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Valente P, Kiryushko D, Sacchetti S, Machado P, Cobley CM, Mangini V, Porter AE, Spatz JP, Fleck RA, Benfenati F, Fiammengo R. Reply to Comment on Conopeptide-Functionalized Nanoparticles Selectively Antagonize Extrasynaptic N-Methyl-d-aspartate Receptors and Protect Hippocampal Neurons from Excitotoxicity In Vitro. ACS NANO 2021; 15:15409-15417. [PMID: 37738397 DOI: 10.1021/acsnano.1c05607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/24/2023]
Affiliation(s)
- Pierluigi Valente
- Department of Experimental Medicine, School of Medical and Pharmaceutical Sciences, University of Genoa, Genoa 16132, Italy
- IRCSS Ospedale Policlinico San Martino, Genoa 16132, Italy
| | - Darya Kiryushko
- Department of Materials and London Center for Nanotechnology, Imperial College, London SW72AZ, United Kingdom
- Center for Neuroinflammation and Neurodegeneration, Imperial College London, London W12 0NN, United Kingdom
| | - Silvio Sacchetti
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa 16132, Italy
| | - Pedro Machado
- Centre for Ultrastructural Imaging, Kings College London, London SE1 1UL, United Kingdom
| | - Claire M Cobley
- Department of Physical Chemistry, University of Heidelberg, Heidelberg 69120, Germany
- Max Planck Institute for Intelligent Systems, Stuttgart 70569, Germany
| | - Vincenzo Mangini
- Center for Biomolecular Nanotechnologies@UniLe, Istituto Italiano di Tecnologia, Arnesano, Lecce 73010, Italy
| | - Alexandra E Porter
- Department of Materials and London Center for Nanotechnology, Imperial College, London SW72AZ, United Kingdom
| | - Joachim P Spatz
- Department of Physical Chemistry, University of Heidelberg, Heidelberg 69120, Germany
- Max Planck Institute for Medical Research, Heidelberg 69120, Germany
| | - Roland A Fleck
- Centre for Ultrastructural Imaging, Kings College London, London SE1 1UL, United Kingdom
| | - Fabio Benfenati
- IRCSS Ospedale Policlinico San Martino, Genoa 16132, Italy
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, Genoa 16132, Italy
| | - Roberto Fiammengo
- Center for Biomolecular Nanotechnologies@UniLe, Istituto Italiano di Tecnologia, Arnesano, Lecce 73010, Italy
- Department of Biotechnology, University of Verona, Verona 37134, Italy
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2
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A Conantokin Peptide Con-T[M8Q] Inhibits Morphine Dependence with High Potency and Low Side Effects. Mar Drugs 2021; 19:md19010044. [PMID: 33478061 PMCID: PMC7835912 DOI: 10.3390/md19010044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/07/2021] [Accepted: 01/08/2021] [Indexed: 12/15/2022] Open
Abstract
N-methyl-D-aspartate receptor (NMDAR) antagonists have been found to be effective to inhibit morphine dependence. However, the discovery of the selective antagonist for NMDAR GluN2B with low side-effects still remains challenging. In the present study, we report a selective NMDAR GluN2B antagonist con-T[M8Q](a conantokin-T variant) that potently inhibits the naloxone-induced jumping and conditioned place preference of morphine-dependent mice at nmol/kg level, 100-fold higher than ifenprodil, a classical NMDAR NR2B antagonist. Con-T[M8Q] displays no significant impacts on coordinated locomotion function, spontaneous locomotor activity, and spatial memory mice motor function at the dose used. Further molecular mechanism experiments demonstrate that con-T[M8Q] effectively inhibited the transcription and expression levels of signaling molecules related to NMDAR NR2B subunit in hippocampus, including NR2B, p-NR2B, CaMKII-α, CaMKII-β, CaMKIV, pERK, and c-fos. The high efficacy and low side effects of con-T[M8Q] make it a good lead compound for the treatment of opiate dependence and for the reduction of morphine usage.
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Li L, Liu N, Ding R, Wang S, Liu Z, Li H, Zheng X, Dai Q. A novel 4/6-type alpha-conotoxin ViIA selectively inhibits nAchR α3β2 subtype. Acta Biochim Biophys Sin (Shanghai) 2015; 47:1023-8. [PMID: 26511093 DOI: 10.1093/abbs/gmv105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 08/24/2015] [Indexed: 01/01/2023] Open
Abstract
Conotoxins (CTxs) are typically small peptides composed of 12-50 amino acid residues with 2-5 disulfide bridges. Most of them potently and selectively target a wide variety of ion channels and membrane receptors. They are highly valued as neuropharmacological probes and in pharmaceutical development. In this work, a novel α4/6-CTx named ViIA (RDCCSNPPCAHNNPDC-NH2) was identified from a cDNA library of the venom ducts of Conus virgo (C. virgo). ViIA was then synthesized chemically and its disulfide connectivity was identified as 'C(1)-C(3), C(2)-C(4)'. Its molecular targets were further assessed using two-electrode voltage clamping. The results indicated that ViIA selectively inhibited nicotinic acetylcholine receptor (nAChR) α3β2 subtype with an IC50 of 845.5 nM, but did not target dorsal root ganglion sodium (Na(+))-, potassium (K(+))- or calcium (Ca(2+))-ion channels. Further structure-activity relationship analysis demonstrated that Arg(1) and His(11) but not Asp(2) were the functional residues. To the best of our knowledge, ViIA is the first 4/6 α-CTx that selectively inhibits nAChR α3β2 subtype. This finding expands the knowledge of targets of α4/6-family CTxs.
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Affiliation(s)
- Liang Li
- Institute of Pharmacy and Pharmacology, University of South China, Hengyang 421001, China Beijing Institute of Biotechnology, Beijing 100071, China
| | - Na Liu
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Rong Ding
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Shuo Wang
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Zhuguo Liu
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Haiying Li
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Xing Zheng
- Institute of Pharmacy and Pharmacology, University of South China, Hengyang 421001, China
| | - Qiuyun Dai
- Beijing Institute of Biotechnology, Beijing 100071, China
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Wang F, Yan Z, Liu Z, Wang S, Wu Q, Yu S, Ding J, Dai Q. Molecular basis of toxicity of N-type calcium channel inhibitor MVIIA. Neuropharmacology 2015; 101:137-45. [PMID: 26344359 DOI: 10.1016/j.neuropharm.2015.08.047] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 08/31/2015] [Accepted: 08/31/2015] [Indexed: 10/23/2022]
Abstract
MVIIA (ziconotide) is a specific inhibitor of N-type calcium channel, Cav2.2. It is derived from Cone snail and currently used for the treatment of severe chronic pains in patients unresponsive to opioid therapy. However, MVIIA produces severe side-effects, including dizziness, nystagmus, somnolence, abnormal gait, and ataxia, that limit its wider application. We previously identified a novel inhibitor of Cav2.2, ω-conopeptide SO-3, which possesses similar structure and analgesic activity to MVIIA's. To investigate the key residues for MVIIA toxicity, MVIIA/SO-3 hybrids and MVIIA variants carrying mutations in its loop 2 were synthesized. The substitution of MVIIA's loop 1 with the loop 1 of SO-3 resulted in significantly reduced Cav2.2 binding activity in vitro; the replacement of MVIIA loop 2 by the loop 2 of SO-3 not only enhanced the peptide/Cav2.2 binding but also decreased its toxicity on goldfish, attenuated mouse tremor symptom, spontaneous locomotor activity, and coordinated locomotion function. Further mutation analysis and molecular calculation revealed that the toxicity of MVIIA mainly arose from Met(12) in the loop 2, and this residue inserts into a hydrophobic hole (Ile(300), Phe(302) and Leu(305)) located between repeats II and III of Cav2.2. The combinative mutations of the loop 2 of MVIIA or other ω-conopeptides may be used for future development of more effective Cav2.2 inhibitors with lower side effects.
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Affiliation(s)
- Fei Wang
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Zhenzhen Yan
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Zhuguo Liu
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Sheng Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Qiaoling Wu
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Shuo Yu
- Beijing Institute of Biotechnology, Beijing 100071, China
| | - Jiuping Ding
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, China.
| | - Qiuyun Dai
- Beijing Institute of Biotechnology, Beijing 100071, China.
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5
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Con-T[M8Q] potently attenuates the expression and development of morphine tolerance in mice. Neurosci Lett 2015; 597:38-42. [DOI: 10.1016/j.neulet.2015.04.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 03/19/2015] [Accepted: 04/14/2015] [Indexed: 01/14/2023]
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6
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Wang S, Zhao C, Liu Z, Wang X, Liu N, Du W, Dai Q. Structural and Functional Characterization of a Novel α-Conotoxin Mr1.7 from Conus marmoreus Targeting Neuronal nAChR α3β2, α9α10 and α6/α3β2β3 Subtypes. Mar Drugs 2015; 13:3259-75. [PMID: 26023835 PMCID: PMC4483627 DOI: 10.3390/md13063259] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 05/11/2015] [Indexed: 12/26/2022] Open
Abstract
In the present study, we synthesized and, structurally and functionally characterized a novel α4/7-conotoxin Mr1.7 (PECCTHPACHVSHPELC-NH2), which was previously identified by cDNA libraries from Conus marmoreus in our lab. The NMR solution structure showed that Mr1.7 contained a 310-helix from residues Pro7 to His10 and a type I β-turn from residues Pro14 to Cys17. Electrophysiological results showed that Mr1.7 selectively inhibited the α3β2, α9α10 and α6/α3β2β3 neuronal nicotinic acetylcholine receptors (nAChRs) with an IC50 of 53.1 nM, 185.7 nM and 284.2 nM, respectively, but showed no inhibitory activity on other nAChR subtypes. Further structure-activity studies of Mr1.7 demonstrated that the PE residues at the N-terminal sequence of Mr1.7 were important for modulating its selectivity, and the replacement of Glu2 by Ala resulted in a significant increase in potency and selectivity to the α3β2 nAChR. Furthermore, the substitution of Ser12 with Asn in the loop2 significantly increased the binding of Mr1.7 to α3β2, α3β4, α2β4 and α7 nAChR subtypes. Taken together, this work expanded our knowledge of selectivity and provided a new way to improve the potency and selectivity of inhibitors for nAChR subtypes.
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Affiliation(s)
- Shuo Wang
- Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Cong Zhao
- Department of Chemistry, Renmin University of China, Beijing 100872, China.
| | - Zhuguo Liu
- Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Xuesong Wang
- Department of Chemistry, Renmin University of China, Beijing 100872, China.
| | - Na Liu
- Beijing Institute of Biotechnology, Beijing 100071, China.
| | - Weihong Du
- Department of Chemistry, Renmin University of China, Beijing 100872, China.
| | - Qiuyun Dai
- Beijing Institute of Biotechnology, Beijing 100071, China.
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7
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Characterization of a T-superfamily conotoxin TxVC from Conus textile that selectively targets neuronal nAChR subtypes. Biochem Biophys Res Commun 2014; 454:151-6. [DOI: 10.1016/j.bbrc.2014.10.055] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 10/12/2014] [Indexed: 11/19/2022]
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8
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Huang L, Balsara RD, Castellino FJ. Synthetic conantokin peptides potently inhibit N-methyl-D-aspartate receptor-mediated currents of retinal ganglion cells. J Neurosci Res 2014; 92:1767-74. [PMID: 25043917 DOI: 10.1002/jnr.23447] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 05/12/2014] [Accepted: 06/01/2014] [Indexed: 01/16/2023]
Abstract
Retinal ganglion cells (RGCs), which are the sole output neurons of the retina, express N-methyl-D-aspartate receptors (NMDARs), rendering these cells susceptible to glutamate excitotoxicity, with implications for loss of normal RGC excitatory responses in disorders such as glaucoma and diabetic retinopathy. Therefore, antagonists that inhibit NMDAR-mediated currents specifically by targeting the GluN2B component of the ion channel have the potential to serve as a basis for developing potential therapeutics. The roles of peptidic conantokins, which are potent brain neuronal NMDAR inhibitors, were studied. By using patch-clamp whole-cell analyses in dissociated RGCs and retinal whole-mount RGCs, we evaluated the effects of synthetic conantokin-G (conG) and conantokin-T (conT), which are small γ-carboxyglutamate-containing peptides, on NMDA-mediated excitatory responses in mouse RGCs. Both conG and conT inhibited the NMDA-mediated currents of dark-adapted dissociated and whole-mount RGCs in a dose-dependent, reversible, noncompetitive manner. Inhibition of NMDA-mediated steady-state currents by NMDAR nonsubunit-selective conT was approximately threefold greater than GluN2B-selective conG or ifenprodil, demonstrating its potential ability to inhibit both GluN2A- and GluN2B-containing ion channels in RGCs. Because the extent of inhibition of NMDA-evoked currents by conG and the pharmacologic GluN2B-selective inhibitor ifenprodil were similar (40-45%) to that of the GluN2A-selective antagonist NVP-AAM0077, we conclude that the levels of GluN2A and GluN2B subunits are similar in RGCs. These results provide a novel basis for developing effective neuroprotective agents to aid in the prevention of undesired glutamatergic excitotoxicity in neurodegenerative diseases of the retina and demonstrate functional assembly of NMDARs in RGCs.
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Affiliation(s)
- Luoxiu Huang
- W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, Indiana
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Kunda S, Cheriyan J, Hur M, Balsara RD, Castellino FJ. Antagonist properties of Conus parius peptides on N-methyl-D-aspartate receptors and their effects on CREB signaling. PLoS One 2013; 8:e81405. [PMID: 24260577 PMCID: PMC3832412 DOI: 10.1371/journal.pone.0081405] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 10/22/2013] [Indexed: 02/05/2023] Open
Abstract
Three members of a family of small neurotoxic peptides from the venom of Conus parius, conantokins (Con) Pr1, Pr2, and Pr3, function as antagonists of N-methyl-D-aspartate receptors (NMDAR). We report structural characterizations of these synthetic peptides, and also demonstrate their antagonistic properties toward ion flow through NMDAR ion channels in primary neurons. ConPr1 and ConPr2 displayed moderate increases in α-helicity after addition of Mg2+. Native apo-ConPr3 possessed an α-helical conformation, and the helicity increased only slightly on addition of Mg2+. Additionally, these peptides diminished NMDA/Gly-mediated currents and intracellular Ca2+ (iCa2+) influx in mature rat primary hippocampal neurons. Electrophysiological data showed that these peptides displayed slower antagonistic properties toward the NMDAR than conantokins from other species of cone snails, e.g., ConT and ConG. Furthermore, to demonstrate selectivity of the C. parius-derived conantokins towards specific NMDAR subunits, cortical neurons from GluN2A-/- and GluN2B-/- mice were utilized. Robust inhibition of NMDAR-mediated stimulation in GluN2A-/--derived mouse neurons, as compared to those isolated from GluN2B-/--mouse brains, was observed, suggesting a greater selectivity of these antagonists towards the GluN2B subunit. These C. parius conantokins mildly inhibited NMDAR-induced phosphorylation of CREB at Ser133, suggesting that the peptides modulated iCa2+ entry and, thereby, activation of CREB, a transcription factor that is required for maintaining long-term synaptic activity. Our data mechanistically show that while these peptides effectively antagonize NMDAR-directed current and iCa2+ influx, receptor-coupled CREB signaling is maintained. The consequence of sustained CREB signaling is improved neuronal plasticity and survival during neuropathologies.
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Affiliation(s)
- Shailaja Kunda
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - John Cheriyan
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Michael Hur
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Rashna D. Balsara
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
| | - Francis J. Castellino
- W.M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, United States of America
- * E-mail:
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α -RgIB: A Novel Antagonist Peptide of Neuronal Acetylcholine Receptor Isolated from Conus regius Venom. INTERNATIONAL JOURNAL OF PEPTIDES 2013; 2013:543028. [PMID: 23533449 PMCID: PMC3600190 DOI: 10.1155/2013/543028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 01/16/2013] [Accepted: 01/16/2013] [Indexed: 11/18/2022]
Abstract
Conus venoms are rich sources of biologically active peptides that act specifically on ionic channels and metabotropic receptors present at the neuromuscular junction, efficiently paralyzing the prey. Each species of Conus may have 50 to 200 uncharacterized bioactive peptides with pharmacological interest. Conus regius is a vermivorous species that inhabits Northeastern Brazilian tropical waters. In this work, we characterized one peptide with activity on neuronal acetylcholine receptor (nAChR). Crude venom was purified by reverse-phase HPLC and selected fractions were screened and sequenced by mass spectrometry, MALDI-ToF, and ESI-Q-ToF, respectively. A new peptide was identified, bearing two disulfide bridges. The novel 2,701 Da peptide belongs to the cysteine framework I, corresponding to the cysteine pattern CC-C-C. The biological activity of the purified peptide was tested by intracranial injection in mice, and it was observed that high concentrations induced hyperactivity in the animals, whereas lower doses caused breathing difficulty. The activity of this peptide was assayed in patch-clamp experiments, on nAChR-rich cells, in whole-cell configuration. The peptide blocked slow rise-time neuronal receptors, probably α3β4 and/or α3β4α5 subtype. According to the nomenclature, the new peptide was designated as α-RgIB.
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Zhang N, Li BQ, Gao S, Ruan JS, Cai YD. Computational prediction and analysis of protein γ-carboxylation sites based on a random forest method. MOLECULAR BIOSYSTEMS 2012; 8:2946-55. [PMID: 22918520 DOI: 10.1039/c2mb25185j] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The glutamate γ-carboxylation plays a pivotal part in a number of important human diseases. However, traditional protein γ-carboxylation site detection by experimental approaches are often laborious and time-consuming. In this study, we initiated an attempt for the computational prediction of protein γ-carboxylation sites. We developed a new method for predicting the γ-carboxylation sites based on a Random Forest method. As a result, 90.44% accuracy and 0.7739 MCC value were obtained for the training dataset, and 89.83% accuracy and 0.7448 MCC value for the testing dataset. Our method considered several features including sequence conservation, residual disorder, secondary structures, solvent accessibility, physicochemical/biochemical properties and amino acid occurrence frequencies. By means of the feature selection algorithm, an optimal set of 327 features were selected; these features were considered as the ones that contributed significantly to the prediction of protein γ-carboxylation sites. Analysis of the optimal feature set indicated several important factors in determining the γ-carboxylation and a possible consensus sequence of the γ-carboxylation recognition site (γ-CRS) was suggested. These may shed some light on the in-depth understanding of the mechanisms of γ-carboxylation, providing guidelines for experimental validation.
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Affiliation(s)
- Ning Zhang
- Department of Biomedical Engineering Tianjin University, Tianjin Key Lab of BME Measurement, Tianjin, 300072, PR China
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Bohlen CJ, Julius D. Receptor-targeting mechanisms of pain-causing toxins: How ow? Toxicon 2012; 60:254-64. [PMID: 22538196 DOI: 10.1016/j.toxicon.2012.04.336] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 04/04/2012] [Indexed: 12/15/2022]
Abstract
Venoms often target vital processes to cause paralysis or death, but many types of venom also elicit notoriously intense pain. While these pain-producing effects can result as a byproduct of generalized tissue trauma, there are now multiple examples of venom-derived toxins that target somatosensory nerve terminals in order to activate nociceptive (pain-sensing) neural pathways. Intriguingly, investigation of the venom components that are responsible for evoking pain has revealed novel roles and/or configurations of well-studied toxin motifs. This review serves to highlight pain-producing toxins that target the capsaicin receptor, TRPV1, or members of the acid-sensing ion channel family, and to discuss the utility of venom-derived multivalent and multimeric complexes.
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Affiliation(s)
- Christopher J Bohlen
- Department of Physiology, University of California, San Francisco, CA 94158-2517, USA.
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Sheng Z, Prorok M, Castellino FJ. Specific determinants of conantokins that dictate their selectivity for the NR2B subunit of N-methyl-D-aspartate receptors. Neuroscience 2010; 170:703-10. [PMID: 20688135 DOI: 10.1016/j.neuroscience.2010.07.056] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Revised: 07/26/2010] [Accepted: 07/28/2010] [Indexed: 10/19/2022]
Abstract
Conantokins are naturally-occurring small peptide antagonists of ion flow through NMDA/glycine activated-N-methyl-d-aspartate receptor (NMDAR) ion channels. One member of the conantokin family, conantokin (con)-G, a 17-residue peptide, is selective for NMDARs containing the N-methyl-d-aspartate receptor subunit 2 B (NR2B), whereas the homologous peptides, con-T and con-R, show broader selectivity for NR2 subunits. In this study, con-G, con-R, and con-T variants were chemically synthesized and employed to investigate their subunit selectivities as inhibitors of agonist-evoked ion currents in human embryonic kidney-293 (HEK-293) cells expressing various combinations of NMDAR subunits that contain NR1a or NR1b combined with NR2A or NR2B. Using truncation and point mutants, as well as chimeric conantokins, we determined that the N-terminus of con-G contains all the determinants for NR2B selectivity. With this information, a large number of (con) variants were synthesized and used to establish minimal sequence determinants for selectivity. Tyr at position 5 broadens the NR2 selectivity, and recovery of NR2B selectivity in Tyr5 peptides was achieved by incorporating Ala or Gly at position 8. NR2B selectivity in con-R can be conferred through deletion of the Ala at position 10, thereby shifting the γ-carboxyglutamate (Gla) from position 11 to position 10, where a Gla naturally occurs in con-G and con-T. The nature of the amino acid at position 6 is also linked to subunit selectivity. Our studies suggest that the molecular determinants of conantokins that dictate NMDAR subunit selectivity are housed in specific residues of the N-termini of these peptides. Thus, it is possible to engineer desired NMDAR functional properties into conantokin-based peptides.
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Affiliation(s)
- Z Sheng
- W. M. Keck Center for Transgene Research and Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556, USA
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14
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Cnudde SE, Prorok M, Castellino FJ, Geiger JH. Metal ion determinants of conantokin dimerization as revealed in the X-ray crystallographic structure of the Cd(2+)/Mg (2+)-con-T[K7gamma] complex. J Biol Inorg Chem 2010; 15:667-75. [PMID: 20195692 PMCID: PMC3693470 DOI: 10.1007/s00775-010-0633-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Accepted: 02/11/2010] [Indexed: 10/19/2022]
Abstract
Predatory sea snails from the Conus family produce a variety of venomous small helical peptides called conantokins that are rich in gamma-carboxyglutamic acid (Gla) residues. As potent and selective antagonists of the N-methyl-D: -aspartate receptor, these peptides are potential therapeutic agents for a variety of neurological conditions. The two most studied members of this family of peptides are con-G and con-T. Con-G has Gla residues at sequence positions 3, 4, 7, 10, and 14, and requires divalent cation binding to adopt a helical conformation. Although both Ca(2+) and Mg(2+) can fulfill this role, Ca(2+) induces dimerization of con-G, whereas the Mg(2+)-complexed peptide remains monomeric. A variant of con-T, con-T[K7gamma] (gamma is Gla), contains Gla residues at the same five positions as in con-G and behaves very similarly with respect to metal ion binding and dimerization; each peptide binds two Ca(2+) ions and two Mg(2+) ions per helix. To understand the difference in metal ion selectivity, affinity, and the dependence on Ca(2+) for dimer formation, we report here the structure of the monomeric Cd(2+)/Mg(2+)-con-T[K7gamma] complex, and, by comparison with the previously published con-T[K7gamma]/Ca(2+) dimer structure, we suggest explanations for both metal ion binding site specificity and metal-ion-dependent dimerization.
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Affiliation(s)
- Sara E. Cnudde
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Mary Prorok
- Department of Chemistry and Biochemistry, W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Francis J. Castellino
- Department of Chemistry and Biochemistry, W.M. Keck Center for Transgene Research, University of Notre Dame, Notre Dame, IN 46556, USA
| | - James H. Geiger
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
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Liu Z, Xu N, Hu J, Zhao C, Yu Z, Dai Q. Identification of novel I-superfamily conopeptides from several clades of Conus species found in the South China Sea. Peptides 2009; 30:1782-7. [PMID: 19595726 DOI: 10.1016/j.peptides.2009.06.036] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 06/26/2009] [Accepted: 06/26/2009] [Indexed: 11/20/2022]
Abstract
The I-superfamily of Conus peptides represents a new class of peptides with four disulfide bridges (-C-C-CC-CC-C-C-) that falls into three (I1, I2 and I3) categories according to the different signal peptide sequences. The I-superfamily has received increasing attention because it targets K+ ion channels, a function that is relatively rare in conotoxins. Herein we report 11 novel I-superfamily conotoxins from the venom ducts of five Cone snails (Conus eburneus, Conus imperialis, Conus vitulinus, Conus emaciatus and Conus litteratus) native to the South China Sea using a primer designed according to the N-terminus of the signal sequence of I2-superfamily conotoxins. The alignment of sequences revealed that signal regions exhibited moderate conservation with the exception of Eb11.3 from C. eburneus with homologies of 21.1%, 38.5% and 30.0% to the signal peptides of I1, I2 and I3 superfamily conotoxins, respectively. The mature peptides ranged from almost identical to highly divergent between species. Analyses of the evolutionary trees of these peptides with those of reported I-superfamily conotoxins showed that nine of them fall in I2 superfamily clades, but two of them were neither I1- and I2- nor I3-superfamily clades. Notably, some peptides exhibited significantly different amino acid residues in the intercysteine loops compared with group A, B and C of I-superfamily conopeptides, suggesting that they may have different bioactivities and functions.
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Affiliation(s)
- Zhuguo Liu
- Beijing Institute of Biotechnology, Beijing 100071, People's Republic of China
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16
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Dai Q, Xiao C, Dong M, Liu Z, Sheng Z, Castellino FJ, Prorok M. Non-strict strand orientation of the Ca2+-induced dimerization of a conantokin peptide variant with sequence-shifted gamma-carboxyglutamate residues. Peptides 2009; 30:866-72. [PMID: 19428763 PMCID: PMC2714806 DOI: 10.1016/j.peptides.2009.01.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 01/12/2009] [Accepted: 01/14/2009] [Indexed: 11/20/2022]
Abstract
We have previously found a new mode of metal ion-induced helix-helix assembly for the gamma-carboxyglutamate (Gla)-containing, neuroactive conantokin (con) peptides that is independent of the hydrophobic effect. In these unique "metallo-zipper" assemblies of con-G and con-T[K7gamma], interhelical Ca(2+) coordination induces dimer formation with strictly antiparallel chain orientation in conantokin peptides in which Gla residues are positioned at "i, i+4, i+7, i+11" intervals. In order to probe the property of self-assembly in conantokin peptides with an extended Gla network, a con-T variant (con-T-tri) was synthesized that contains five Gla residues spaced at "i, i+4, i+7, i+11, i+14" intervals. Sedimentation equilibrium analyses showed that Ca(2+), but not Mg(2+), was capable of promoting con-T-tri self-assembly. Oxidation and rearrangement assays with Cys-containing con-T-tri variants revealed that the peptide strands in the complex can orient in both parallel and antiparallel forms. Stable parallel and antiparallel dimeric forms of con-T-tri were modeled using disulfide-linked peptides and the biological viability of these species was confirmed by electrophysiology. These findings suggest that small changes within the helix-helix interface of the conantokins can be exploited to achieve desired modes of strand alignment.
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Affiliation(s)
- Qiuyun Dai
- From Beijing Institute of Biotechnology, Beijing 100071, China
- To whom correspondence should be addressed: Beijing Institute of Biotechnology, Beijing 100071, China. Tel: 86-10-66948897. Fax: 86-10-63833521.
| | - Cai Xiao
- From Beijing Institute of Biotechnology, Beijing 100071, China
| | - Mingxin Dong
- From Beijing Institute of Biotechnology, Beijing 100071, China
| | | | - Zhenyu Sheng
- Department of Chemistry and Biochemistry, University of Notre Dame, Indiana 46556, USA
| | - Francis J. Castellino
- Department of Chemistry and Biochemistry, University of Notre Dame, Indiana 46556, USA
| | - Mary Prorok
- Department of Chemistry and Biochemistry, University of Notre Dame, Indiana 46556, USA
- To whom correspondence should be addressed: Department of Chemistry and Biochemistry, University of Notre Dame, Indiana 46556, USA. Tel.: 574-6319120. Fax: 574-6314048.
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Bjelić S, Jelesarov I. A survey of the year 2007 literature on applications of isothermal titration calorimetry. J Mol Recognit 2008; 21:289-312. [PMID: 18729242 DOI: 10.1002/jmr.909] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Elucidation of the energetic principles of binding affinity and specificity is a central task in many branches of current sciences: biology, medicine, pharmacology, chemistry, material sciences, etc. In biomedical research, integral approaches combining structural information with in-solution biophysical data have proved to be a powerful way toward understanding the physical basis of vital cellular phenomena. Isothermal titration calorimetry (ITC) is a valuable experimental tool facilitating quantification of the thermodynamic parameters that characterize recognition processes involving biomacromolecules. The method provides access to all relevant thermodynamic information by performing a few experiments. In particular, ITC experiments allow to by-pass tedious and (rarely precise) procedures aimed at determining the changes in enthalpy and entropy upon binding by van't Hoff analysis. Notwithstanding limitations, ITC has now the reputation of being the "gold standard" and ITC data are widely used to validate theoretical predictions of thermodynamic parameters, as well as to benchmark the results of novel binding assays. In this paper, we discuss several publications from 2007 reporting ITC results. The focus is on applications in biologically oriented fields. We do not intend a comprehensive coverage of all newly accumulated information. Rather, we emphasize work which has captured our attention with originality and far-reaching analysis, or else has provided ideas for expanding the potential of the method.
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Affiliation(s)
- Sasa Bjelić
- Biochemisches Institut der Universität Zürich, Winterthurerstrasse 190, Zürich, Switzerland
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18
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Rich RL, Myszka DG. Survey of the year 2007 commercial optical biosensor literature. J Mol Recognit 2008; 21:355-400. [DOI: 10.1002/jmr.928] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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