1
|
Cheng Y, Hyodo T, Yamaguchi K, Ohwada T, Otani Y. Complete amide cis- trans switching synchronized with disulfide bond formation and cleavage in a proline-mimicking system. Chem Commun (Camb) 2024; 60:6158-6161. [PMID: 38804552 DOI: 10.1039/d4cc01096e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
A typical naturally occurring disulfide structure in proteins is an 8-membered disulfide ring formed between two adjacent cysteine (Cys-Cys) residues. Based on this structure, we designed 7- to 9-membered disulfide ring molecules, embedded in the 7-azabicyclo[2.2.1]heptane skeleton, that switch their conformation from exclusively trans-amide to exclusively cis-amide upon redox transformation from dithiol to disulfide, and vice versa. Constrained shape of disulfide rings is rare in nature, and the present molecular structure is expected to be a useful fundamental component for the construction of new conformation-switching systems.
Collapse
Affiliation(s)
- Yuhe Cheng
- Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
| | - Tadashi Hyodo
- School of Pharmaceutical Sciences at Kagawa Campus, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa 769-2193, Japan
| | - Kentaro Yamaguchi
- School of Pharmaceutical Sciences at Kagawa Campus, Tokushima Bunri University, 1314-1 Shido, Sanuki, Kagawa 769-2193, Japan
| | - Tomohiko Ohwada
- Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
| | - Yuko Otani
- Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
| |
Collapse
|
2
|
He ZC, Zhang T, Peng W, Mei Q, Wang QZ, Ding F. Exploring the neurotoxicity of chiral dinotefuran towards nicotinic acetylcholine receptors: Enantioselective insights into species selectivity. JOURNAL OF HAZARDOUS MATERIALS 2024; 469:134020. [PMID: 38521037 DOI: 10.1016/j.jhazmat.2024.134020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 03/11/2024] [Accepted: 03/11/2024] [Indexed: 03/25/2024]
Abstract
Dinotefuran is a chiral neonicotinoid that is widely distributed in environmental matrices, but its health risks to different organisms are poorly understood. This study investigated the neurotoxic responses of honeybee/cotton aphid nicotinic acetylcholine receptors (nAChRs) to chiral dinotefuran at the enantiomeric scale and demonstrated the microscopic mechanism of species selectivity in nAChR-mediated enantioselective neurotoxicity. The findings indicated that (S)-dinotefuran had a higher affinity for honeybee nAChR than (R)-dinotefuran whereas both enantiomers exhibited similar bioactivity toward cotton aphid nAChR. The results of dynamic neurotoxic processes indicated the association of conformational changes induced by chiral dinotefuran with its macroscopic neurotoxicity, and (R)-dinotefuran, which exhibit low toxicity to honeybee, was found to induce significant conformational changes in the enantioselective neurotoxic reaction, as supported by the average root-mean-square fluctuation (0.35 nm). Energy decomposition results indicated that electrostatic contribution (ΔGele) is the critical energy term that leads to substantial enantioselectivity, and both Trp-51 (-2.57 kcal mol-1) and Arg-75 (-4.86 kcal mol-1), which form a hydrogen-bond network, are crucial residues in mediating the species selectivity for enantioselective neurotoxic responses. Clearly, this study provides experimental evidence for a comprehensive assessment of the health hazards of chiral dinotefuran.
Collapse
Affiliation(s)
- Zhi-Cong He
- School of Water and Environment, Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education, Key Laboratory of Ecohydrology and Water Security in Arid and Semi-Arid Regions of Ministry of Water Resources, Chang'an University, Xi'an 710054, China
| | - Tao Zhang
- School of Water and Environment, Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education, Key Laboratory of Ecohydrology and Water Security in Arid and Semi-Arid Regions of Ministry of Water Resources, Chang'an University, Xi'an 710054, China
| | - Wei Peng
- State Key Laboratory of Loess and Quaternary Geology, Center for Excellence in Quaternary Science and Global Change, Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710061, China; State Key Laboratory of Physical Chemistry of Solid Surfaces, Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
| | - Qiong Mei
- School of Water and Environment, Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education, Key Laboratory of Ecohydrology and Water Security in Arid and Semi-Arid Regions of Ministry of Water Resources, Chang'an University, Xi'an 710054, China; School of Land Engineering, Chang'an University, Xi'an 710054, China
| | - Qi-Zhao Wang
- School of Water and Environment, Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education, Key Laboratory of Ecohydrology and Water Security in Arid and Semi-Arid Regions of Ministry of Water Resources, Chang'an University, Xi'an 710054, China
| | - Fei Ding
- School of Water and Environment, Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of Ministry of Education, Key Laboratory of Ecohydrology and Water Security in Arid and Semi-Arid Regions of Ministry of Water Resources, Chang'an University, Xi'an 710054, China.
| |
Collapse
|
3
|
Chrestia JF, Turani O, Araujo NR, Hernando G, Esandi MDC, Bouzat C. Regulation of nicotinic acetylcholine receptors by post-translational modifications. Pharmacol Res 2023; 190:106712. [PMID: 36863428 DOI: 10.1016/j.phrs.2023.106712] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 02/21/2023] [Accepted: 02/24/2023] [Indexed: 03/04/2023]
Abstract
Nicotinic acetylcholine receptors (nAChRs) comprise a family of pentameric ligand-gated ion channels widely distributed in the central and peripheric nervous system and in non-neuronal cells. nAChRs are involved in chemical synapses and are key actors in vital physiological processes throughout the animal kingdom. They mediate skeletal muscle contraction, autonomic responses, contribute to cognitive processes, and regulate behaviors. Dysregulation of nAChRs is associated with neurological, neurodegenerative, inflammatory and motor disorders. In spite of the great advances in the elucidation of nAChR structure and function, our knowledge about the impact of post-translational modifications (PTMs) on nAChR functional activity and cholinergic signaling has lagged behind. PTMs occur at different steps of protein life cycle, modulating in time and space protein folding, localization, function, and protein-protein interactions, and allow fine-tuned responses to changes in the environment. A large body of evidence demonstrates that PTMs regulate all levels of nAChR life cycle, with key roles in receptor expression, membrane stability and function. However, our knowledge is still limited, restricted to a few PTMs, and many important aspects remain largely unknown. There is thus a long way to go to decipher the association of aberrant PTMs with disorders of cholinergic signaling and to target PTM regulation for novel therapeutic interventions. In this review we provide a comprehensive overview of what is known about how different PTMs regulate nAChR.
Collapse
Affiliation(s)
- Juan Facundo Chrestia
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Ornella Turani
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Noelia Rodriguez Araujo
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Guillermina Hernando
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - María Del Carmen Esandi
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina
| | - Cecilia Bouzat
- Instituto de Investigaciones Bioquímicas de Bahía Blanca, Departamento de Biología, Bioquímica y Farmacia, Universidad Nacional del Sur-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Bahía Blanca 8000, Argentina.
| |
Collapse
|
4
|
Bartoccini F, Retini M, Crinelli R, Menotta M, Fraternale A, Piersanti G. Dithiol Based on l-Cysteine and Cysteamine as a Disulfide-Reducing Agent. J Org Chem 2022; 87:10073-10079. [PMID: 35862282 PMCID: PMC9361291 DOI: 10.1021/acs.joc.2c01050] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
We report the synthesis, chemical properties, and disulfide
bond-reducing
performance of a dithiol called NACMEAA, conceived as a hybrid of
two biologically relevant thiols: cysteine and cysteamine. NACMEAA
is conveniently prepared from inexpensive l-cystine in an
efficient manner. As a nonvolatile, highly soluble, and neutral compound
at physiological pH with the first thiol pKa value of 8.0, NACMEAA is reactive and user-friendly. We also demonstrate
that NACMEAA reduces disulfide bonds in GSSG and lysozyme.
Collapse
Affiliation(s)
- Francesca Bartoccini
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Piazza Rinascimento 6, 61029 Urbino, PU, Italy
| | - Michele Retini
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Piazza Rinascimento 6, 61029 Urbino, PU, Italy
| | - Rita Crinelli
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Piazza Rinascimento 6, 61029 Urbino, PU, Italy
| | - Michele Menotta
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Piazza Rinascimento 6, 61029 Urbino, PU, Italy
| | - Alessandra Fraternale
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Piazza Rinascimento 6, 61029 Urbino, PU, Italy
| | - Giovanni Piersanti
- Department of Biomolecular Sciences, University of Urbino Carlo Bo, Piazza Rinascimento 6, 61029 Urbino, PU, Italy
| |
Collapse
|
5
|
Conformational transitions and ligand-binding to a muscle-type nicotinic acetylcholine receptor. Neuron 2022; 110:1358-1370.e5. [PMID: 35139364 DOI: 10.1016/j.neuron.2022.01.013] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 11/02/2021] [Accepted: 01/10/2022] [Indexed: 12/15/2022]
Abstract
Fast synaptic communication requires receptors that respond to the presence of neurotransmitter by opening an ion channel across the post-synaptic membrane. The muscle-type nicotinic acetylcholine receptor from the electric fish, Torpedo, is the prototypic ligand-gated ion channel, yet the structural changes underlying channel activation remain undefined. Here we use cryo-EM to solve apo and agonist-bound structures of the Torpedo nicotinic receptor embedded in a lipid nanodisc. Using both a direct biochemical assay to define the conformational landscape and molecular dynamics simulations to assay flux through the pore, we correlate structures with functional states and elucidate the motions that lead to pore activation of a heteromeric nicotinic receptor. We highlight an underappreciated role for the complementary subunit in channel gating, establish the structural basis for the differential agonist affinities of α/δ versus α /γ sites, and explain why nicotine is less potent at muscle nicotinic receptors compared to neuronal ones.
Collapse
|
6
|
Interactions of Nereistoxin and Its Analogs with Vertebrate Nicotinic Acetylcholine Receptors and Molluscan ACh Binding Proteins. Mar Drugs 2022; 20:md20010049. [PMID: 35049904 PMCID: PMC8777805 DOI: 10.3390/md20010049] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/09/2021] [Accepted: 12/14/2021] [Indexed: 02/04/2023] Open
Abstract
Nereistoxin (NTX) is a marine toxin isolated from an annelid worm that lives along the coasts of Japan. Its insecticidal properties were discovered decades ago and this stimulated the development of a variety of insecticides such as Cartap that are readily transformed into NTX. One unusual feature of NTX is that it is a small cyclic molecule that contains a disulfide bond. In spite of its size, it acts as an antagonist at insect and mammalian nicotinic acetylcholine receptors (nAChRs). The functional importance of the disulfide bond was assessed by determining the effects of inserting a methylene group between the two sulfur atoms, creating dimethylaminodithiane (DMA-DT). We also assessed the effect of methylating the NTX and DMA-DT dimethylamino groups on binding to three vertebrate nAChRs. Radioligand receptor binding experiments were carried out using washed membranes from rat brain and fish (Torpedo) electric organ; [3H]-cytisine displacement was used to assess binding to the predominantly high affinity alpha4beta2 nAChRs and [125I]-alpha-bungarotoxin displacement was used to measure binding of NTX and analogs to the alpha7 and skeletal muscle type nAChRs. While the two quaternary nitrogen analogs, relative to their respective tertiary amines, displayed lower α4β2 nAChR binding affinities, both displayed much higher affinities for the Torpedo muscle nAChR and rat alpha7 brain receptors than their respective tertiary amine forms. The binding affinities of DMA-DT for the three nAChRs were lower than those of NTX and MeNTX. An AChBP mutant lacking the C loop disulfide bond that would potentially react with the NTX disulfide bond displayed an NTX affinity very similar to the parent AChBP. Inhibition of [3H]-epibatidine binding to the AChBPs was not affected by exposure to NTX or MeNTX for up to 24 hr prior to addition of the radioligand. Thus, the disulfide bond of NTX is not required to react with the vicinal disulfide in the AChBP C loop for inhibition of [3H]-epibatidine binding. However, a reversible disulfide interchange reaction of NTX with nAChRs might still occur, especially under reducing conditions. Labeled MeNTX, because it can be readily prepared with high specific radioactivity and possesses relatively high affinity for the nAChR-rich Torpedo nAChR, would be a useful probe to detect and identify any nereistoxin adducts.
Collapse
|
7
|
Tillman TS, Choi Z, Xu Y, Tang P. Functional Tolerance to Cysteine Mutations in Human α7 Nicotinic Acetylcholine Receptors. ACS Chem Neurosci 2020; 11:242-247. [PMID: 31951367 DOI: 10.1021/acschemneuro.9b00647] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor (α7 nAChR) is involved in various intracellular signaling pathways that mediate addiction, chronic pain, and other diseases, but its intracellular domain structures remain undetermined. The presence of 17 native cysteines in α7 nAChR provides opportunities for extracting structural information through site-directed labeling of chemical probes in strategic locations, but it also creates uncertainties in channel function when those native cysteines must be mutated. Using site-directed mutagenesis and two-electrode voltage clamp electrophysiology measurements, we found that α7 nAChR's function was well tolerated for mutations of all 13 cysteines as long as two pairs of disulfide-bond cysteines remained in the extracellular domain. Furthermore, surface plasmon resonance measurements showed that the cysteine mutations did not affect α7 nAChR binding to the intracellular protein PICK1. The study suggests that a high native cysteine content does not necessarily preclude the use of single cysteine labeling for acquiring structural information on functional proteins.
Collapse
Affiliation(s)
- Tommy S. Tillman
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Zachary Choi
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Yan Xu
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Structural Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Pei Tang
- Department of Anesthesiology and Perioperative Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Computational and Systems Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| |
Collapse
|
8
|
Sereikaitė V, Jensen TMT, Bartling CRO, Jemth P, Pless SA, Strømgaard K. Probing Backbone Hydrogen Bonds in Proteins by Amide-to-Ester Mutations. Chembiochem 2018; 19:2136-2145. [PMID: 30073762 DOI: 10.1002/cbic.201800350] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Indexed: 01/09/2023]
Abstract
All proteins contain characteristic backbones formed of consecutive amide bonds, which can engage in hydrogen bonds. However, the importance of these is not easily addressed by conventional technologies that only allow for side-chain substitutions. By contrast, technologies such as nonsense suppression mutagenesis and protein ligation allow for manipulation of the protein backbone. In particular, replacing the backbone amide groups with ester groups, that is, amide-to-ester mutations, is a powerful tool to examine backbone-mediated hydrogen bonds. In this minireview, we showcase examples of how amide-to-ester mutations can be used to uncover pivotal roles of backbone-mediated hydrogen bonds in protein recognition, folding, function, and structure.
Collapse
Affiliation(s)
- Vita Sereikaitė
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2200, Copenhagen, Denmark
| | - Thomas M T Jensen
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2200, Copenhagen, Denmark
| | - Christian R O Bartling
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2200, Copenhagen, Denmark
| | - Per Jemth
- Department of Medical Biochemistry and Microbiology, Uppsala University, BMC, Box 582, 75123, Uppsala, Sweden
| | - Stephan A Pless
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2200, Copenhagen, Denmark
| | - Kristian Strømgaard
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2200, Copenhagen, Denmark
| |
Collapse
|
9
|
Richardson JS, Videau LL, Williams CJ, Richardson DC. Broad Analysis of Vicinal Disulfides: Occurrences, Conformations with Cis or with Trans Peptides, and Functional Roles Including Sugar Binding. J Mol Biol 2017; 429:1321-1335. [PMID: 28336403 DOI: 10.1016/j.jmb.2017.03.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 03/12/2017] [Accepted: 03/13/2017] [Indexed: 10/19/2022]
Abstract
Vicinal disulfides between sequence-adjacent cysteine residues are very rare and rather startling structural features which play a variety of functional roles. Typically discussed as an isolated curiosity, they have never received a general treatment covering both cis and trans forms. Enabled by the growing database of high-resolution structures, required deposition of diffraction data, and improved methods for discriminating reliable from dubious cases, we identify and describe distinct protein families with reliably genuine examples of cis or trans vicinal disulfides and discuss their conformations, conservation, and functions. No cis-trans interconversions and only one case of catalytic redox function are seen. Some vicinal disulfides are essential to large, functionally coupled motions, whereas most form the centers of tightly packed internal regions. Their most widespread biological role is providing a rigid hydrophobic contact surface under the undecorated side of a sugar or multiring ligand, contributing an important aspect of binding specificity.
Collapse
Affiliation(s)
- Jane S Richardson
- Department of Biochemistry, 3711 Duke University Medical Center, Durham, NC 27710, USA.
| | - Lizbeth L Videau
- Department of Biochemistry, 3711 Duke University Medical Center, Durham, NC 27710, USA
| | | | - David C Richardson
- Department of Biochemistry, 3711 Duke University Medical Center, Durham, NC 27710, USA
| |
Collapse
|
10
|
Thompson AJ, Metzger S, Lochner M, Ruepp MD. The binding orientation of epibatidine at α7 nACh receptors. Neuropharmacology 2017; 116:421-428. [PMID: 28089847 PMCID: PMC5390772 DOI: 10.1016/j.neuropharm.2017.01.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 01/09/2017] [Accepted: 01/11/2017] [Indexed: 11/30/2022]
Abstract
Epibatidine is an alkaloid toxin that binds with high affinity to nicotinic and muscarinic acetylcholine receptors, and has been extensively used as a research tool. To examine binding interactions at the nicotinic receptor, it has been co-crystallised with the structural homologue acetylcholine binding protein (AChBP; PDB ID 2BYQ), and with an AChBP chimaera (3SQ6) that shares 64% sequence identity with the α7 nACh receptor. However, the binding orientations revealed by AChBP co-crystal structures may not precisely represent their receptor homologues and experimental evidence is needed to verify the ligand poses. Here we identify potential binding site interactions between epibatidine and AChBP residues, and substitute equivalent positions in the α7 nACh receptor. The effects of these are probed by [3H]epibatidine binding following the expression α7 nACh receptor cysteine mutants in HEK 293 cells. Of the sixteen mutants created, the affinity of epibatidine was unaffected by the substitutions Q55C, L106C, L116C, T146C, D160C and S162C, reduced by C186A and C187A, increased by Q114C and S144C, and abolished by W53C, Y91C, N104C, W145C, Y184C and Y191C. These results are consistent with the predicted orientations in AChBP and suggest that epibatidine is likely to occupy a similar location at α7 nACh receptors. We speculate that steric constraints placed upon the C-5 position of the pyridine ring in 3SQ6 may account for the relatively poor affinities of epibatidine derivatives that are substituted at this position.
Collapse
Affiliation(s)
| | - Simon Metzger
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Martin Lochner
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland; Institute of Biochemistry and Molecular Medicine, University of Bern, Bern, Switzerland
| | - Marc-David Ruepp
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland.
| |
Collapse
|
11
|
Brust A, Croker DE, Colless B, Ragnarsson L, Andersson Å, Jain K, Garcia-Caraballo S, Castro J, Brierley SM, Alewood PF, Lewis RJ. Conopeptide-Derived κ-Opioid Agonists (Conorphins): Potent, Selective, and Metabolic Stable Dynorphin A Mimetics with Antinociceptive Properties. J Med Chem 2016; 59:2381-95. [PMID: 26859603 DOI: 10.1021/acs.jmedchem.5b00911] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Opioid receptor screening of a conopeptide library led to a novel selective κ-opioid agonist peptide (conorphin T). Intensive medicinal chemistry, guided by potency, selectivity, and stability assays generated a pharmacophore model supporting rational design of highly potent and selective κ-opioid receptor (KOR) agonists (conorphins) with exceptional plasma stability. Conorphins are defined by a hydrophobic benzoprolyl moiety, a double arginine sequence, a spacer amino acid followed by a hydrophobic residue and a C-terminal vicinal disulfide moiety. The pharmacophore model was supported by computational docking studies, revealing receptor-ligand interactions similar to KOR agonist dynorphin A (1-8). A conorphin agonist inhibited colonic nociceptors in a mouse tissue model of chronic visceral hypersensitivity, suggesting the potential of KOR agonists for the treatment of chronic abdominal pain. This new conorphine KOR agonist class and pharmacophore model provide opportunities for future rational drug development and probes for exploring the role of the κ-opioid receptor.
Collapse
Affiliation(s)
- Andreas Brust
- Xenome Limited , Brisbane, Queensland 4068, Australia.,Institute for Molecular Biosciences, The University of Queensland , Brisbane, Queensland, 4072, Australia
| | - Daniel E Croker
- Xenome Limited , Brisbane, Queensland 4068, Australia.,Institute for Molecular Biosciences, The University of Queensland , Brisbane, Queensland, 4072, Australia
| | - Barbara Colless
- Xenome Limited , Brisbane, Queensland 4068, Australia.,Institute for Molecular Biosciences, The University of Queensland , Brisbane, Queensland, 4072, Australia
| | - Lotten Ragnarsson
- Xenome Limited , Brisbane, Queensland 4068, Australia.,Institute for Molecular Biosciences, The University of Queensland , Brisbane, Queensland, 4072, Australia
| | - Åsa Andersson
- Xenome Limited , Brisbane, Queensland 4068, Australia.,Institute for Molecular Biosciences, The University of Queensland , Brisbane, Queensland, 4072, Australia
| | - Kapil Jain
- Institute for Molecular Biosciences, The University of Queensland , Brisbane, Queensland, 4072, Australia
| | - Sonia Garcia-Caraballo
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Disease, Discipline of Medicine, The University of Adelaide, South Australian Health and Medical Research Institute, SAHMRI , Adelaide, SA 5000, Australia
| | - Joel Castro
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Disease, Discipline of Medicine, The University of Adelaide, South Australian Health and Medical Research Institute, SAHMRI , Adelaide, SA 5000, Australia
| | - Stuart M Brierley
- Visceral Pain Group, Centre for Nutrition and Gastrointestinal Disease, Discipline of Medicine, The University of Adelaide, South Australian Health and Medical Research Institute, SAHMRI , Adelaide, SA 5000, Australia
| | - Paul F Alewood
- Institute for Molecular Biosciences, The University of Queensland , Brisbane, Queensland, 4072, Australia
| | - Richard J Lewis
- Xenome Limited , Brisbane, Queensland 4068, Australia.,Institute for Molecular Biosciences, The University of Queensland , Brisbane, Queensland, 4072, Australia
| |
Collapse
|
12
|
Pless SA, Kim RY, Ahern CA, Kurata HT. Atom-by-atom engineering of voltage-gated ion channels: magnified insights into function and pharmacology. J Physiol 2015; 593:2627-34. [PMID: 25640301 DOI: 10.1113/jphysiol.2014.287714] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 01/26/2015] [Indexed: 12/12/2022] Open
Abstract
Unnatural amino acid incorporation into ion channels has proven to be a valuable approach to interrogate detailed hypotheses arising from atomic resolution structures. In this short review, we provide a brief overview of some of the basic principles and methods for incorporation of unnatural amino acids into proteins. We also review insights into the function and pharmacology of voltage-gated ion channels that have emerged from unnatural amino acid mutagenesis approaches.
Collapse
Affiliation(s)
- Stephan A Pless
- Center for Biopharmaceuticals, Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Robin Y Kim
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, BC, Canada
| | | | - Harley T Kurata
- Department of Anesthesiology, Pharmacology, and Therapeutics, University of British Columbia, Vancouver, BC, Canada
| |
Collapse
|
13
|
Zhu Q, Kao L, Azimov R, Abuladze N, Newman D, Kurtz I. Interplay between disulfide bonding and N-glycosylation defines SLC4 Na+-coupled transporter extracellular topography. J Biol Chem 2015; 290:5391-404. [PMID: 25568315 DOI: 10.1074/jbc.m114.619320] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The extracellular loop 3 (EL-3) of SLC4 Na(+)-coupled transporters contains 4 highly conserved cysteines and multiple N-glycosylation consensus sites. In the electrogenic Na(+)-HCO3(-) cotransporter NBCe1-A, EL-3 is the largest extracellular loop and is predicted to consist of 82 amino acids. To determine the structural-functional importance of the conserved cysteines and the N-glycosylation sites in NBCe1-A EL-3, we analyzed the potential interplay between EL-3 disulfide bonding and N-glycosylation and their roles in EL-3 topological folding. Our results demonstrate that the 4 highly conserved cysteines form two intramolecular disulfide bonds, Cys(583)-Cys(585) and Cys(617)-Cys(642), respectively, that constrain EL-3 in a folded conformation. The formation of the second disulfide bond is spontaneous and unaffected by the N-glycosylation state of EL-3 or the first disulfide bond, whereas formation of the first disulfide bond relies on the presence of the second disulfide bond and is affected by N-glycosylation. Importantly, EL-3 from each monomer is adjacently located at the NBCe1-A dimeric interface. When the two disulfide bonds are missing, EL-3 adopts an extended conformation highly accessible to protease digestion. This unique adjacent parallel location of two symmetrically folded EL-3 loops from each monomer resembles a domain-like structure that is potentially important for NBCe1-A function in vivo. Moreover, the formation of this unique structure is critically dependent on the finely tuned interplay between disulfide bonding and N-glycosylation in the membrane processed NBCe1-A dimer.
Collapse
Affiliation(s)
| | - Liyo Kao
- From the Department of Medicine and
| | | | | | | | - Ira Kurtz
- From the Department of Medicine and Brain Research Institute, David Geffen School of Medicine, UCLA, Los Angeles, California 90095-1689
| |
Collapse
|
14
|
Daeffler KNM, Lester HA, Dougherty DA. Functional evaluation of key interactions evident in the structure of the eukaryotic Cys-loop receptor GluCl. ACS Chem Biol 2014; 9:2283-90. [PMID: 25051140 PMCID: PMC4201344 DOI: 10.1021/cb500323d] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
![]()
The
publication of the first high-resolution crystal structure
of a eukaryotic Cys-loop receptor, GluClα, has provided valuable
structural information on this important class of ligand-gated ion
channels (LGIC). However, limited functional data exist for the GluCl
receptors. Before applying the structural insights from GluCl to mammalian
Cys-loop receptors such as nicotinic acetylcholine and GABA receptors,
it is important to ensure that established functional features of mammalian Cys-loop receptors are present in the more
distantly related GluCl receptors. Here, we seek to identify ligand-binding
interactions that are generally associated with Cys-loop receptors,
including the frequently observed cation−π interaction.
Our studies were performed on the highly homologous GluClβ receptor,
because GluClα is not activated by glutamate in Xenopus
laevis oocytes. Mutagenesis of the signal peptide and pore
lining helix was performed to enhance functional expression and sensitivity
to applied ligand, respectively. Conventional and unnatural amino
acid mutagenesis indicate a strong cation−π interaction
between Y206 and the protonated amine of glutamate, as well as other
important ionic and hydrogen bond interactions between the ligand
and the binding site, consistent with the crystal structure.
Collapse
Affiliation(s)
- Kristina N.-M. Daeffler
- Division of Chemistry & Chemical Engineering and ‡Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Henry A. Lester
- Division of Chemistry & Chemical Engineering and ‡Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Dennis A. Dougherty
- Division of Chemistry & Chemical Engineering and ‡Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
| |
Collapse
|
15
|
Dougherty DA, Van Arnam EB. In vivo incorporation of non-canonical amino acids by using the chemical aminoacylation strategy: a broadly applicable mechanistic tool. Chembiochem 2014; 15:1710-20. [PMID: 24990307 DOI: 10.1002/cbic.201402080] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Indexed: 01/05/2023]
Abstract
We describe a strategy for incorporating non-canonical amino acids site-specifically into proteins expressed in living cells, involving organic synthesis to chemically aminoacylate a suppressor tRNA, protein expression in Xenopus oocytes, and monitoring protein function, primarily by electrophysiology. With this protocol, a very wide range of non-canonical amino acids can be employed, allowing both systematic structure-function studies and the incorporation of reactive functionalities. Here, we present an overview of the methodology and examples meant to illustrate the versatility and power of the method as a tool for investigating protein structure and function.
Collapse
Affiliation(s)
- Dennis A Dougherty
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (USA).
| | | |
Collapse
|
16
|
Van Arnam EB, Dougherty DA. Functional probes of drug-receptor interactions implicated by structural studies: Cys-loop receptors provide a fertile testing ground. J Med Chem 2014; 57:6289-300. [PMID: 24568098 PMCID: PMC4136689 DOI: 10.1021/jm500023m] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
![]()
Structures
of integral membrane receptors provide valuable models
for drug–receptor interactions across many important classes
of drug targets and have become much more widely available in recent
years. However, it remains to be determined to what extent these images
are relevant to human receptors in their biological context and how
subtle issues such as subtype selectivity can be informed by them.
The high precision structural modifications enabled by unnatural amino
acid mutagenesis on mammalian receptors expressed in vertebrate cells
allow detailed tests of predictions from structural studies. Using
the Cys-loop superfamily of ligand-gated ion channels, we show that
functional studies lead to detailed binding models that, at times,
are significantly at odds with the structural studies on related invertebrate
proteins. Importantly, broad variations in binding interactions are
seen for very closely related receptor subtypes and for varying drugs
at a given binding site. These studies highlight the essential interplay
between structural studies and functional studies that can guide efforts
to develop new pharmaceuticals.
Collapse
Affiliation(s)
- Ethan B Van Arnam
- Division of Chemistry and Chemical Engineering, California Institute of Technology , Pasadena, California 91125, United States
| | | |
Collapse
|
17
|
Brust A, Wang CIA, Daly NL, Kennerly J, Sadeghi M, Christie MJ, Lewis RJ, Mobli M, Alewood PF. Vicinal Disulfide Constrained Cyclic Peptidomimetics: a Turn Mimetic Scaffold Targeting the Norepinephrine Transporter. Angew Chem Int Ed Engl 2013; 52:12020-3. [DOI: 10.1002/anie.201304660] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2013] [Revised: 08/02/2013] [Indexed: 12/28/2022]
|
18
|
Brust A, Wang CIA, Daly NL, Kennerly J, Sadeghi M, Christie MJ, Lewis RJ, Mobli M, Alewood PF. Vicinal Disulfide Constrained Cyclic Peptidomimetics: a Turn Mimetic Scaffold Targeting the Norepinephrine Transporter. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201304660] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
|
19
|
Abstract
It has been known for many decades that cell surface, soluble-secreted, and extracellular matrix proteins are generally rich in disulfide bonds, but only more recently has the functional diversity of disulfide bonding in extracellular proteins been appreciated. In addition to the classic mechanisms by which disulfide bonds enhance protein thermodynamic stability, disulfides in certain configurations contribute particular mechanical properties to proteins that sense and respond to tensile forces. Disulfides may help warp protein folds for the evolution of new functions, or they may fasten aggregation-prone flaps of polypeptide to protein surfaces to prevent fibrilization or oligomerization. Disulfides can also be used to package and secure macromolecular cargo for intercellular transport. A series of case studies illustrating diverse biophysical roles of disulfide bonding are reviewed, with a focus on proteins functioning in the extracellular environment.
Collapse
Affiliation(s)
- Deborah Fass
- Department of Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel.
| |
Collapse
|
20
|
Pless SA, Ahern CA. Unnatural Amino Acids as Probes of Ligand-Receptor Interactions and Their Conformational Consequences. Annu Rev Pharmacol Toxicol 2013; 53:211-29. [DOI: 10.1146/annurev-pharmtox-011112-140343] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Stephan A. Pless
- Department of Anesthesiology, Pharmacology and Therapeutics and Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z3
| | - Christopher A. Ahern
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, Iowa 52242;
| |
Collapse
|