1
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Roversi D, Troiano C, Salnikov E, Giordano L, Riccitelli F, De Zotti M, Casciaro B, Loffredo MR, Park Y, Formaggio F, Mangoni ML, Bechinger B, Stella L. Effects of antimicrobial peptides on membrane dynamics: A comparison of fluorescence and NMR experiments. Biophys Chem 2023; 300:107060. [PMID: 37336097 DOI: 10.1016/j.bpc.2023.107060] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 05/25/2023] [Accepted: 06/02/2023] [Indexed: 06/21/2023]
Abstract
Antimicrobial peptides (AMPs) represent a promising class of compounds to fight resistant infections. They are commonly thought to kill bacteria by perturbing the permeability of their cell membranes. However, bacterial killing requires a high coverage of the cell surface by bound peptides, at least in the case of cationic and amphipathic AMPs. Therefore, it is conceivable that peptide accumulation on the bacterial membranes might interfere with vital cellular functions also by perturbing bilayer dynamics, a hypothesis that has been termed "sand in the gearbox". Here we performed a systematic study of such possible effects, for two representative peptides (the cationic cathelicidin PMAP-23 and the peptaibol alamethicin), employing fluorescence and NMR spectroscopies. These approaches are commonly applied to characterize lipid order and dynamics, but sample different time-scales and could thus report on different membrane properties. In our case, fluorescence anisotropy measurements on liposomes labelled with probes localized at different depths in the bilayer showed that both peptides perturb membrane fluidity and order. Pyrene excimer-formation experiments showed a peptide-induced reduction in lipid lateral mobility. Finally, laurdan fluorescence indicated that peptide binding reduces water penetration below the headgroups region. Comparable effects were observed also in fluorescence experiments performed directly on live bacterial cells. By contrast, the fatty acyl chain order parameters detected by deuterium NMR spectroscopy remained virtually unaffected by addition of the peptides. The apparent discrepancy between the two techniques confirms previous sporadic observations and is discussed in terms of the different characteristic times of the two approaches. The perturbation of membrane dynamics in the ns timescale, indicated by the multiple fluorescence approaches reported here, could contribute to the antimicrobial activity of AMPs, by affecting the function of membrane proteins, which is strongly dependent on the physicochemical properties of the bilayer.
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Affiliation(s)
- Daniela Roversi
- Department of Chemical Science and Technology, University of Rome Tor Vergata, Rome 00133, Italy
| | - Cassandra Troiano
- Department of Chemical Science and Technology, University of Rome Tor Vergata, Rome 00133, Italy
| | - Evgeniy Salnikov
- RMN et Biophysique des membranes, Institut de Chimie de Strasbourg, CNRS/UMR 7177, Université de Strasbourg, 4, rue Blaise Pascal, Strasbourg 67000, France
| | - Lorenzo Giordano
- Department of Chemical Science and Technology, University of Rome Tor Vergata, Rome 00133, Italy
| | - Francesco Riccitelli
- Department of Chemical Science and Technology, University of Rome Tor Vergata, Rome 00133, Italy
| | - Marta De Zotti
- Department of Chemical Sciences, University of Padova, Padova 35131, Italy
| | - Bruno Casciaro
- Department of Biochemical Sciences, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome 00185, Italy
| | - Maria Rosa Loffredo
- Department of Biochemical Sciences, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome 00185, Italy
| | - Yoonkyung Park
- Department of Biomedical Science and Research Center for Proteinaceous Materials (RCPM), Chosun University, Gwangju, Republic of Korea
| | - Fernando Formaggio
- Department of Chemical Sciences, University of Padova, Padova 35131, Italy
| | - Maria Luisa Mangoni
- Department of Biochemical Sciences, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome 00185, Italy
| | - Burkhard Bechinger
- RMN et Biophysique des membranes, Institut de Chimie de Strasbourg, CNRS/UMR 7177, Université de Strasbourg, 4, rue Blaise Pascal, Strasbourg 67000, France; Institut Universitaire de France, Paris 75005, France
| | - Lorenzo Stella
- Department of Chemical Science and Technology, University of Rome Tor Vergata, Rome 00133, Italy.
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2
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Singh V, Pathania AS, Sharma S, Malik FA, Kumar A, Singh D, Vishwakarma RA. Total Synthesis and Conformational Analysis of Naturally Occurring Lipovelutibols along with Lead Optimization of Lipovelutibol D. ACS OMEGA 2021; 6:6070-6080. [PMID: 33718698 PMCID: PMC7948224 DOI: 10.1021/acsomega.0c04038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 12/31/2020] [Indexed: 06/12/2023]
Abstract
Four lipopeptaibols, namely, lipovelutibols A-D, were recently isolated from psychrotrophic fungus Trichoderma velutinum and reported to have significant cytotoxic activity against HL-60, MDA-MD-231, A549, and LS180 cancer cell lines. In the present study, these peptides were synthesized in a solution using a segment condensation approach. The conformational analysis of these peptides carried out using CD spectrophotometry revealed the formation of 310-helix, and the NMR-VT experiments showed intramolecular hydrogen bonding for NH-5, NH-6, and NH-7. Lipovelutibol D showed potent cytotoxic activity and was chosen for lead optimization. It involved N- and C-terminal truncation, N- and C-terminal modification, random deletion, l/d configuration replacement, and other synthetic analogues. These were tested against various breast cancer cell lines. The C-terminal aldehyde analogue resulting from lead optimization of lipovelutibol D was found to have almost twofold enhanced cytotoxicity against MDA-MB-231 breast cancer cell lines.
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Affiliation(s)
- Varun
Pratap Singh
- Medicinal
Chemistry Division, CSIR−Indian Institute
of Integrative Medicine, Canal Road, Jammu 180001, India
- School
of Biotechnology, Faculty of Sciences, Shri
Mata Vaishno Devi University, Katra, Jammu and Kashmir 182320, India
| | - Anup Singh Pathania
- Academy
of Scientific and Innovative Research, Jammu 180001, India
- Pharmacology
Division, CSIR−Indian Institute of
Integrative Medicine, Canal Road, Jammu, Kashmir 180001, India
| | - Sonia Sharma
- Academy
of Scientific and Innovative Research, Jammu 180001, India
- Pharmacology
Division, CSIR−Indian Institute of
Integrative Medicine, Canal Road, Jammu, Kashmir 180001, India
| | - Fayaz Ahmed Malik
- Academy
of Scientific and Innovative Research, Jammu 180001, India
- Pharmacology
Division, CSIR−Indian Institute of
Integrative Medicine, Canal Road, Jammu, Kashmir 180001, India
| | - Anil Kumar
- School
of Biotechnology, Faculty of Sciences, Shri
Mata Vaishno Devi University, Katra, Jammu and Kashmir 182320, India
| | - Deepika Singh
- Medicinal
Chemistry Division, CSIR−Indian Institute
of Integrative Medicine, Canal Road, Jammu 180001, India
- Academy
of Scientific and Innovative Research, Jammu 180001, India
- Quality
Control and Quality Assurance, CSIR−Indian
Institute of Integrative Medicine, Canal Road, Jammu 180001, India
| | - Ram A. Vishwakarma
- Medicinal
Chemistry Division, CSIR−Indian Institute
of Integrative Medicine, Canal Road, Jammu 180001, India
- Academy
of Scientific and Innovative Research, Jammu 180001, India
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3
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Das S, Ben Haj Salah K, Djibo M, Inguimbert N. Peptaibols as a model for the insertions of chemical modifications. Arch Biochem Biophys 2018; 658:16-30. [DOI: 10.1016/j.abb.2018.09.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 09/05/2018] [Accepted: 09/18/2018] [Indexed: 12/13/2022]
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4
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Syryamina VN, De Zotti M, Toniolo C, Formaggio F, Dzuba SA. Alamethicin self-assembling in lipid membranes: concentration dependence from pulsed EPR of spin labels. Phys Chem Chem Phys 2018; 20:3592-3601. [DOI: 10.1039/c7cp07298h] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The antimicrobial action of the peptide antibiotic alamethicin (Alm) is commonly related to peptide self-assembling resulting in the formation of voltage-dependent channels in bacterial membranes, which induces ion permeation.
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Affiliation(s)
- Victoria N. Syryamina
- Institute of Chemical Kinetics and Combustion
- RAS
- Novosibirsk 630090
- Russian Federation
- Novosibirsk State University
| | - Marta De Zotti
- Department of Chemical Sciences
- University of Padova
- 35131 Padova
- Italy
| | - Claudio Toniolo
- Department of Chemical Sciences
- University of Padova
- 35131 Padova
- Italy
- Institute of Biomolecular Chemistry
| | - Fernando Formaggio
- Department of Chemical Sciences
- University of Padova
- 35131 Padova
- Italy
- Institute of Biomolecular Chemistry
| | - Sergei A. Dzuba
- Institute of Chemical Kinetics and Combustion
- RAS
- Novosibirsk 630090
- Russian Federation
- Novosibirsk State University
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5
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Salnikov ES, Raya J, De Zotti M, Zaitseva E, Peggion C, Ballano G, Toniolo C, Raap J, Bechinger B. Alamethicin Supramolecular Organization in Lipid Membranes from 19F Solid-State NMR. Biophys J 2017; 111:2450-2459. [PMID: 27926846 DOI: 10.1016/j.bpj.2016.09.048] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 09/10/2016] [Accepted: 09/29/2016] [Indexed: 11/24/2022] Open
Abstract
Alamethicins (ALMs) are antimicrobial peptides of fungal origin. Their sequences are rich in hydrophobic amino acids and strongly interact with lipid membranes, where they cause a well-defined increase in conductivity. Therefore, the peptides are thought to form transmembrane helical bundles in which the more hydrophilic residues line a water-filled pore. Whereas the peptide has been well characterized in terms of secondary structure, membrane topology, and interactions, much fewer data are available regarding the quaternary arrangement of the helices within lipid bilayers. A new, to our knowledge, fluorine-labeled ALM derivative was prepared and characterized when reconstituted into phospholipid bilayers. As a part of these studies, C19F3-labeled compounds were characterized and calibrated for the first time, to our knowledge, for 19F solid-state NMR distance and oligomerization measurements by centerband-only detection of exchange (CODEX) experiments, which opens up a large range of potential labeling schemes. The 19F-19F CODEX solid-state NMR experiments performed with ALM in POPC lipid bilayers and at peptide/lipid ratios of 1:13 are in excellent agreement with molecular-dynamics calculations of dynamic pentameric assemblies. When the peptide/lipid ratio was lowered to 1:30, ALM was found in the dimeric form, indicating that the supramolecular organization is tuned by equilibria that can be shifted by changes in environmental conditions.
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Affiliation(s)
- Evgeniy S Salnikov
- Institute of Chemistry, University of Strasbourg/CNRS, UMR7177, Strasbourg, France
| | - Jesus Raya
- Institute of Chemistry, University of Strasbourg/CNRS, UMR7177, Strasbourg, France
| | - Marta De Zotti
- ICB, Padova Unit, CNR, Department of Chemistry, University of Padova, Padova, Italy
| | - Ekaterina Zaitseva
- Department of Membrane Physiology and Technology, Institute of Physiology, University of Freiburg, Freiburg, Germany
| | - Cristina Peggion
- ICB, Padova Unit, CNR, Department of Chemistry, University of Padova, Padova, Italy
| | - Gema Ballano
- ICB, Padova Unit, CNR, Department of Chemistry, University of Padova, Padova, Italy
| | - Claudio Toniolo
- ICB, Padova Unit, CNR, Department of Chemistry, University of Padova, Padova, Italy
| | - Jan Raap
- Leiden Institute of Chemistry, Gorlaeus Laboratories, University of Leiden, Leiden, the Netherlands
| | - Burkhard Bechinger
- Institute of Chemistry, University of Strasbourg/CNRS, UMR7177, Strasbourg, France.
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6
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Milov AD, Tsvetkov YD, Raap J, De Zotti M, Formaggio F, Toniolo C. Review conformation, self-aggregation, and membrane interaction of peptaibols as studied by pulsed electron double resonance spectroscopy. Biopolymers 2016; 106:6-24. [DOI: 10.1002/bip.22713] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 07/29/2015] [Accepted: 08/09/2015] [Indexed: 12/15/2022]
Affiliation(s)
- Alexander D. Milov
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion; Novosibirsk 630090 Russian Federation
| | - Yuri D. Tsvetkov
- V.V. Voevodsky Institute of Chemical Kinetics and Combustion; Novosibirsk 630090 Russian Federation
| | - Jan Raap
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University; 2300 RA Leiden The Netherlands
| | - Marta De Zotti
- Department of Chemistry; University of Padova; Padova 35131 Italy
| | | | - Claudio Toniolo
- Department of Chemistry; University of Padova; Padova 35131 Italy
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7
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Bobone S, De Zotti M, Bortolotti A, Biondi B, Ballano G, Palleschi A, Toniolo C, Formaggio F, Stella L. The fluorescence and infrared absorption probepara-cyanophenylalanine: Effect of labeling on the behavior of different membrane-interacting peptides. Biopolymers 2015; 104:521-32. [DOI: 10.1002/bip.22674] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 04/30/2015] [Accepted: 05/04/2015] [Indexed: 12/18/2022]
Affiliation(s)
- Sara Bobone
- Department of Chemical Sciences and Technologies; University of Rome Tor Vergata; 00133 Rome Italy
| | - Marta De Zotti
- Department of Chemistry; University of Padova; 35131 Padova Italy
| | - Annalisa Bortolotti
- Department of Chemical Sciences and Technologies; University of Rome Tor Vergata; 00133 Rome Italy
| | - Barbara Biondi
- Institute of Biomolecular Chemistry, Padova Unit, CNR; 35131 Padova Italy
| | - Gema Ballano
- Department of Chemistry; University of Padova; 35131 Padova Italy
| | - Antonio Palleschi
- Department of Chemical Sciences and Technologies; University of Rome Tor Vergata; 00133 Rome Italy
| | - Claudio Toniolo
- Department of Chemistry; University of Padova; 35131 Padova Italy
- Institute of Biomolecular Chemistry, Padova Unit, CNR; 35131 Padova Italy
| | - Fernando Formaggio
- Department of Chemistry; University of Padova; 35131 Padova Italy
- Institute of Biomolecular Chemistry, Padova Unit, CNR; 35131 Padova Italy
| | - Lorenzo Stella
- Department of Chemical Sciences and Technologies; University of Rome Tor Vergata; 00133 Rome Italy
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8
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De Zotti M, Ballano G, Jost M, Salnikov ES, Bechinger B, Oancea S, Crisma M, Toniolo C, Formaggio F. Solution synthesis, conformational analysis, and antimicrobial activity of three alamethicin F50/5 analogs bearing a trifluoroacetyl label. Chem Biodivers 2015; 11:1163-91. [PMID: 25146762 DOI: 10.1002/cbdv.201300394] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Indexed: 11/07/2022]
Abstract
We prepared, by solution-phase methods, and fully characterized three analogs of the membrane-active peptaibiotic alamethicin F50/5, bearing a single trifluoroacetyl (Tfa) label at the N-terminus, at position 9 (central region) or at position 19 (C-terminus), and with the three Gln at positions 7, 18, and 19 replaced by Glu(OMe) residues. To add the Tfa label at position 9 or 19, a γ-trifluoroacetylated α,γ-diaminobutyric acid (Dab) residue was incorporated as a replacement for the original Val(9) or Glu(OMe)(19) amino acid. We performed a detailed conformational analysis of the three analogs (using FT-IR absorption, CD, 2D-NMR, and X-ray diffraction), which clearly showed that Tfa labeling does not introduce any dramatic backbone modification in the predominantly α-helical structure of the parent peptaibiotic. The results of an initial solid-state (19)F-NMR study on one of the analogs favor the conclusion that the Tfa group is a very promising reporter for the analysis of peptaibioticmembrane interactions. Finally, we found that the antimicrobial activities of the three newly synthesized analogs depend on the position of the Tfa label in the peptide sequence.
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Affiliation(s)
- Marta De Zotti
- ICB, Padova Unit, CNR, Department of Chemistry, University of Padova, I-35131 Padova.
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9
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Prabhu G, Narendra N, Basavaprabhu B, Panduranga V, Sureshbabu VV. Amino acid fluorides: viable tools for synthesis of peptides, peptidomimetics and enantiopure heterocycles. RSC Adv 2015. [DOI: 10.1039/c4ra16142d] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
This review provides a broad perspective of the uses of amino acid fluorides in the synthesis of peptides and a wide range of other molecules including peptidomimetics, heterocycles and biologically active molecules.
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Affiliation(s)
- Girish Prabhu
- Room No. 109, Peptide Research Laboratory
- Department of Studies in Chemistry
- Central College Campus
- Dr B. R. Ambedkar Veedhi
- Bangalore University
| | - N. Narendra
- Department of Chemistry
- University College of Science
- Tumkur University
- Tumkur-572 103
- India
| | - Basavaprabhu Basavaprabhu
- Room No. 109, Peptide Research Laboratory
- Department of Studies in Chemistry
- Central College Campus
- Dr B. R. Ambedkar Veedhi
- Bangalore University
| | - V. Panduranga
- Room No. 109, Peptide Research Laboratory
- Department of Studies in Chemistry
- Central College Campus
- Dr B. R. Ambedkar Veedhi
- Bangalore University
| | - Vommina V. Sureshbabu
- Room No. 109, Peptide Research Laboratory
- Department of Studies in Chemistry
- Central College Campus
- Dr B. R. Ambedkar Veedhi
- Bangalore University
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10
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Milov AD, Samoilova RI, Tsvetkov YD, Peggion C, Formaggio F, Toniolo C. Peptides on the Surface. PELDOR Data for Spin-Labeled Alamethicin F50/5 Analogues on Organic Sorbent. J Phys Chem B 2014; 118:7085-90. [DOI: 10.1021/jp503691n] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Alexander D. Milov
- V.V.
Voevodsky Institute of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russian Federation
| | - Rimma I. Samoilova
- V.V.
Voevodsky Institute of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russian Federation
| | - Yuri D. Tsvetkov
- V.V.
Voevodsky Institute of Chemical Kinetics and Combustion, 630090 Novosibirsk, Russian Federation
| | - Cristina Peggion
- Institute
of Biomolecular Chemistry, Padova Unit, CNR, Department of Chemistry, University of Padova, 35131 Padova, Italy
| | - Fernando Formaggio
- Institute
of Biomolecular Chemistry, Padova Unit, CNR, Department of Chemistry, University of Padova, 35131 Padova, Italy
| | - Claudio Toniolo
- Institute
of Biomolecular Chemistry, Padova Unit, CNR, Department of Chemistry, University of Padova, 35131 Padova, Italy
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11
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Orlandin A, Formaggio F, Toffoletti A, Peggion C. Cotton functionalized with peptides: characterization and synthetic methods. J Pept Sci 2014; 20:547-53. [DOI: 10.1002/psc.2659] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 04/16/2014] [Accepted: 04/30/2014] [Indexed: 12/18/2022]
Affiliation(s)
- Andrea Orlandin
- ICB, Padova Unit, CNR, Department of Chemistry; University of Padova; via Marzolo 1 35131 Padova Italy
| | - Fernando Formaggio
- ICB, Padova Unit, CNR, Department of Chemistry; University of Padova; via Marzolo 1 35131 Padova Italy
| | - Antonio Toffoletti
- ICB, Padova Unit, CNR, Department of Chemistry; University of Padova; via Marzolo 1 35131 Padova Italy
| | - Cristina Peggion
- ICB, Padova Unit, CNR, Department of Chemistry; University of Padova; via Marzolo 1 35131 Padova Italy
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12
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Ben Haj Salah K, Inguimbert N. Efficient Microwave-Assisted One Shot Synthesis of Peptaibols Using Inexpensive Coupling Reagents. Org Lett 2014; 16:1783-5. [DOI: 10.1021/ol5003253] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Khoubaib Ben Haj Salah
- Université de Perpignan Via Domitia, Centre de Recherche Insulaire
et Observatoire de l’Environnement (CRIOBE) USR CNRS 3278,
Centre de Phytopharmacie, batiment T, 58 avenue P. Alduy, 66860 Perpignan, France
| | - Nicolas Inguimbert
- Université de Perpignan Via Domitia, Centre de Recherche Insulaire
et Observatoire de l’Environnement (CRIOBE) USR CNRS 3278,
Centre de Phytopharmacie, batiment T, 58 avenue P. Alduy, 66860 Perpignan, France
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13
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Bortolus M, De Zotti M, Formaggio F, Maniero AL. Alamethicin in bicelles: Orientation, aggregation, and bilayer modification as a function of peptide concentration. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2620-7. [DOI: 10.1016/j.bbamem.2013.07.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 05/24/2013] [Accepted: 07/08/2013] [Indexed: 10/26/2022]
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14
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Dzuba SA. Structural studies of biological membranes using ESEEM spectroscopy of spin labels and deuterium substitution. J STRUCT CHEM+ 2013. [DOI: 10.1134/s0022476613070019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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15
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Aquila M, Benedusi M, Koch KW, Dell’Orco D, Rispoli G. Divalent cations modulate membrane binding and pore formation of a potent antibiotic peptide analog of alamethicin. Cell Calcium 2013; 53:180-6. [DOI: 10.1016/j.ceca.2012.11.012] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 10/22/2012] [Accepted: 11/19/2012] [Indexed: 11/15/2022]
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16
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Nelissen J, Nuyts K, De Zotti M, Lavigne R, Lamberigts C, De Borggraeve WM. Total synthesis of Septocylindrin B and C-terminus modified analogues. PLoS One 2012; 7:e51708. [PMID: 23284749 PMCID: PMC3527430 DOI: 10.1371/journal.pone.0051708] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 11/05/2012] [Indexed: 11/19/2022] Open
Abstract
The total synthesis is reported of the peptaibol Septocylindrin B which is related to the well documented channel forming peptaibol antibiotic Alamethicin. Several analogues were synthesized with a modified C-terminus, to investigate the SAR of the terminal residue Phaol. All these peptides were tested for their membrane perturbation properties by fluorescent dye leakage assay and for their antibacterial activity.
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Affiliation(s)
- Jo Nelissen
- Molecular Design and Synthesis, Department of Chemistry, University of Leuven, Heverlee, Belgium
| | - Koen Nuyts
- Molecular Design and Synthesis, Department of Chemistry, University of Leuven, Heverlee, Belgium
| | - Marta De Zotti
- Department of Chemistry, University of Padova, Padova, Italy
| | - Rob Lavigne
- Laboratory of Gene Technology, Biosystems Department, University of Leuven, Heverlee, Belgium
| | - Chris Lamberigts
- Laboratory of Gene Technology, Biosystems Department, University of Leuven, Heverlee, Belgium
| | - Wim M. De Borggraeve
- Molecular Design and Synthesis, Department of Chemistry, University of Leuven, Heverlee, Belgium
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17
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Jose RA, De Zotti M, Peggion C, Formaggio F, Toniolo C, De Borggraeve WM. Comparison of distance information in [TOAC(1) , Glu(OMe)(7, 18, 19) ] alamethicin F50/5 from paramagnetic relaxation enhancement measurements with data obtained from an X-ray diffraction-based model. J Pept Sci 2011; 17:377-82. [PMID: 21412956 DOI: 10.1002/psc.1354] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 12/14/2010] [Accepted: 12/15/2010] [Indexed: 11/09/2022]
Abstract
Peptaibol antibiotics are membrane-active linear peptides of fungal origin that are characterized by a high population of the C(α) -tetrasubstituted, strongly helicogenic, α-amino acid, α-aminoisobutyric acid, an N-terminal acetyl group, and a C-terminal 1,2-amino alcohol. Alamethicins (Alms), among the longest peptaibiotics, are a group of closely sequence-related peptides composed of 19 amino acid residues. [TOAC(1) , Glu(OMe)(7, 18, 19) ] Alm and [TOAC(16) , Glu(OMe)(7, 18, 19) ] Alm are synthetic, nitroxide free-radical labeled analogs of [Glu(OMe)(7, 18, 19) ] Alm F50/5. In this work, nitroxide to peptide NH proton distance information obtained from paramagnetic relaxation enhancement (PRE) studies on [TOAC(1) , Glu(OMe)(7, 18, 19) ] Alm is compared with distances derived from an X-ray diffraction-based model. The methodology for PRE determination, as well as the generation of the X-ray diffraction-based model three-dimensional structures, is discussed. The distances obtained from PRE measurements are in close agreement with the information derived from the X-ray diffraction-based model. This finding suggests that this type of information could be implemented as long-range distance restraints in NMR-based structure determination.
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Affiliation(s)
- Rani Alphonsa Jose
- Molecular Design and Synthesis, Department of Chemistry, Katholieke Universiteit Leuven, 3001 Heverlee, Belgium
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18
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Gobbo M, Poloni C, De Zotti M, Peggion C, Biondi B, Ballano G, Formaggio F, Toniolo C. Synthesis, Preferred Conformation, and Membrane Activity of Medium-Length Peptaibiotics: Tylopeptin B. Chem Biol Drug Des 2010; 75:169-81. [DOI: 10.1111/j.1747-0285.2009.00920.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Bartucci R, Guzzi R, Sportelli L, Marsh D. Intramembrane water associated with TOAC spin-labeled alamethicin: electron spin-echo envelope modulation by D2O. Biophys J 2009; 96:997-1007. [PMID: 19186137 DOI: 10.1016/j.bpj.2008.10.024] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Accepted: 10/21/2008] [Indexed: 11/30/2022] Open
Abstract
Alamethicin is a 20-residue, hydrophobic, helical peptide, which forms voltage-sensitive ion channels in lipid membranes. The helicogenic, nitroxyl amino acid TOAC was substituted isosterically for Aib at residue positions 1, 8, or 16 in a F50/5 alamethicin analog to enable EPR studies. Electron spin-echo envelope modulation (ESEEM) spectroscopy was used to investigate the water exposure of TOAC-alamethicin introduced into membranes of saturated or unsaturated diacyl phosphatidylcholines that were dispersed in D2O. Echo-detected EPR spectra were used to assess the degree of assembly of the peptide in the membrane, via the instantaneous diffusion from intermolecular spin-spin interactions. The profile of residue exposure to water differs between membranes of saturated and unsaturated lipids. In monounsaturated dioleoyl phosphatidylcholine, D2O-ESEEM intensities decrease from TOAC(1) to TOAC(8) and TOAC(16) but not uniformly. This is consistent with a transmembrane orientation for the protoassembled state, in which TOAC(16) is located in the bilayer leaflet opposite to that of TOAC(1) and TOAC(8). Relative to the monomer in fluid bilayers, assembled alamethicin is disposed asymmetrically about the bilayer midplane. In saturated dimyristoyl phosphatidylcholine, the D2O-ESEEM intensity is greatest for TOAC(8), indicating a more superficial location for alamethicin, which correlates with the difference in orientation between gel- and fluid-phase membranes found by conventional EPR of TOAC-alamethicin in aligned phosphatidylcholine bilayers. Increasing alamethicin/lipid ratio in saturated phosphatidylcholine shifts the profile of water exposure toward that with unsaturated lipid, consistent with proposals of a critical concentration for switching between the two different membrane-associated states.
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Affiliation(s)
- R Bartucci
- Dipartimento di Fisica and Unità di Recerca Consorzio Nazionale Interuniversitario per le Scienze fisiche della Materia, Università della Calabria, Arcavacata di Rende, Italy
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20
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Salnikov ES, Zotti MD, Formaggio F, Li X, Toniolo C, OʼNeil JDJ, Raap J, Dzuba SA, Bechinger B. Alamethicin Topology in Phospholipid Membranes by Oriented Solid-state NMR and EPR Spectroscopies: a Comparison. J Phys Chem B 2009; 113:3034-42. [DOI: 10.1021/jp8101805] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Evgeniy S. Salnikov
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation, University of Strasbourg/CNRS, UMR7177, Institut de Chimie, 67070 Strasbourg, France, Institute of Biomolecular Chemistry, CNR, Padova Unit, Department of Chemistry, University of Padova, 35131 Padova, Italy, Department of Chemistry, University of Manitoba, Winnipeg, Canada R3T 2N2, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Marta De Zotti
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation, University of Strasbourg/CNRS, UMR7177, Institut de Chimie, 67070 Strasbourg, France, Institute of Biomolecular Chemistry, CNR, Padova Unit, Department of Chemistry, University of Padova, 35131 Padova, Italy, Department of Chemistry, University of Manitoba, Winnipeg, Canada R3T 2N2, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Fernando Formaggio
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation, University of Strasbourg/CNRS, UMR7177, Institut de Chimie, 67070 Strasbourg, France, Institute of Biomolecular Chemistry, CNR, Padova Unit, Department of Chemistry, University of Padova, 35131 Padova, Italy, Department of Chemistry, University of Manitoba, Winnipeg, Canada R3T 2N2, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Xing Li
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation, University of Strasbourg/CNRS, UMR7177, Institut de Chimie, 67070 Strasbourg, France, Institute of Biomolecular Chemistry, CNR, Padova Unit, Department of Chemistry, University of Padova, 35131 Padova, Italy, Department of Chemistry, University of Manitoba, Winnipeg, Canada R3T 2N2, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Claudio Toniolo
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation, University of Strasbourg/CNRS, UMR7177, Institut de Chimie, 67070 Strasbourg, France, Institute of Biomolecular Chemistry, CNR, Padova Unit, Department of Chemistry, University of Padova, 35131 Padova, Italy, Department of Chemistry, University of Manitoba, Winnipeg, Canada R3T 2N2, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Joe D. J. OʼNeil
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation, University of Strasbourg/CNRS, UMR7177, Institut de Chimie, 67070 Strasbourg, France, Institute of Biomolecular Chemistry, CNR, Padova Unit, Department of Chemistry, University of Padova, 35131 Padova, Italy, Department of Chemistry, University of Manitoba, Winnipeg, Canada R3T 2N2, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Jan Raap
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation, University of Strasbourg/CNRS, UMR7177, Institut de Chimie, 67070 Strasbourg, France, Institute of Biomolecular Chemistry, CNR, Padova Unit, Department of Chemistry, University of Padova, 35131 Padova, Italy, Department of Chemistry, University of Manitoba, Winnipeg, Canada R3T 2N2, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Sergei A. Dzuba
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation, University of Strasbourg/CNRS, UMR7177, Institut de Chimie, 67070 Strasbourg, France, Institute of Biomolecular Chemistry, CNR, Padova Unit, Department of Chemistry, University of Padova, 35131 Padova, Italy, Department of Chemistry, University of Manitoba, Winnipeg, Canada R3T 2N2, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Burkhard Bechinger
- Institute of Chemical Kinetics and Combustion, Russian Academy of Sciences, 630090 Novosibirsk, Russian Federation, University of Strasbourg/CNRS, UMR7177, Institut de Chimie, 67070 Strasbourg, France, Institute of Biomolecular Chemistry, CNR, Padova Unit, Department of Chemistry, University of Padova, 35131 Padova, Italy, Department of Chemistry, University of Manitoba, Winnipeg, Canada R3T 2N2, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
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21
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22
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Milov AD, Samoilova RI, Tsvetkov YD, De Zotti M, Toniolo C, Raap J. PELDOR Conformational Analysis of bis-Labeled Alamethicin Aggregated in Phospholipid Vesicles. J Phys Chem B 2008; 112:13469-72. [DOI: 10.1021/jp8046714] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Alexander D. Milov
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090 Russian Federation, Institute of Biomolecular Chemistry, Padova Unit, CNR, Department of Chemistry, University of Padova, 35131 Padova, Italy, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Rimma I. Samoilova
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090 Russian Federation, Institute of Biomolecular Chemistry, Padova Unit, CNR, Department of Chemistry, University of Padova, 35131 Padova, Italy, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Yuri D. Tsvetkov
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090 Russian Federation, Institute of Biomolecular Chemistry, Padova Unit, CNR, Department of Chemistry, University of Padova, 35131 Padova, Italy, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Marta De Zotti
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090 Russian Federation, Institute of Biomolecular Chemistry, Padova Unit, CNR, Department of Chemistry, University of Padova, 35131 Padova, Italy, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Claudio Toniolo
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090 Russian Federation, Institute of Biomolecular Chemistry, Padova Unit, CNR, Department of Chemistry, University of Padova, 35131 Padova, Italy, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
| | - Jan Raap
- Institute of Chemical Kinetics and Combustion, Novosibirsk, 630090 Russian Federation, Institute of Biomolecular Chemistry, Padova Unit, CNR, Department of Chemistry, University of Padova, 35131 Padova, Italy, and Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, 2300 RA Leiden, The Netherlands
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Mayer M, Semetey V, Gitlin I, Yang J, Whitesides GM. Using ion channel-forming peptides to quantify protein-ligand interactions. J Am Chem Soc 2008; 130:1453-65. [PMID: 18179217 DOI: 10.1021/ja077555f] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This paper proposes a method for sensing affinity interactions by triggering disruption of self-assembly of ion channel-forming peptides in planar lipid bilayers. It shows that the binding of a derivative of alamethicin carrying a covalently attached sulfonamide ligand to carbonic anhydrase II (CA II) resulted in the inhibition of ion channel conductance through the bilayer. We propose that the binding of the bulky CA II protein (MW approximately 30 kD) to the ion channel-forming peptides (MW approximately 2.5 kD) either reduced the tendency of these peptides to self-assemble into a pore or extracted them from the bilayer altogether. In both outcomes, the interactions between the protein and the ligand lead to a disruption of self-assembled pores. Addition of a competitive inhibitor, 4-carboxybenzenesulfonamide, to the solution released CA II from the alamethicin-sulfonamide conjugate and restored the current flow across the bilayer by allowing reassembly of the ion channels in the bilayer. Time-averaged recordings of the current over discrete time intervals made it possible to quantify this monovalent ligand binding interaction. This method gave a dissociation constant of approximately 2 microM for the binding of CA II to alamethicin-sulfonamide in the bilayer recording chamber: this value is consistent with a value obtained independently with CA II and a related sulfonamide derivative by isothermal titration calorimetry.
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Affiliation(s)
- Michael Mayer
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
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Backbone dynamics of alamethicin bound to lipid membranes: spin-echo electron paramagnetic resonance of TOAC-spin labels. Biophys J 2007; 94:2698-705. [PMID: 18096632 DOI: 10.1529/biophysj.107.115287] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Alamethicin F50/5 is a hydrophobic peptide that is devoid of charged residues and that induces voltage-dependent ion channels in lipid membranes. The peptide backbone is likely to be involved in the ion conduction pathway. Electron spin-echo spectroscopy of alamethicin F50/5 analogs in which a selected Aib residue (at position n = 1, 8, or 16) is replaced by the TOAC amino-acid spin label was used to study torsional dynamics of the peptide backbone in association with phosphatidylcholine bilayer membranes. Rapid librational motions of limited angular amplitude were observed at each of the three TOAC sites by recording echo-detected spectra as a function of echo delay time, 2tau. Simulation of the time-resolved spectra, combined with conventional EPR measurements of the librational amplitude, shows that torsional fluctuations of the peptide backbone take place on the subnanosecond to nanosecond timescale, with little temperature dependence. Associated fluctuations in polar fields from the peptide could facilitate ion permeation.
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25
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Carpino LA, Abdel-Maksoud AA, Mansour EME, Zewail MA. Segment Coupling to a Highly Hindered N-Terminal, Alamethicin-Related alpha-Aminoisobutyric Acid (Aib) Residue. Tetrahedron Lett 2007; 48:7404-7407. [PMID: 18846198 DOI: 10.1016/j.tetlet.2007.07.215] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
A model [6 + 5] segment coupling process involving a C-terminal valine hexapeptide acid and a resin-attached pentapeptide amide which N-terminated in a hindered Aib unit was examined using a variety of HOAt-derived coupling reagents. Best results were observed with HAPyU in DCM solvent in which loss of configuration amounted to 5.8%.
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Affiliation(s)
- Louis A Carpino
- Department of Chemistry, University of Massachusetts, Amherst MA 01003, USA
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26
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Marsh D, Jost M, Peggion C, Toniolo C. Solvent dependence of the rotational diffusion of TOAC-spin-labeled alamethicin. Chem Biodivers 2007; 4:1269-74. [PMID: 17589865 DOI: 10.1002/cbdv.200790109] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Three derivatives of the hydrophobic, channel-forming peptaibiotic alamethicin (F50/5) have been synthesized, the original Aib residue at position 1, 8, or 16 being replaced with the spin-labeled amino acid TOAC (=2,2,6,6-tetramethylpiperidin-1-oxyl-4-amino-4-carboxylic acid). Electron-paramagnetic-resonance (EPR) spectroscopy was used to characterize the rotational diffusion of these compounds in five isotropic solvents of differing viscosity and polarity, including MeOH, EtOH, PrOH, i-PrOH, and hexanol (HxOH). In MeOH, the labeled alamethicins were found to rotate anisotropically as a monomer (axial ratio a/b=3). In aliphatic alcohols of increasing viscosity (and hydrophobicity), the rotational correlation times progressively increased. Even in HxOH, the (fivefold) increase in correlation time was no greater than the increase in viscosity. We conclude that TOAC-labeled alamethicins remain monomeric in these solvents of relatively high polarity.
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Affiliation(s)
- Derek Marsh
- Max-Planck-Institut für biophysikalische Chemie, Abteilung Spektroskopie, Göttingen, Germany
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27
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Peggion C, Jost M, Baldini C, Formaggio F, Toniolo C. Total syntheses in solution of TOAC-labelled alamethicin F50/5 analogues. Chem Biodivers 2007; 4:1183-99. [PMID: 17589860 DOI: 10.1002/cbdv.200790104] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Total syntheses in solution of a set of four selected analogues of the 19-mer component F50/5 of alamethicin, the most extensively studied among the channel-former peptaibol antibiotics, are planned and reported. All analogues bear three Glu(OMe) residues, replacing the Gln residues at positions 7, 18, and 19 of the naturally occurring compound. Three analogues are mono-labelled with the free-radical-containing amino acid residue TOAC at the strategic positions 1, 8, or 16. The fourth analogue is bis-labelled with the same EPR-active residue at both positions 1 and 16. In the native sequence, all of the positions where TOAC replacements have been introduced are characterized by residues of Aib, the prototype of the class of helicogenic C(alpha)-tetrasubstituted alpha-amino acids. All of the TOAC analogues synthesized exhibit significant membrane-modifying properties.
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Affiliation(s)
- Cristina Peggion
- Institute of Biomolecular Chemistry, Padova Unit, CNR, Department of Chemistry, University of Padova, Padova, Italy
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28
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Stella L, Burattini M, Mazzuca C, Palleschi A, Venanzi M, Coin I, Peggion C, Toniolo C, Pispisa B. Alamethicin interaction with lipid membranes: a spectroscopic study on synthetic analogues. Chem Biodivers 2007; 4:1299-312. [PMID: 17589867 DOI: 10.1002/cbdv.200790111] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Alamethicin (Alm) is one of the most extensively studied membrane-active antibiotic peptides, but several aspects of its mechanism of action are still under debate. In this study, synthetic analogues of natural Alm F50/5 (Alm-N), labeled with a 9H-fluoren-9-yl group at the N- (F-Alm) or C-terminus (Alm-F), were employed to investigate the position and orientation of this peptide in the membrane environment. Depth-dependent fluorescence quenching and polarized ATR-FT-IR experiments demonstrated that, in the absence of a transmembrane potential, Alm inserts its N-terminus into the membrane, while the C-terminus is exposed to the outer aqueous phase. We also found that the peptaibol populates different orientations with respect to the membrane normal. Furthermore, fluorescence resonance-energy transfer (FRET) indicated that no peptide translocation to the inner leaflet of lipid bilayers occurs. The mechanism of action of Alm is discussed on the basis of these findings. Two other Alm analogues, Alm-P and Alm-S, were exploited to investigate the role of specific Alm residues in terms of membrane-perturbing activity. Substitution of two or three Gln (E) residues (the only polar amino acids in the alamethicin sequence) by gamma-methyl glutamate (Glu(OMe)) residues induced marked variations in the aggregation and partition behaviors of the peptaibols, which, in turn, modulate their membrane activity. In particular, substitution of Gln(18) and Gln(19) caused a six-fold increase in membrane-perturbing activity, thus demonstrating that these residues are not essential for the stabilization of Alm pores.
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Affiliation(s)
- Lorenzo Stella
- Dipartimento di Scienze e Tecnologie Chimiche, Università di Roma Tor Vergata, Rome, Italy.
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Leitgeb B, Szekeres A, Manczinger L, Vágvölgyi C, Kredics L. The history of alamethicin: a review of the most extensively studied peptaibol. Chem Biodivers 2007; 4:1027-51. [PMID: 17589875 DOI: 10.1002/cbdv.200790095] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Balázs Leitgeb
- Institute of Biophysics, Biological Research Center of the Hungarian Academy of Sciences, Temesvári krt. 62, Szeged, Hungary
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30
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Peggion C, Jost M, De Borggraeve WM, Crisma M, Formaggio F, Toniolo C. Conformational analysis of TOAC-labelled alamethicin F50/5 analogues. Chem Biodivers 2007; 4:1256-68. [PMID: 17589864 DOI: 10.1002/cbdv.200790108] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In the preceding paper in this issue, we reported the total syntheses in solution of a set of four TOAC-containing analogues of the [L-Glu(OMe)(7,18,19)] F50/5 component of alamethicin, the prototype of peptaibol antibiotics forming channels in the biological membranes. In this article, we have expanded this work to the examination of their preferred conformation in solution by use of a combination of CD, FT-IR absorption, and NMR spectroscopies. The results are strongly in favor of the view that replacement of the Aib residues at positions 1, 8, and 16 with TOAC (both are members of the helicogenic sub-class of C(alpha)-tetrasubstituted alpha-amino acids) does not significantly affect the overwhelmingly populated alpha-helical 3D structure of alamethicin. The X-ray diffraction crystal structure of the N(alpha)-protected, C-terminal, hexapeptide amide segment Z-L-Pro-L-Val-(Aib)(2)-[L-Glu(OMe)](2)-Fol lends further support to our conformational conclusions.
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Affiliation(s)
- Cristina Peggion
- Institute of Biomolecular Chemistry, Padova Unit, CNR, Department of Chemistry, University of Padova, Padova
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31
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Vedovato N, Baldini C, Toniolo C, Rispoli G. Pore-forming properties of alamethicin F50/5 inserted in a biological membrane. Chem Biodivers 2007; 4:1338-46. [PMID: 17589885 DOI: 10.1002/cbdv.200790114] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The pore-forming properties of native and synthetic alamethicins were investigated in photoreceptor rod outer segments (OS) isolated from frog retina, and recorded in whole-cell configuration. The peptaibols were applied (and removed) to (from) the OS within less than 50 ms by means of a computer-controlled micro-perfusion system. Once blocked with light, the main OS endogenous conductance, the OS membrane resistance was >1 GOmega, allowing low-noise and high-resolution recordings. Currents of ca. 700 pA were recorded in symmetric K(+) (100 mM) and Ca(2+) (1 mM), upon applying 1 microM of alamethicin F50/5 or its [L-Glu(OMe)(7,18,19)] analogue to the OS membrane (clamped at -20 mV). In the latter peptide, the Gln residues at positions 7, 18, and 19 were substituted with side-chain esterified Glu residues. For both peptides, the current activated exponentially, with a delay from peptide application, and exponentially returned to zero without any delay, upon removing the peptide from the external solution. The delay as well as the activation (tau(a)) and deactivation (tau(d)) time constants of the current produced by the modified alamethicin were much slower, and the current noise was much larger, with respect to the corresponding values for alamethicin F50/5. Therefore, the above three Gln residues are not a key factor for pore formation, but the [L-Glu(OMe)(7,18,19)] analogue produces larger pores with a lower probability of formation.
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Affiliation(s)
- Natascia Vedovato
- CNISM, Dipartimento di Biologia, Sezione di Fisiologia e Biofisica and Centro di Neuroscienze, Università di Ferrara, Ferrara, Italy
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Milov AD, Samoilova MI, Tsvetkov YD, Jost M, Peggion C, Formaggio F, Crisma M, Toniolo C, Handgraaf JW, Raap J. Supramolecular Structure of Self-Assembling Alamethicin Analog Studied by ESR and PELDOR. Chem Biodivers 2007; 4:1275-98. [PMID: 17589866 DOI: 10.1002/cbdv.200790110] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Three analogs of alamethicin F50/5, labelled with the TOAC (='2,2,6,6-tetramethylpiperidin-1-oxyl-4-amino-4-carboxylic acid') spin label at positions 1 (Alm1), 8 (Alm8), and 16 (Alm16), resp., were studied by Electron-Spin-Resonance (ESR) and Pulsed Electron-Electron Double-Resonance (PELDOR) techniques in solvents of different polarity to investigate the self-assembly of amphipathic helical peptides in membrane-mimicking environments. In polar solvents, alamethicin forms homogeneous solutions. In the weakly polar chloroform/toluene 1 : 1 mixture, however, this peptide forms aggregates that are detectable at 293 K by ESR in liquid solution, as well as by PELDOR in frozen, glassy solution at 77 K. In liquid solution, free alamethicin molecules and their aggregates show rotational-mobility correlation times tau(r) of 0.87 and 5.9 ns, resp. Based on these values and analysis of dipole-dipole interactions of the TOAC labels in the aggregates, as determined by PELDOR, the average number N of alamethicin molecules in the aggregates is estimated to be less than nine. A distance-distribution function between spin labels in the supramolecular aggregate was obtained. This function exhibits two maxima: a broad one at a distance of 3.0 nm, and a wide one at a distance of ca. 7 nm. A molecular-dynamics (MD)-based model of the aggregate, consisting of two parallel tetramers, each composed of four molecules arranged in a 'head-to-tail' fashion, is proposed, accounting for the observed distances and their distribution.
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Affiliation(s)
- Alexander D Milov
- Institute of Chemical Kinetics and Combustion, Novosibirsk, Russian Federation
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Abstract
In this short review article, the effects of covalent tethering of alamethicin molecules on channel-forming behavior are described. Broadly speaking, these chemical modifications have provided insight into all three aspects of channel behavior: the structure of the conducting state, the ion-selectivity and ion-permeation properties, and the voltage dependence. Each of these aspects are discussed in turn.
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Affiliation(s)
- G Andrew Woolley
- Department of Chemistry, University of Toronto, Toronto, ON, Canada.
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Vedovato N, Rispoli G. A novel technique to study pore-forming peptides in a natural membrane. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 36:771-8. [PMID: 17701240 DOI: 10.1007/s00249-007-0152-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2006] [Revised: 02/10/2007] [Accepted: 02/26/2007] [Indexed: 10/23/2022]
Abstract
The biophysical characteristics and the pore formation dynamics of synthetic or naturally occurring peptides forming membrane-spanning channels were investigated by using isolated photoreceptor rod outer segments (OS) recorded in whole-cell configuration. Once blocking the two OS endogenous conductances (the cGMP channels by light and the Na(+):Ca(2+),K(+) exchanger by removing one of the transported ion species from both sides of the membrane, i.e. K(+), Na(+) or Ca(2+)), the OS membrane resistance (R ( m )) was typically larger than 1 GOmega in the presence of 1 mM external Ca(2+). Therefore, any exogenous current could be studied down to the single channel level. The peptides were applied to (and removed from) the extracellular OS side in approximately 50 ms with a computer-controlled microperfusion system, in which every perfusion parameter, as the rate of solution flow, the temporal sequence of solution changes or the number of automatic, self-washing cycles were controlled by a user-friendly interface. This technique was then used to determine the biophysical properties and the pore formation dynamics of antibiotic peptaibols, as the native alamethicin mixture, the synthesized major component of the neutral fraction (F50/5) of alamethicin, and the synthetic trichogin GA IV.
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Affiliation(s)
- Natascia Vedovato
- CNISM, Dipartimento di Biologia ed Evoluzione, Sezione di Fisiologia e Biofisica and Centro di Neuroscienze, Università di Ferrara, via Borsari 46, Ferrara, Italy
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Marsh D, Jost M, Peggion C, Toniolo C. Lipid chain-length dependence for incorporation of alamethicin in membranes: electron paramagnetic resonance studies on TOAC-spin labeled analogs. Biophys J 2007; 92:4002-11. [PMID: 17351010 PMCID: PMC1868974 DOI: 10.1529/biophysj.107.104026] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Alamethicin is a 19-residue hydrophobic peptide, which is extended by a C-terminal phenylalaninol but lacks residues that might anchor the ends of the peptide at the lipid-water interface. Voltage-dependent ion channels formed by alamethicin depend strongly in their characteristics on chain length of the host lipid membranes. EPR spectroscopy is used to investigate the dependence on lipid chain length of the incorporation of spin-labeled alamethicin in phosphatidylcholine bilayer membranes. The spin-label amino acid TOAC is substituted at residue positions n = 1, 8, or 16 in the sequence of alamethicin F50/5 [TOAC(n), Glu(OMe)(7,18,19)]. Polarity-dependent isotropic hyperfine couplings of the three TOAC derivatives indicate that alamethicin assumes approximately the same location, relative to the membrane midplane, in fluid diC(N)PtdCho bilayers with chain lengths ranging from N = 10-18. Residue TOAC(8) is situated closest to the bilayer midplane, whereas TOAC(16) is located farther from the midplane in the hydrophobic core of the opposing lipid leaflet, and TOAC(1) remains in the lipid polar headgroup region. Orientational order parameters indicate that the tilt of alamethicin relative to the membrane normal is relatively small, even at high temperatures in the fluid phase, and increases rather slowly with decreasing chain length (from 13 degrees to 23 degrees for N = 18 and 10, respectively, at 75 degrees C). This is insufficient for alamethicin to achieve hydrophobic matching. Alamethicin differs in its mode of incorporation from other helical peptides for which transmembrane orientation has been determined as a function of lipid chain length.
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Affiliation(s)
- Derek Marsh
- Max-Planck-Institut für biophysikalische Chemie, Abteilung Spektroskopie, 37070 Göttingen, Germany.
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Marsh D, Jost M, Peggion C, Toniolo C. TOAC spin labels in the backbone of alamethicin: EPR studies in lipid membranes. Biophys J 2007; 92:473-81. [PMID: 17056731 PMCID: PMC1751395 DOI: 10.1529/biophysj.106.092775] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2006] [Accepted: 09/14/2006] [Indexed: 11/18/2022] Open
Abstract
Alamethicin is a 19-amino-acid residue hydrophobic peptide that produces voltage-dependent ion channels in membranes. Analogues of the Glu(OMe)(7,18,19) variant of alamethicin F50/5 that are rigidly spin-labeled in the peptide backbone have been synthesized by replacing residue 1, 8, or 16 with 2,2,6,6-tetramethyl-piperidine-1-oxyl-4-amino-4-carboxyl (TOAC), a helicogenic nitroxyl amino acid. Conventional electron paramagnetic resonance spectra are used to determine the insertion and orientation of the TOAC(n) alamethicins in fluid lipid bilayer membranes of dimyristoyl phosphatidylcholine. Isotropic (14)N-hyperfine couplings indicate that TOAC(8) and TOAC(16) are situated in the hydrophobic core of the membrane, whereas the TOAC(1) label resides closer to the membrane surface. Anisotropic hyperfine splittings show that alamethicin is highly ordered in the fluid membranes. Experiments with aligned membranes demonstrate that the principal diffusion axis lies close to the membrane normal, corresponding to a transmembrane orientation. Combination of data from the three spin-labeled positions yields both the dynamic order parameter of the peptide backbone and the intramolecular orientations of the TOAC groups. The latter are compared with x-ray diffraction results from alamethicin crystals. Saturation transfer electron paramagnetic resonance, which is sensitive to microsecond rotational motion, reveals that overall rotation of alamethicin is fast in fluid membranes, with effective correlation times <30 ns. Thus, alamethicin does not form large stable aggregates in fluid membranes, and ionic conductance must arise from transient or voltage-induced associations.
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Affiliation(s)
- Derek Marsh
- Max-Planck-Institut für Biophysikalische Chemie, Abteilung Spektroskopie, Göttingen, Germany.
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