopeptide exerted full agonistic activity in an AT2 receptor induced neurite outgrowth assay but displayed no agonistic effect in an AT1 receptor functional assay. Molecular modeling, using the program DISCOtech, showed that the high-affinity ligands could interact similarly with the AT2 receptor as other ligands with high affinity for this receptor. A tentative agonist model is proposed for AT2 receptor activation by angiotensin II analogues. We conclude that the 1,3,5-trisubstituted benzene rings can be conveniently prepared and are suitable as gamma-turn mimics.
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MESH Headings
- Angiotensin II/analogs & derivatives
- Angiotensin II/chemical synthesis
- Angiotensin II/pharmacology
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/physiology
- Benzene Derivatives/chemical synthesis
- Benzene Derivatives/pharmacology
- Cell Line, Tumor
- Female
- In Vitro Techniques
- Ligands
- Liver/metabolism
- Models, Molecular
- Molecular Mimicry
- Muscle Contraction/drug effects
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/physiology
- Myometrium/metabolism
- Neurites/drug effects
- Neurites/physiology
- Oligopeptides/chemical synthesis
- Oligopeptides/pharmacology
- Protein Structure, Secondary
- Rabbits
- Radioligand Assay
- Rats
- Receptor, Angiotensin, Type 1/agonists
- Receptor, Angiotensin, Type 1/metabolism
- Receptor, Angiotensin, Type 2/agonists
- Receptor, Angiotensin, Type 2/metabolism
- Swine
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Affiliation(s)
- Jennie Georgsson
- Department of Medicinal Chemistry, Division of Organic Pharmaceutical Chemistry, Uppsala University, P.O. Box 574, SE-751 23 Uppsala, Sweden
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15
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Rosenström U, Sköld C, Plouffe B, Beaudry H, Lindeberg G, Botros M, Nyberg F, Wolf G, Karlén A, Gallo-Payet N, Hallberg A. New selective AT2 receptor ligands encompassing a gamma-turn mimetic replacing the amino acid residues 4-5 of angiotensin II act as agonists. J Med Chem 2005; 48:4009-24. [PMID: 15943474 DOI: 10.1021/jm0491492] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
New benzodiazepine-based gamma-turn mimetics with one or two amino acid side chains were synthesized. The gamma-turn mimetics were incorporated into angiotensin II (Ang II) replacing the Val(3)-Tyr(4)-Ile(5) or Tyr(4)-Ile(5) peptide segments. All of the resulting pseudopeptides displayed high AT(2)/AT(1) receptor selectivity and exhibited AT(2) receptor affinity in the low nanomolar range. Molecular modeling was used to investigate whether the compounds binding to the AT(2) receptor could position important structural elements in common areas. A previously described benzodiazepine-based gamma-turn mimetic with high affinity for the AT(2) receptor was also included in the modeling. It was found that the molecules, although being structurally quite different, could adopt the same binding mode/interaction pattern in agreement with the model hypothesis. The pseudopeptides selected for agonist studies were shown to act as AT(2) receptor agonists being able to induce outgrowth of neurite cells, stimulate p42/p44(mapk), and suppress proliferation of PC12 cells.
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16
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Johannesson P, Erdélyi M, Lindeberg G, Frändberg PA, Nyberg F, Karlén A, Hallberg A. AT2-selective angiotensin II analogues containing tyrosine-functionalized 5,5-bicyclic thiazabicycloalkane dipeptide mimetics. J Med Chem 2005; 47:6009-19. [PMID: 15537355 DOI: 10.1021/jm049651m] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper reports the synthesis of two angiotensin II analogues with tyrosine-functionalized 5,5-bicyclic thiazabicycloalkane dipeptide mimetics replacing the Tyr(4)-Ile(5) residues. The preparation of these analogues relies on the synthesis and incorporation of an alpha,alpha-disubstituted chimeric amino acid derivative and on-resin bicyclization to a cysteine residue. The synthesized analogues both displayed high angiotensin AT(2)/AT(1) receptor binding preferences and had AT(2) receptor affinities in the same low nanomolar range as angiotensin II itself. Conformational analysis, using experimental constraints derived from NMR studies, indicated that the Tyr(4) and His(6) residues in one of the angiotensin II analogues were in close proximity to each other.
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Affiliation(s)
- Petra Johannesson
- Department of Medicinal Chemistry, Uppsala University, BMC, Box 574, SE-751 23 Uppsala, Sweden
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17
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Pulakat L, Mandavia CH, Gavini N. Role of Phe308 in the seventh transmembrane domain of the AT2 receptor in ligand binding and signaling. Biochem Biophys Res Commun 2004; 319:1138-43. [PMID: 15194486 DOI: 10.1016/j.bbrc.2004.05.092] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2004] [Indexed: 11/28/2022]
Abstract
Studies on Angiotensin II (Ang II) receptor type AT1 have suggested that interaction between the two highly conserved residues, Tyr292 in the 7th transmembrane domain (TMD) and the Asp74 in the 2nd TMD, is critical for linking the Ang II binding and AT1 receptor-Gq protein coupling. In the Ang II receptor type AT2, the Asp is conserved (Asp90 in 2nd TMD), however, there is no Tyr residue in the 7th TMD and Phe308 occupies the analogous position to Tyr292 of the AT1. Replacing this Phe308 with Ala reduced receptor affinity to peptidic ligands (125)I-Ang II (K(d) = 0.37 nM) and (125)I-CGP42112A (K(d) = 0.56 nM), but retained the ability of the AT2 to reduce cGMP levels in Xenopus oocytes. Thus, the Phe308 of the AT2 does not mimic the role of Tyr292 of the AT1 in the receptor activation upon Ang II binding. We have also shown that the M8 mutant of the AT2 with the 7th TMD similar to that of wild type AT2 can couple to PLC like the AT1 and bind the AT2-specific ligands with high affinity. Since the Ang II is shown to bind to both the AT1 and the AT2 in an identical manner, we propose that the absence of Tyr in the 7th TMD of the AT2 does not prevent the receptor from coupling to Gq-protein, rather may contribute to the freedom of the AT2 to couple to trimeric G-proteins in both G- betagamma dependent and independent manners upon Ang II binding.
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Affiliation(s)
- Lakshmi Pulakat
- Department of Biological Sciences, Bowling Green State University, Bowling Green, OH 43403, USA.
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18
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Rosenström U, Sköld C, Lindeberg G, Botros M, Nyberg F, Karlén A, Hallberg A. A selective AT2 receptor ligand with a gamma-turn-like mimetic replacing the amino acid residues 4-5 of angiotensin II. J Med Chem 2004; 47:859-70. [PMID: 14761188 DOI: 10.1021/jm030921v] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Three angiotensin II (Ang II) analogues encompassing a benzodiazepine-based gamma-turn-like scaffold have been synthesized. Evaluation of the compounds in a radioligand binding assay showed that they had no affinity to the rat liver AT(1) receptor. However, one of the compounds displayed considerable affinity to the pig uterus AT(2) receptor (K(i) = 3.0 nM) while the other two lacked affinity to this receptor. It was hypothesized that the reason for the inactivity of one of these analogues to the AT(2) receptor was that the guanidino group of the Arg(2) residue and/or the N-terminal end of the pseudopeptide could not interact optimally with the receptor. To investigate this hypothesis, a conformational analysis was performed and a comparison was carried out with the monocyclic methylenedithioether analogue cyclo(S-CH(2)-S)[Cys(3,5)]Ang II which is known to bind with high affinity to the AT(2) receptor (K(i) = 0.62 nM). This comparison showed that, in the compounds with high AT(2) receptor affinity, the guanidino group of the Arg(2) residue and the N-terminal end could access common regions of space that were not accessible to the inactive compound. To examine the importance of the guanidino group for binding, the Arg side chain was removed by substituting Arg(2) for Ala(2) in the analogue having the high affinity. This analogue lacked affinity to AT(2) receptors, which supports the role of the guanidino group in receptor binding.
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Affiliation(s)
- Ulrika Rosenström
- Division of Organic Pharmaceutical Chemistry, Department of Medicinal Chemistry, BMC, Box 574, Uppsala University, SE-751 23 Uppsala, Sweden
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19
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Gaudreau R, Beaulieu ME, Chen Z, Le Gouill C, Lavigne P, Stanková J, Rola-Pleszczynski M. Structural determinants regulating expression of the high affinity leukotriene B4 receptor: involvement of dileucine motifs and alpha-helix VIII. J Biol Chem 2003; 279:10338-45. [PMID: 14688279 DOI: 10.1074/jbc.m309207200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutational analysis of determinants located in the C-terminal (C) tail of the high affinity leukotriene (LT) B(4) receptor, BLT1, was performed to assess their significance in BLT1 trafficking. When expressed in COS-7 cells, a BLT1 deletion mutant lacking the C-tail (G291stop) displayed higher numbers of binding sites and increased signal transduction compared with wild-type (WT) BLT1. Addition of the C-tail from either the platelet-activating factor receptor or the LTD(4) receptor, CysLT1, did not restore WT phenotype. Moreover, the number of LTB(4) binding sites was higher in the chimeras than in the WT BLT1, suggesting the requirement for specific structural determinants within the BLT1 C-tail. Elimination of a distal C-tail dileucine motif (Leu(304)-Leu(305)), but not the proximal (Leu(292)-Leu(293)) motif, altered BLT1 pharmacological characteristics and caused a moderate constitutive receptor activation. Surprisingly, all mutant receptors were efficiently delivered to the plasma membrane, but not to a greater extent than WT BLT1, as assessed by flow cytometry. Furthermore, substitution of Leu(304)-Leu(305) prevented LTB(4)-induced BLT1 internalization. Molecular modeling of BLT1 on the bovine rhodopsin receptor scaffold strongly suggested the involvement of the distal dileucine motif (Leu(304)-Leu(305)) in a hydrophobic core, including intrahelical interactions within alpha-helix VIII and interhelical interactions with residues of helix I. Disruption of this hydrophobic core is proposed to increase the population of receptors in the active form, to restrain their trafficking and to facilitate the activation of BLT1 as indicated by the increased maximal level of binding of the ligand and constitutive activation of the receptor.
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Affiliation(s)
- Rémi Gaudreau
- Immunology Division, Department of Pediatrics, Faculty of Medicine, Université de Sherbrooke, Quebec J1H 5N4, Canada
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20
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Lindman S, Lindeberg G, Frändberg PA, Nyberg F, Karlén A, Hallberg A. Effect of 3-5 monocyclizations of angiotensin II and 4-aminoPhe6-Ang II on AT2 receptor affinity. Bioorg Med Chem 2003; 11:2947-54. [PMID: 12788364 DOI: 10.1016/s0968-0896(03)00212-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The endogenous angiotensin II (Ang II) and the synthetic AT(2) selective agonist 4-aminoPhe(6)-Ang II respond very differently to identical cyclizations. Cyclizations of Ang II by thioacetalization, involving the 3 and 5 amino acid residue side chains, provided ligands with almost equipotent binding affinities to Ang II at the AT(2) receptor. In contrast, the same cyclization procedures applied on the AT(2) selective 4-aminoPhe(6)-Ang II delivered significantly less potent AT(2) receptor ligands, although the AT(2)/AT(1) selectivity was still very high. The fact that different structure-activity relationships are observed after imposing conformational restrictions on Ang II and 4-aminoPhe(6)-Ang II, respectively, suggests that the peptides, despite large similarities might adopt quite different backbone conformations when binding to the AT(2) receptor.
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Affiliation(s)
- Susanna Lindman
- Department of Organic Pharmaceutical Chemistry, Uppsala Biomedical Centre, Uppsala University, Box 574, SE-751 23 Uppsala, Sweden
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D'Amelio N, Gaggelli E, Gaggelli N, Mancini F, Molteni E, Valensin D, Valensin G. The structure of the Ce(III)-angiotensin II complex as obtained from NMR data and molecular dynamics calculations. J Inorg Biochem 2003; 95:225-9. [PMID: 12763668 DOI: 10.1016/s0162-0134(03)00098-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Angiotensin II is shown by nuclear magnetic resonance (NMR) to form a complex in water at pH 4.0 with cerium(III), the ideal paramagnetic probe for Ca(2+). Paramagnetic shifts induced by the metal were used for the determination of dissociation constant and complex stoichiometry. ROESY cross-peaks and 3 J(HN-H)(alpha) coupling constants were converted into distance and angular constraints to determine the structure of the complex by molecular dynamics using the simulated annealing protocol. The complex is kinetically labile and involves the Asp-1 side chain and the Phe-8 terminal carboxylates as binding groups resembling a hairpin which has been suggested as a possible biologically active structure.
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Affiliation(s)
- Nicola D'Amelio
- Department of Chemistry and the NMR Center, University of Siena, Via Aldo Moro, 53100 Siena, Italy
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Boucard AA, Sauvé SS, Guillemette G, Escher E, Leduc R. Photolabelling the rat urotensin II/GPR14 receptor identifies a ligand-binding site in the fourth transmembrane domain. Biochem J 2003; 370:829-38. [PMID: 12495432 PMCID: PMC1223243 DOI: 10.1042/bj20021566] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2002] [Revised: 12/02/2002] [Accepted: 12/20/2002] [Indexed: 11/17/2022]
Abstract
A urotensin II (U-II) peptide analogue containing the photoreactive p -benzoyl-L-phenylalanine (Bz-Phe) in the sixth position was used to identify ligand-binding sites of the rat U-II receptor, also known as GPR14. [Bz-Phe(6)]U-II bound the receptor expressed in COS-7 cells with high affinity (IC(50) 0.7 nM) and was as potent as U-II in the agonist-induced production of inositol phosphate. Photolabelling of the U-II receptor with (125)I-[Bz-Phe(6)]U-II resulted in the specific formation of a glycosylated (125)I-[Bz-Phe(6)]U-II-U-II receptor complex of 60 kDa. Digestion of the 60 kDa complex with endoproteinase Glu-C generated a fragment of 17 kDa circumscribing the labelled fragment to residues 148-286. Digestion of the ligand-receptor complex with endoproteinase Arg-C produced a short peptide of 4 kDa corresponding to fragments 125-148, 167-192 or 210-233. CNBr treatment of the endoproteinase-Glu-C and -Arg-C fragments yielded 2 kDa fragments, defining the labelling site to methionine residues 184/185 of the fourth transmembrane domain. Photolabelling of two mutant receptors, M184L/M185L and M184A/M185A, led to a significant decrease in the overall yield of covalent labelling. Taken together, our results indicate that position 6 of U-II normally occupied by phenylalanine would interact with Met(184) and/or Met(185) of the fourth transmembrane domain of the U-II receptor. This information should be of significant value in the study of the interactions between U-II and its cognate receptor.
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Affiliation(s)
- Antony A Boucard
- Department of Pharmacology, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4
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Pérodin J, Deraët M, Auger-Messier M, Boucard AA, Rihakova L, Beaulieu ME, Lavigne P, Parent JL, Guillemette G, Leduc R, Escher E. Residues 293 and 294 are ligand contact points of the human angiotensin type 1 receptor. Biochemistry 2002; 41:14348-56. [PMID: 12450401 DOI: 10.1021/bi0258602] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The human angiotensin II type 1 receptor (hAT(1)) was photolabeled with a high-affinity radiolabeled photoreactive analogue of AngII, (125)I-[Sar(1), Val(5), p-Benzoyl-L-phenylalanine(8)]AngII ((125)I-[Sar(1),Bpa(8)]AngII). Chemical cleavage with CNBr produced a 7 kDa fragment (285-334) of the C-terminal portion of the hAT(1). Manual Edman radiosequencing of photolabeled, per-acetylated, and CNBr-fragmented receptor showed that ligand incorporation occurred through Phe(293) and Asn(294) within the seventh transmembrane domain of the hAT(1). Receptor mutants with Met introduced at the presumed contact residues, F293M and N294M, were photolabeled and then digested with CNBr. SDS-PAGE analysis of those digested mutant receptors confirmed the contact positions 293 and 294 through ligand release induced by CNBr digestion. Additional receptor mutants with Met residues introduced into the N- and C-terminal proximity of those residues 293 and 294 of the hAT(1) produced, upon photolabeling and CNBr digestion, fragmentation patterns compatible only with the above contact residues. These data indicate that the C-terminal residue of AngII interacts with residues 293 and 294 of the seventh transmembrane domain of the human AT(1) receptor. Taking into account a second receptor-ligand contact at the second extracellular loop and residue 3 of AngII (Boucard, A. A., Wilkes, B. C., Laporte, S. A., Escher, E., Guillemette, G., and Leduc, R. (2000) Biochemistry 39, 9662-70) the Ang II molecule must adopt an extended structure in the AngII binding pocket.
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Affiliation(s)
- Jacqueline Pérodin
- Département de pharmacologie, Faculté de médecine, Université de Sherbrooke, 3001 12e Avenue Nord, Sherbrooke, Québec, J1H 5N4, Canada
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24
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Rihakova L, Deraët M, Auger-Messier M, Pérodin J, Boucard AA, Guillemette G, Leduc R, Lavigne P, Escher E. Methionine proximity assay, a novel method for exploring peptide ligand-receptor interaction. J Recept Signal Transduct Res 2002; 22:297-313. [PMID: 12503623 DOI: 10.1081/rrs-120014603] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Probing G-protein coupled receptor (GPCR) structures is a priority in the functional and structural understanding of GPCRs. In the past, we have used several approaches around photoaffinity labeling in order to establish contact points between peptide ligands and their cognate receptors. Such contact points are helpful to build reality based molecular models of GPCRs and to elucidate their activation mechanisms. Most studies of peptidergic GPCRs have been done with photolabeling peptides containing the benzophenone moiety as a reputedly non-selective probe. However our recent results are now showing that p-benzoylphenylalanine (Bpa) has some selectivity for Met residues in the receptor protein, reducing the accuracy of this method. Turning a problem into an asset, modified analogues of Bpa, e.g. p,p'-nitrobenzoylphenylalanine (NO2Bpa), display increased selectivity for such Met residues. It means a photoprobe containing such modified benzophenone-moieties does not label a receptor protein unless a Met residue is in the immediate vicinity. This unique property allows us to propose and show the feasibility and utility of a new method for scanning the contact areas of peptidergic GPCRs, the Methionine Proximity Assay (MPA). Putative contact residues of the receptor are exchanged to Met residues by site-directed mutagenesis and are subjected to photoaffinity labeling with such modified benzophenone-containing peptides. Successful incorporation indicates physical proximity of those residues. This principle is established and explored with benzophenone-containing analogues of angiotensin II and the two known human angiotensin II receptors AT1 and AT2, determining contact points in both receptors. This approach has several important advantages over other scanning approaches, e.g., the SCAM procedure, since the MPA-method can be used in the hydrophobic core of receptors.
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Affiliation(s)
- Lenka Rihakova
- Department of Pharmacology, Faculty of Medicine, University of Sherbrooke, 3001 12th Ave. N, Sherbrooke, QC JIH 5N4, Canada
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