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Exploring Peptaibol's Profile, Antifungal, and Antitumor Activity of Emericellipsin A of Emericellopsis Species from Soda and Saline Soils. Molecules 2022; 27:molecules27051736. [PMID: 35268835 PMCID: PMC8911692 DOI: 10.3390/molecules27051736] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 03/03/2022] [Accepted: 03/04/2022] [Indexed: 11/17/2022] Open
Abstract
Features of the biochemical adaptations of alkaliphilic fungi to exist in extreme environments could promote the production of active antibiotic compounds with the potential to control microorganisms, causing infections associated with health care. Thirty-eight alkaliphilic and alkalitolerant Emericellopsis strains (E. alkalina, E. cf. maritima, E. cf. terricola, Emericellopsis sp.) isolated from different saline soda soils and belonging to marine, terrestrial, and soda soil ecological clades were investigated for emericellipsin A (EmiA) biosynthesis, an antifungal peptaibol previously described for Emericellopsis alkalina. The analysis of the Emericellopsis sp. strains belonging to marine and terrestrial clades from chloride soils revealed another novel form with a mass of 1032.7 Da, defined by MALDI-TOF Ms/Ms spectrometers, as the EmiA lacked a hydroxyl (dEmiA). EmiA displayed strong inhibitory effects on cell proliferation and viability of HCT 116 cells in a dose- and time-dependent manners and induced apoptosis.
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2
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Banerjee R, Sheet T, Banerjee S, Biondi B, Formaggio F, Toniolo C, Peggion C. C α-Methyl-l-valine: A Preferential Choice over α-Aminoisobutyric Acid for Designing Right-Handed α-Helical Scaffolds. Biochemistry 2021; 60:2704-2714. [PMID: 34463474 DOI: 10.1021/acs.biochem.1c00340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In synthetic peptides containing Gly and coded α-amino acids, one of the most common practices to enhance their helical extent is to incorporate a large number of l-Ala residues along with noncoded, strongly foldameric α-aminoisobutyric acid (Aib) units. Earlier studies have established that Aib-based peptides, with propensity for both the 310- and α-helices, have a tendency to form ordered three-dimensional structure that is much stronger than that exhibited by their l-Ala rich counterparts. However, the achiral nature of Aib induces an inherent, equal preference for the right- and left-handed helical conformations as found in Aib homopeptide stretches. This property poses challenges in the analysis of a model peptide helical conformation based on chirospectroscopic techniques like electronic circular dichroism (ECD), a very important tool for assigning secondary structures. To overcome such ambiguity, we have synthesized and investigated a thermally stable 14-mer peptide in which each of the Aib residues of our previously designed and reported analogue ABGY (where B stands for Aib) is replaced by Cα-methyl-l-valine (L-AMV). Analysis of the results described here from complementary ECD and 1H nuclear magnetic resonance spectroscopic techniques in a variety of environments firmly establishes that the L-AMV-containing peptide exhibits a significantly stronger preference compared to that of its Aib parent in terms of conferring α-helical character. Furthermore, being a chiral α-amino acid, L-AMV shows an intrinsic, extremely strong bias for a quite specific (right-handed) screw sense. These findings emphasize the relevance of L-AMV as a more appropriate unit for the design of right-handed α-helical peptide models that may be utilized as conformationally constrained scaffolds.
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Affiliation(s)
| | | | | | - Barbara Biondi
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.,Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| | - Fernando Formaggio
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.,Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| | - Claudio Toniolo
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.,Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
| | - Cristina Peggion
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy.,Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131 Padova, Italy
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3
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Blanár E, Leitgeb B. Studying the helical conformations of aspereline peptides. Chem Biol Drug Des 2021; 97:1029-1037. [PMID: 33638250 DOI: 10.1111/cbdd.13834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 02/15/2021] [Accepted: 02/21/2021] [Indexed: 11/29/2022]
Abstract
Asperelines are short-sequence peptaibol molecules, and these peptides composed of 10 residues were isolated from the Trichoderma asperellum. In our study, a detailed structural characterization was performed on the asperelines by means of molecular dynamics methods. For the aspereline peptides, the occurrence of various secondary structural elements (i.e. β-turns and helical structures) was investigated along their entire sequences. The results derived from the simulated annealing calculations led to the observations that in the case of asperelines, the types I, III and III' β-turn structures, as well as their stabilizing i ← i+3 H-bonds appeared. However, beside the different β-turns, shorter or longer helical structures were also detected. Based on the results obtained by the molecular dynamics simulations, it was concluded that the three-dimensional structure of aspereline peptides could be characterized by helical conformations (i.e. 310 - and α-helix). Nevertheless, on the basis of individual molecular dynamics trajectories, it was observed that the asperelines could adopt not only the right-handed, but also the left-handed helical structures.
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Affiliation(s)
- Eszter Blanár
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
| | - Balázs Leitgeb
- Institute of Biophysics, Biological Research Centre, Szeged, Hungary
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4
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The Emericellipsins A-E from an Alkalophilic Fungus Emericellopsis alkalina Show Potent Activity against Multidrug-Resistant Pathogenic Fungi. J Fungi (Basel) 2021; 7:jof7020153. [PMID: 33669976 PMCID: PMC7924852 DOI: 10.3390/jof7020153] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 02/18/2021] [Accepted: 02/18/2021] [Indexed: 11/17/2022] Open
Abstract
Novel antimicrobial peptides with antifungal and cytotoxic activity were derived from the alkalophilic fungus Emericellopsis alkalina VKPM F1428. We previously reported that this strain produced emericellipsin A (EmiA), which has strong antifungal and cytotoxic properties. Further analyses of the metabolites obtained under a special alkaline medium resulted in the isolation of four new homologous (Emi B-E). In this work, we report the complete primary structure and detailed biological activity for the newly synthesized nonribosomal antimicrobial peptides called emericellipsins B-E. The inhibitory activity of themajor compound, EmiA, against drug-resistant pathogenic fungi was similar to that of amphotericin B (AmpB). At the same time, EmiA had no hemolytic activity towards human erythrocytes. In addition, EmiA demonstrated low cytotoxic activity towards the normal HPF line, but possessed cancer selectivity to the K-562 and HCT-116 cell lines. Emericillipsins from the alkalophilic fungus Emericellopsis alkaline are promising treatment alternatives to licensed antifungal drugs for invasive mycosis therapy, especially for multidrug-resistant aspergillosis and cryptococcosis.
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5
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Baranova AA, Georgieva ML, Bilanenko EN, Andreev YA, Rogozhin EA, Sadykova VS. Antimicrobial potential of alkalophilic micromycetes Emericellopsis alkalina. APPL BIOCHEM MICRO+ 2017. [DOI: 10.1134/s0003683817060035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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6
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Gessmann R, Axford D, Brückner H, Berg A, Petratos K. A natural, single-residue substitution yields a less active peptaibiotic: the structure of bergofungin A at atomic resolution. Acta Crystallogr F Struct Biol Commun 2017; 73:95-100. [PMID: 28177320 PMCID: PMC5297930 DOI: 10.1107/s2053230x17001236] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 01/24/2017] [Indexed: 11/11/2022] Open
Abstract
Bergofungin is a peptide antibiotic that is produced by the ascomycetous fungus Emericellopsis donezkii HKI 0059 and belongs to peptaibol subfamily 2. The crystal structure of bergofungin A has been determined and refined to 0.84 Å resolution. This is the second crystal structure of a natural 15-residue peptaibol, after that of samarosporin I. The amino-terminal phenylalanine residue in samarosporin I is exchanged to a valine residue in bergofungin A. According to agar diffusion tests, this results in a nearly inactive antibiotic peptide compared with the moderately active samarosporin I. Crystals were obtained from methanol solutions of purified bergofungin mixed with water. Although there are differences in the intramolecular hydrogen-bonding scheme of samarosporin I, the overall folding is very similar for both peptaibols, namely 310-helical at the termini and α-helical in the middle of the molecules. Bergofungin A and samarosporin I molecules are arranged in a similar way in both lattices. However, the packing of bergofungin A exhibits a second solvent channel along the twofold axis. This latter channel occurs in the vicinity of the N-terminus, where the natural substitution resides.
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Affiliation(s)
| | - Danny Axford
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - Hans Brückner
- Department of Food Science, Institute of Nutritional Science, Research Center for BioSystems, Land Use and Nutrition (IFZ), Heinrich-Buff-Ring 26-32, 65392 Giessen, Germany
| | - Albrecht Berg
- Innovent e.V., Prüssingstrasse 27B, 07745 Jena, Germany
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Pike SJ, Jones JE, Raftery J, Clayden J, Webb SJ. Helical peptaibol mimics are better ionophores when racemic than when enantiopure. Org Biomol Chem 2016; 13:9580-4. [PMID: 26327434 DOI: 10.1039/c5ob01652e] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Helical peptide foldamers rich in α-aminoisobutyric acid (Aib) act as peptaibol-mimicking ionophores in the phospholipid bilayers of artificial vesicles. Racemic samples of these foldamers are more active than their enantiopure counterparts, which was attributed to differing propensities to form aggregates with crystal-like features in the bilayer.
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Affiliation(s)
- Sarah J Pike
- School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
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8
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Milov AD, Tsvetkov YD, Bortolus M, Maniero AL, Gobbo M, Toniolo C, Formaggio F. Synthesis and conformational properties of a TOAC doubly spin-labeled analog of the medium-length, membrane active peptaibiotic ampullosporin a as revealed by cd, fluorescence, and EPR spectroscopies. Biopolymers 2014; 102:40-8. [DOI: 10.1002/bip.22362] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/10/2013] [Accepted: 07/12/2013] [Indexed: 11/10/2022]
Affiliation(s)
- Alexander D. Milov
- Institute of Chemical Kinetics and Combustion; Novosibirsk 630090 Russian Federation
| | - Yuri D. Tsvetkov
- Institute of Chemical Kinetics and Combustion; Novosibirsk 630090 Russian Federation
| | - Marco Bortolus
- Department of Chemical Sciences; University of Padova; 35131 Padova Italy
| | - Anna Lisa Maniero
- Department of Chemical Sciences; University of Padova; 35131 Padova Italy
| | - Marina Gobbo
- Department of Chemical Sciences; University of Padova; 35131 Padova Italy
- Institute of Biomolecular Chemistry; Padova Unit, CNR 35131 Padova Italy
| | - Claudio Toniolo
- Department of Chemical Sciences; University of Padova; 35131 Padova Italy
- Institute of Biomolecular Chemistry; Padova Unit, CNR 35131 Padova Italy
| | - Fernando Formaggio
- Department of Chemical Sciences; University of Padova; 35131 Padova Italy
- Institute of Biomolecular Chemistry; Padova Unit, CNR 35131 Padova Italy
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9
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Orcel U, De Poli M, De Zotti M, Clayden J. The N-Terminal Nonapeptide of Cephaibols A and C: A Naturally Occurring Example of Mismatched Helical Screw-Sense Control. Chemistry 2013; 19:16357-65. [DOI: 10.1002/chem.201302648] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Indexed: 12/14/2022]
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10
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Attempts toward the Synthesis of the Peptaibol Antiamoebin by Using the ‘Azirine/Oxazolone Method’. Chem Biodivers 2013; 10:920-41. [DOI: 10.1002/cbdv.201200386] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Indexed: 11/07/2022]
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11
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Shenkarev ZO, Paramonov AS, Lyukmanova EN, Gizatullina AK, Zhuravleva AV, Tagaev AA, Yakimenko ZA, Telezhinskaya IN, Kirpichnikov MP, Ovchinnikova TV, Arseniev AS. Peptaibol Antiamoebin I: Spatial Structure, Backbone Dynamics, Interaction with Bicelles and Lipid-Protein Nanodiscs, and Pore Formation in Context of Barrel-Stave Model. Chem Biodivers 2013; 10:838-63. [DOI: 10.1002/cbdv.201200421] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Indexed: 11/12/2022]
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12
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Gessmann R, Axford D, Evans G, Brückner H, Petratos K. The crystal structure of samarosporin I at atomic resolution. J Pept Sci 2012; 18:678-84. [PMID: 23019149 DOI: 10.1002/psc.2454] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Revised: 08/24/2012] [Accepted: 08/27/2012] [Indexed: 01/24/2023]
Abstract
The atomic resolution structures of samarosporin I have been determined at 100 and 293 K. This is the first crystal structure of a natural 15-residue peptaibol. The amino acid sequence in samarosporin I is identical to emerimicin IV and stilbellin I. Samarosporin is a peptide antibiotic produced by the ascomycetous fungus Samarospora rostrup and belongs to peptaibol subfamily 2. The structures at both temperatures are very similar to each other adopting mainly a 3₁₀-helical and a minor fraction of α-helical conformation. The helices are significantly bent and packed in an antiparallel fashion in the centered monoclinic lattice leaving among them an approximately 10-Å channel extending along the crystallographic twofold axis. Only two ordered water molecules per peptide molecule were located in the channel. Comparisons have been carried out with crystal structures of subfamily 2 16-residue peptaibols antiamoebin and cephaibols. The repercussion of the structural analysis of samarosporin on membrane function is discussed.
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13
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De Zotti M, Biondi B, Crisma M, Hjørringgaard CU, Berg A, Brückner H, Toniolo C. Isovaline in naturally occurring peptides: A nondestructive methodology for configurational assignment. Biopolymers 2011; 98:36-49. [DOI: 10.1002/bip.21679] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2011] [Revised: 05/03/2011] [Accepted: 05/10/2011] [Indexed: 11/08/2022]
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14
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De Zotti M, Biondi B, Peggion C, Park Y, Hahm KS, Formaggio F, Toniolo C. Synthesis, preferred conformation, protease stability, and membrane activity of heptaibin, a medium-length peptaibiotic. J Pept Sci 2011; 17:585-94. [PMID: 21495119 DOI: 10.1002/psc.1364] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Accepted: 01/18/2011] [Indexed: 11/11/2022]
Abstract
The medium-length peptaibiotics are characterized by a primary structure of 14-16 amino acid residues. Despite the interesting antibiotic and antifungal properties exhibited by these membrane-active peptides, their exact mechanism of action is still unknown. Here, we present our results on heptaibin, a 14-amino acid peptaibiotic found to exhibit antimicrobial activity against Staphylococcus aureus. We carried out the very challenging synthesis of heptaibin on solid phase and a detailed conformational analysis in solution. The peptaibiotic is folded in a mixed 3₁₀-/α-helix conformation which exhibits a remarkable amphiphilic character. We also find that it is highly stable toward degradation by proteolytic enzymes and nonhemolytic. Finally, fluorescence leakage experiments using small unilamellar vesicles of three different compositions revealed that heptaibin, although uncharged, is a selective compound for permeabilization of model membranes mimicking the overall negatively charged surface of Gram-positive bacteria. This latter finding is in agreement with the originally published antimicrobial activity data.
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Affiliation(s)
- Marta De Zotti
- ICB, Padova Unit, CNR, Department of Chemistry, University of Padova, via Marzolo 1, 35131 Padova, Italy.
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Structure and alignment of the membrane-associated peptaibols ampullosporin A and alamethicin by oriented 15N and 31P solid-state NMR spectroscopy. Biophys J 2010; 96:86-100. [PMID: 18835909 DOI: 10.1529/biophysj.108.136242] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Accepted: 09/03/2008] [Indexed: 11/18/2022] Open
Abstract
Ampullosporin A and alamethicin are two members of the peptaibol family of antimicrobial peptides. These compounds are produced by fungi and are characterized by a high content of hydrophobic amino acids, and in particular the alpha-tetrasubstituted amino acid residue ?-aminoisobutyric acid. Here ampullosporin A and alamethicin were uniformly labeled with (15)N, purified and reconstituted into oriented phophatidylcholine lipid bilayers and investigated by proton-decoupled (15)N and (31)P solid-state NMR spectroscopy. Whereas alamethicin (20 amino acid residues) adopts transmembrane alignments in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) or 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) membranes the much shorter ampullosporin A (15 residues) exhibits comparable configurations only in thin membranes. In contrast the latter compound is oriented parallel to the membrane surface in 1,2-dimyristoleoyl-sn-glycero-3-phosphocholine and POPC bilayers indicating that hydrophobic mismatch has a decisive effect on the membrane topology of these peptides. Two-dimensional (15)N chemical shift -(1)H-(15)N dipolar coupling solid-state NMR correlation spectroscopy suggests that in their transmembrane configuration both peptides adopt mixed alpha-/3(10)-helical structures which can be explained by the restraints imposed by the membranes and the bulky alpha-aminoisobutyric acid residues. The (15)N solid-state NMR spectra also provide detailed information on the helical tilt angles. The results are discussed with regard to the antimicrobial activities of the peptides.
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Salnikov E, Bertani P, Raap J, Bechinger B. Analysis of the amide (15)N chemical shift tensor of the C(alpha) tetrasubstituted constituent of membrane-active peptaibols, the alpha-aminoisobutyric acid residue, compared to those of di- and tri-substituted proteinogenic amino acid residues. JOURNAL OF BIOMOLECULAR NMR 2009; 45:373-387. [PMID: 19823773 DOI: 10.1007/s10858-009-9380-5] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Accepted: 09/11/2009] [Indexed: 05/28/2023]
Abstract
In protein NMR spectroscopy the chemical shift provides important information for the assignment of residues and a first structural evaluation of dihedral angles. Furthermore, angular restraints are obtained from oriented samples by solution and solid-state NMR spectroscopic approaches. Whereas the anisotropy of chemical shifts, quadrupolar couplings and dipolar interactions have been used to determine the structure, dynamics and topology of oriented membrane polypeptides using solid-state NMR spectroscopy similar concepts have been introduced to solution NMR through the measurements of residual dipolar couplings. The analysis of (15)N chemical shift spectra depends on the accuracy of the chemical shift tensors. When investigating alamethicin and other peptaibols, i.e. polypeptides rich in alpha-aminoisobutyric acid (Aib), the (15)N chemical shift tensor of this C(alpha)-tetrasubstituted amino acid exhibits pronounced differences when compared to glycine, alanine and other proteinogenic residues. Here we present an experimental investigation on the (15)N amide Aib tensor of N-acetyl-Aib-OH and for the Aib residues within peptaibols. Furthermore, a statistical analysis of the tensors published for di- (glycine) and tri-substituted residues has been performed, where for the first time the published data sets are compiled using a common reference. The size of the isotropic chemical shift and main tensor elements follows the order di- < tri- < tetra-substituted amino acids. A (15)N chemical shift-(1)H-(15)N dipolar coupling correlation NMR spectrum of alamethicin is used to evaluate the consequences of variations in the main tensor elements for the structural analysis of this membrane peptide.
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Affiliation(s)
- Evgeniy Salnikov
- Institut de Chimie, Université de Strasbourg/CNRS, UMR7177, Strasbourg, France
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17
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Shenkarev ZO, Lyukmanova EN, Solozhenkin OI, Gagnidze IE, Nekrasova OV, Chupin VV, Tagaev AA, Yakimenko ZA, Ovchinnikova TV, Kirpichnikov MP, Arseniev AS. Lipid-protein nanodiscs: possible application in high-resolution NMR investigations of membrane proteins and membrane-active peptides. BIOCHEMISTRY (MOSCOW) 2009; 74:756-65. [PMID: 19747096 DOI: 10.1134/s0006297909070086] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
High-resolution NMR is shown to be applicable for investigation of membrane proteins and membrane-active peptides embedded into lipid-protein nanodiscs (LPNs). (15)N-Labeled K+-channel from Streptomyces lividans (KcsA) and the antibiotic antiamoebin I from Emericellopsis minima (Aam-I) were embedded in LPNs of different lipid composition. Formation of stable complexes undergoing isotropic motion in solution was confirmed by size-exclusion chromatography and (31)P-NMR spectroscopy. The 2D 1H-(15)N-correlation spectra were recorded for KcsA in the complex with LPN containing DMPC and for Aam-I in LPNs based on DOPG, DLPC, DMPC, and POPC. The spectra recorded were compared with those in detergent-containing micelles and small bicelles commonly used in high-resolution NMR spectroscopy of membrane proteins. The spectra recorded in LPN environments demonstrated similar signal dispersion but significantly increased (1)H(N) line width. The spectra of Aam-I embedded in LPNs containing phosphatidylcholine showed significant selective line broadening, thus suggesting exchange process(es) between several membrane-bound states of the peptide. (15)N relaxation rates were measured to obtain the effective rotational correlation time of the Aam-I molecule. The obtained value (approximately 40 nsec at 45 degrees C) is indicative of additional peptide motions within the Aam-I/LPN complex.
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Affiliation(s)
- Z O Shenkarev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
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18
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Kulp J, Clark T. Engineering a β-Helical d,l-Peptide for Folding in Polar Media. Chemistry 2009; 15:11867-77. [DOI: 10.1002/chem.200901129] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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19
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Banerjee R, Chattopadhyay S, Basu G. Conformational preferences of a short Aib/Ala-based water-soluble peptide as a function of temperature. Proteins 2009; 76:184-200. [PMID: 19137603 DOI: 10.1002/prot.22337] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The amino acid Aib predisposes a peptide to be helical with context-dependent preference for either 3(10)- or alpha- or a mixed helical conformation. Short peptides also show an inherent tendency to be unfolded. To characterize helical and unfolded states adopted by water-soluble Aib-containing peptides, the conformational preference of Ac-Ala-Aib-Ala-Lys-Ala-Aib-Lys-Ala-Lys-Ala-Aib-Tyr-NH(2) was determined by CD, NMR and MD simulations as a function of temperature. Temperature-dependent CD data indicated the contribution of two major components, each an admixture of helical and extended/polyproline II structures. Both right- and left-handed helical conformations were detected from deconvolution of CD data and (13)C NMR experiments. The presence of a helical backbone, more pronounced at the N-terminal, and a temperature-induced shift in alpha-helix/3(10)-helix equilibrium, more pronounced at the C-terminal, emerged from NMR data. Starting from polyproline II, the N-terminal of the peptide folded into a helical backbone in MD simulations within 5 ns at 60 degrees C. Longer simulations showed a mixed-helical backbone to be stable over the entire peptide at 5 degrees C while at 60 degrees C the mixed-helix was either stable at the N-terminus or occurred in short stretches through out the peptide, along with a significant population of polyproline II. Our results point towards conformational heterogeneity of water-soluble Aib-based peptide helices and the associated subtleties. The problem of analyzing CD and NMR data of both left- and right-handed helices are discussed, especially the validity of the ellipticity ratio [theta](222)/[theta](207), as a reporter of alpha-/3(10)- population ratio, in right- and left-handed helical mixtures.
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Affiliation(s)
- Raja Banerjee
- Department of Biotechnology, West Bengal University of Technology, Kolkata 700064, India.
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20
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Brun K, Linden A, Heimgartner H. Synthesis and Conformational Analysis of Pentapeptides Containing Enantiomerically Pure 2,2-Disubstituted Glycines. Helv Chim Acta 2008. [DOI: 10.1002/hlca.200890057] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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21
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Lyukmanova EN, Shenkarev ZO, Paramonov AS, Sobol AG, Ovchinnikova TV, Chupin VV, Kirpichnikov MP, Blommers MJJ, Arseniev AS. Lipid−Protein Nanoscale Bilayers: A Versatile Medium for NMR Investigations of Membrane Proteins and Membrane-Active Peptides. J Am Chem Soc 2008; 130:2140-1. [DOI: 10.1021/ja0777988] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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