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Agadi N, Maity A, Jha AK, Chakrabarti R, Kumar A. Distinct mode of membrane interaction and disintegration by diverse class of antimicrobial peptides. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:184047. [PMID: 36100074 DOI: 10.1016/j.bbamem.2022.184047] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 08/18/2022] [Accepted: 09/06/2022] [Indexed: 12/29/2022]
Abstract
The exploitation of conventional antibiotics in conjunction with the adeptness of microbes has led to the emergence of multi-drug-resistant pathogens. This has posed a severe threat to combating life-threatening infectious diseases. Antimicrobial peptides (AMP), which are considered to be the first line of defense in all living organisms, are being developed for therapeutic use. Herein, we determined the NMR solution structure of Rhesus macaque Myeloid Alpha Defensin-4 (RMAD4), a defensin AMP. Additionally, the distinct modes of membrane perturbation for two structurally dissimilar classes of AMPs was studied using biophysical methods namely, Solid-state 31P NMR, DSC and cryo-TEM. The cathelicidin - Bovine myeloid antimicrobial peptide (BMAP-28 (1-18)), which adopts a helical conformation, and the defensin RMAD4 peptide that natively folds to form β-sheets appeared to engage differently with the bacterial membrane. The helical BMAP-28 (1-18) peptide initiates lipid segregation and membrane thinning followed by pore formation, while the β-stranded RMAD4 peptide demonstrates fragmentation of the bilayer by the carpet or detergent-like mechanism of action. Molecular dynamics studies sufficiently corroborated these findings. The structure and mechanism of action of the AMPs studied using experimental and computational approaches are believed to help in providing a platform for the rational design of new competent and cost-effective antimicrobial peptides for therapeutic applications.
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Affiliation(s)
- Nutan Agadi
- Centre for Research in Nanotechnology and Science (CRNTS), Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Atanu Maity
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Akash Kumar Jha
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Rajarshi Chakrabarti
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Ashutosh Kumar
- Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
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The Electrostatic Basis of Diacylglycerol Pyrophosphate—Protein Interaction. Cells 2022; 11:cells11020290. [PMID: 35053406 PMCID: PMC8774204 DOI: 10.3390/cells11020290] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 01/04/2022] [Accepted: 01/07/2022] [Indexed: 01/08/2023] Open
Abstract
Diacylglycerol pyrophosphate (DGPP) is an anionic phospholipid formed in plants, yeast, and parasites under multiple stress stimuli. It is synthesized by the phosphorylation action of phosphatidic acid (PA) kinase on phosphatidic acid, a signaling lipid with multifunctional properties. PA functions in the membrane through the interaction of its negatively charged phosphomonoester headgroup with positively charged proteins and ions. DGPP, like PA, can interact electrostatically via the electrostatic-hydrogen bond switch mechanism but differs from PA in its overall charge and shape. The formation of DGPP from PA alters the physicochemical properties as well as the structural dynamics of the membrane. This potentially impacts the molecular and ionic binding of cationic proteins and ions with the DGPP enriched membrane. However, the results of these important interactions in the stress response and in DGPP’s overall intracellular function is unknown. Here, using 31P MAS NMR, we analyze the effect of the interaction of low DGPP concentrations in model membranes with the peptides KALP23 and WALP23, which are flanked by positively charged Lysine and neutral Tryptophan residues, respectively. Our results show a significant effect of KALP23 on the charge of DGPP as compared to WALP23. There was, however, no significant effect on the charge of the phosphomonoester of DGPP due to the interaction with positively charged lipids, dioleoyl trimethylammonium propane (DOTAP) and dioleoyl ethyl-phosphatidylcholine (EtPC). Divalent calcium and magnesium cations induce deprotonation of the DGPP headgroup but showed no noticeable differences on DGPP’s charge. Our results lead to a novel model for DGPP—protein interaction.
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Investigating the action of the microalgal pigment marennine on Vibrio splendidus by in vivo 2H and 31P solid-state NMR. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183642. [PMID: 34000261 DOI: 10.1016/j.bbamem.2021.183642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 04/28/2021] [Accepted: 05/04/2021] [Indexed: 11/21/2022]
Abstract
This work investigates the potential probiotic effect of marennine - a natural pigment produced by the diatom Haslea ostrearia - on Vibrio splendidus. These marine bacteria are often considered a threat for aquaculture; therefore, chemical antibiotics can be required to reduce bacterial outbreaks. In vivo2H solid-state NMR was used to probe the effects of marennine on the bacterial membrane in the exponential and stationary phases. Comparisons were made with polymyxin B (PxB) - an antibiotic used in aquaculture and known to interact with Gram(-) bacteria membranes. We also investigated the effect of marennine using 31P solid-state NMR on model membranes. Our results show that marennine has little effect on phospholipid headgroups dynamics, but reduces the acyl chain fluidity. Our data suggest that the two antimicrobial agents perturb V. splendidus membranes through different mechanisms. While PxB would alter the bacterial outer and inner membranes, marennine would act through a membrane stiffening mechanism, without affecting the bilayer integrity. Our study proposes this microalgal pigment, which is harmless for humans, as a potential treatment against vibriosis.
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Effects of Hydrophobic Amino Acid Substitutions on Antimicrobial Peptide Behavior. Probiotics Antimicrob Proteins 2019; 10:408-419. [PMID: 29103131 DOI: 10.1007/s12602-017-9345-z] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Antimicrobial peptides (AMPs) are naturally occurring components of the immune system that act against bacteria in a variety of organisms throughout the evolutionary hierarchy. There have been many studies focused on the activity of AMPs using biophysical and microbiological techniques; however, a clear and predictive mechanism toward determining if a peptide will exhibit antimicrobial activity is still elusive, in addition to the fact that the mechanism of action of AMPs has been shown to vary between peptides, targets, and experimental conditions. Nonetheless, the majority of AMPs contain hydrophobic amino acids to facilitate partitioning into bacterial membranes and a net cationic charge to promote selective binding to the anionic surfaces of bacteria over the zwitterionic host cell surfaces. This study explores the role of hydrophobic amino acids using the peptide C18G as a model system. These changes were evaluated for the effects on antimicrobial activity, peptide-lipid interactions using Trp fluorescence spectroscopy, peptide secondary structure formation, and bacterial membrane permeabilization. The results show that while secondary structure formation was not significantly impacted by the substitutions, antibacterial activity and binding to model lipid membranes were well correlated. The variants containing Leu or Phe as the sole hydrophobic groups bound bilayers with highest affinity and were most effective at inhibiting bacterial growth. Peptides with Ile exhibited intermediate behavior while those with Val or α-aminoisobutyric acid (Aib) showed poor binding and activity. The Leu, Phe, and Ile peptides demonstrated a clear preference for anionic bilayers, exhibiting significant emission spectrum shifts upon binding. Similarly, the Leu, Phe, and Ile peptides demonstrated greater ability to disrupt lipid vesicles and bacterial membranes. In total, the data indicate that hydrophobic moieties in the AMP sequence play a significant role in the binding and ability of the peptide to exhibit antibacterial activity.
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Reid KA, Davis CM, Dyer RB, Kindt JT. Binding, folding and insertion of a β-hairpin peptide at a lipid bilayer surface: Influence of electrostatics and lipid tail packing. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:792-800. [PMID: 29291379 DOI: 10.1016/j.bbamem.2017.12.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 12/12/2017] [Accepted: 12/25/2017] [Indexed: 12/11/2022]
Abstract
Antimicrobial peptides (AMPs) act as host defenses against microbial pathogens. Here we investigate the interactions of SVS-1 (KVKVKVKVdPlPTKVKVKVK), an engineered AMP and anti-cancer β-hairpin peptide, with lipid bilayers using spectroscopic studies and atomistic molecular dynamics simulations. In agreement with literature reports, simulation and experiment show preferential binding of SVS-1 peptides to anionic over neutral bilayers. Fluorescence and circular dichroism studies of a Trp-substituted SVS-1 analogue indicate, however, that it will bind to a zwitterionic DPPC bilayer under high-curvature conditions and folds into a hairpin. In bilayers formed from a 1:1 mixture of DPPC and anionic DPPG lipids, curvature and lipid fluidity are also observed to promote deeper insertion of the fluorescent peptide. Simulations using the CHARMM C36m force field offer complementary insight into timescales and mechanisms of folding and insertion. SVS-1 simulated at an anionic mixed POPC/POPG bilayer folded into a hairpin over a microsecond, the final stage in folding coinciding with the establishment of contact between the peptide's valine sidechains and the lipid tails through a "flip and dip" mechanism. Partial, transient folding and superficial bilayer contact are seen in simulation of the peptide at a zwitterionic POPC bilayer. Only when external surface tension is applied does the peptide establish lasting contact with the POPC bilayer. Our findings reveal the influence of disruption to lipid headgroup packing (via curvature or surface tension) on the pathway of binding and insertion, highlighting the collaborative effort of electrostatic and hydrophobic interactions on interaction of SVS-1 with lipid bilayers.
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Affiliation(s)
- Keon A Reid
- Department of Chemistry, Emory University, 201 Dowman Drive, Atlanta, GA 30322, United States
| | - Caitlin M Davis
- Department of Chemistry, Emory University, 201 Dowman Drive, Atlanta, GA 30322, United States; Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - R Brian Dyer
- Department of Chemistry, Emory University, 201 Dowman Drive, Atlanta, GA 30322, United States
| | - James T Kindt
- Department of Chemistry, Emory University, 201 Dowman Drive, Atlanta, GA 30322, United States.
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Li J, Koh JJ, Liu S, Lakshminarayanan R, Verma CS, Beuerman RW. Membrane Active Antimicrobial Peptides: Translating Mechanistic Insights to Design. Front Neurosci 2017; 11:73. [PMID: 28261050 PMCID: PMC5306396 DOI: 10.3389/fnins.2017.00073] [Citation(s) in RCA: 346] [Impact Index Per Article: 49.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 01/31/2017] [Indexed: 01/10/2023] Open
Abstract
Antimicrobial peptides (AMPs) are promising next generation antibiotics that hold great potential for combating bacterial resistance. AMPs can be both bacteriostatic and bactericidal, induce rapid killing and display a lower propensity to develop resistance than do conventional antibiotics. Despite significant progress in the past 30 years, no peptide antibiotic has reached the clinic yet. Poor understanding of the action mechanisms and lack of rational design principles have been the two major obstacles that have slowed progress. Technological developments are now enabling multidisciplinary approaches including molecular dynamics simulations combined with biophysics and microbiology toward providing valuable insights into the interactions of AMPs with membranes at atomic level. This has led to increasingly robust models of the mechanisms of action of AMPs and has begun to contribute meaningfully toward the discovery of new AMPs. This review discusses the detailed action mechanisms that have been put forward, with detailed atomistic insights into how the AMPs interact with bacterial membranes. The review further discusses how this knowledge is exploited toward developing design principles for novel AMPs. Finally, the current status, associated challenges, and future directions for the development of AMP therapeutics are discussed.
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Affiliation(s)
- Jianguo Li
- Ocular Chemistry and Anti-Infectives, Singapore Eye Research InstituteSingapore, Singapore
- Agency for Science, Technology and Research (ASTAR), Bioinformatics InstituteSingapore, Singapore
- Duke-NUS Graduate Medical School, SRP Neuroscience and BDSingapore, Singapore
| | - Jun-Jie Koh
- Ocular Chemistry and Anti-Infectives, Singapore Eye Research InstituteSingapore, Singapore
| | - Shouping Liu
- Ocular Chemistry and Anti-Infectives, Singapore Eye Research InstituteSingapore, Singapore
| | | | - Chandra S. Verma
- Ocular Chemistry and Anti-Infectives, Singapore Eye Research InstituteSingapore, Singapore
- Agency for Science, Technology and Research (ASTAR), Bioinformatics InstituteSingapore, Singapore
- Department of Biological Sciences, National University of SingaporeSingapore, Singapore
- School of Biological Sciences, Nanyang Technological UniversitySingapore, Singapore
| | - Roger W. Beuerman
- Ocular Chemistry and Anti-Infectives, Singapore Eye Research InstituteSingapore, Singapore
- Duke-NUS Graduate Medical School, SRP Neuroscience and BDSingapore, Singapore
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7
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Yepuri NR, Darwish TA, Krause-Heuer AM, Leung AE, Delhom R, Wacklin HP, Holden PJ. Synthesis of Perdeuterated 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine ([D 82 ]POPC) and Characterisation of Its Lipid Bilayer Membrane Structure by Neutron Reflectometry. Chempluschem 2016; 81:315-321. [PMID: 31968790 DOI: 10.1002/cplu.201500452] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Indexed: 11/05/2022]
Abstract
1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), an unsaturated acyl chain containing lipid, is often the predominant lipid in eukaryotic cell membranes in which it is crucial for the fluidity of membranes under physiological conditions. Commercially available, partially deuterated [D31 ]1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine ([D31 ]POPC) does not provide sufficient isotopic contrast for detailed structural studies of multicomponent membranes through neutron techniques. Herein, a relatively straightforward and generic chemical deuteration method is discussed for the asymmetric synthesis of perdeuterated [D31 ]1-palmitoyl-[D33 ]2-oleoyl-sn-[D5 ]glycero-[D13 ]3-phosphocholine ([D82 ]POPC) that also allows selective deuteration of any of its constituent groups. Neutron reflectivity of a [D82 ]POPC-supported bilayer was used to experimentally determine the neutron scattering length density profile of the lipid. The acyl chains of [D82 ]POPC are closely contrast-matched to heavy water, whereas the very high scattering length density of the deuterated glycerophosphocholine head groups provides good contrast to membrane-binding agents in both deuterated and non-deuterated solvent environments.
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Affiliation(s)
- Nageshwar R Yepuri
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Tamim A Darwish
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Anwen M Krause-Heuer
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Anna E Leung
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Robin Delhom
- European Spallation Source ERIC, Box 176, 22100, Lund, Sweden.,Institut Laue Langevin (ILL), 71 av des Martyrs, 38042, Grenoble, France
| | - Hanna P Wacklin
- European Spallation Source ERIC, Box 176, 22100, Lund, Sweden.,Division of Physical Chemistry, Department of Chemistry, Lund Universit, P.O. Box 124, 22100, Lund, Sweden
| | - Peter J Holden
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
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8
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Zhang L, Liu L, Maltsev S, Lorigan GA, Dabney-Smith C. Investigating the interaction between peptides of the amphipathic helix of Hcf106 and the phospholipid bilayer by solid-state NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:413-8. [PMID: 24144541 DOI: 10.1016/j.bbamem.2013.10.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 10/01/2013] [Accepted: 10/04/2013] [Indexed: 12/15/2022]
Abstract
The chloroplast twin arginine translocation (cpTat) system transports highly folded precursor proteins into the thylakoid lumen using the protonmotive force as its only energy source. Hcf106, as one of the core components of the cpTat system, is part of the precursor receptor complex and functions in the initial precursor-binding step. Hcf106 is predicted to contain a single amino terminal transmembrane domain followed by a Pro-Gly hinge, a predicted amphipathic α-helix (APH), and a loosely structured carboxy terminus. Hcf106 has been shown biochemically to insert spontaneously into thylakoid membranes. To better understand the membrane active capabilities of Hcf106, we used solid-state NMR spectroscopy to investigate those properties of the APH. In this study, synthesized peptides of the predicted Hcf106 APH (amino acids 28-65) were incorporated at increasing mol.% into 1-palmitoyl-2-oleoyl-sn-glycero-phosphocholine (POPC) and POPC/MGDG (monogalactosyldiacylglycerol; mole ratio 85:15) multilamellar vesicles (MLVs) to probe the peptide-lipid interaction. Solid-state (31)P NMR and (2)H NMR spectroscopic experiments revealed that the peptide perturbs the headgroup and the acyl chain regions of phospholipids as indicated by changes in spectral lineshape, chemical shift anisotropy (CSA) line width, and (2)H order SCD parameters. In addition, the comparison between POPC MLVs and POPC/MGDG MLVs indicated that the lipid bilayer composition affected peptide perturbation of the lipids, and such perturbation appeared to be more intense in a system more closely mimicking a thylakoid membrane.
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Affiliation(s)
- Lei Zhang
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
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9
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Zhang L, Liu L, Maltsev S, Lorigan GA, Dabney-Smith C. Solid-state NMR investigations of peptide–lipid interactions of the transmembrane domain of a plant-derived protein, Hcf106. Chem Phys Lipids 2013; 175-176:123-30. [DOI: 10.1016/j.chemphyslip.2013.09.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Revised: 09/16/2013] [Accepted: 09/17/2013] [Indexed: 02/02/2023]
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Marbella LE, Cho HS, Spence MM. Observing the translocation of a mitochondria-penetrating peptide with solid-state NMR. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1674-82. [PMID: 23567916 DOI: 10.1016/j.bbamem.2013.03.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Revised: 03/25/2013] [Accepted: 03/29/2013] [Indexed: 12/18/2022]
Abstract
A new class of penetrating peptides that can target the mitochondria with high specificity was recently discovered. In this work, we developed a model inner mitochondrial membrane, equipped with a transmembrane gradient, suitable for solid-state NMR experiments. Using solid-state NMR, we observed a mitochondria-penetrating peptide interacting with the model inner mitochondrial membrane to gain insight into the mechanism of translocation. The paramagnetic relaxation effect due to Mn(2+) ions on (13)C magic angle spinning NMR was used to measure the insertion depth of the peptide and its distribution in each monolayer of the membrane. We found that at low peptide concentration the peptide binds to the outer leaflet and at high concentration, it crosses the hydrophobic bilayer core and is distributed in both leaflets. In both concentration regimes, the peptide binds at the C2 position on the lipid acyl chain. The mitochondria-penetrating peptide crossed to the inner leaflet of the model membranes without disrupting the lamellarity. These results provide evidence that supports the electroporation model of translocation. We estimated the energy associated with crossing the inner mitochondrial membrane. We found that the transmembrane potential provides sufficient energy for the peptide to cross the hydrophobic core, which is the most unfavorable step in translocation.
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Affiliation(s)
- Lauren E Marbella
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260, USA.
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11
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Wadhwani P, Strandberg E, Heidenreich N, Bürck J, Fanghänel S, Ulrich AS. Self-assembly of flexible β-strands into immobile amyloid-like β-sheets in membranes as revealed by solid-state 19F NMR. J Am Chem Soc 2012; 134:6512-5. [PMID: 22452513 DOI: 10.1021/ja301328f] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The cationic peptide [KIGAKI](3) was designed as an amphiphilic β-strand and serves as a model for β-sheet aggregation in membranes. Here, we have characterized its molecular conformation, membrane alignment, and dynamic behavior using solid-state (19)F NMR. A detailed structure analysis of selectively (19)F-labeled peptides was carried out in oriented DMPC bilayers. It showed a concentration-dependent transition from monomeric β-strands to oligomeric β-sheets. In both states, the rigid (19)F-labeled side chains project straight into the lipid bilayer but they experience very different mobilities. At low peptide-to-lipid ratios ≤1:400, monomeric [KIGAKI](3) swims around freely on the membrane surface and undergoes considerable motional averaging, with essentially uncoupled φ/ψ torsion angles. The flexibility of the peptide backbone in this 2D plane is reminiscent of intrinsically unstructured proteins in 3D. At high concentrations, [KIGAKI](3) self-assembles into immobilized β-sheets, which are untwisted and lie flat on the membrane surface as amyloid-like fibrils. This is the first time the transition of monomeric β-strands into oligomeric β-sheets has been characterized by solid-state NMR in lipid bilayers. It promises to be a valuable approach for studying membrane-induced amyloid formation of many other, clinically relevant peptide systems.
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Affiliation(s)
- Parvesh Wadhwani
- Karlsruhe Institute of Technology (KIT), Institute of Biological Interfaces (IBG-2), POB 3640, D-76021 Karlsruhe, Germany
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Warschawski DE, Arnold AA, Beaugrand M, Gravel A, Chartrand É, Marcotte I. Choosing membrane mimetics for NMR structural studies of transmembrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1957-74. [DOI: 10.1016/j.bbamem.2011.03.016] [Citation(s) in RCA: 239] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Revised: 03/28/2011] [Accepted: 03/29/2011] [Indexed: 12/11/2022]
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13
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Cheng JTJ, Hale JD, Elliott M, Hancock REW, Straus SK. The importance of bacterial membrane composition in the structure and function of aurein 2.2 and selected variants. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:622-33. [PMID: 21144817 DOI: 10.1016/j.bbamem.2010.11.025] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 10/08/2010] [Accepted: 11/20/2010] [Indexed: 11/29/2022]
Abstract
For cationic antimicrobial peptides to become useful therapeutic agents, it is important to understand their mechanism of action. To obtain high resolution data, this involves studying the structure and membrane interaction of these peptides in tractable model bacterial membranes rather than directly utilizing more complex bacterial surfaces. A number of lipid mixtures have been used as bacterial mimetics, including a range of lipid headgroups, and different ratios of neutral to negatively charged headgroups. Here we examine how the structure and membrane interaction of aurein 2.2 and some of its variants depend on the choice of lipids, and how these models correlate with activity data in intact bacteria (MICs, membrane depolarization). Specifically, we investigated the structure and membrane interaction of aurein 2.2 and aurein 2.3 in 1:1 cardiolipin/1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (CL/POPG) (mol/mol), as an alternative to 1:1 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine(POPC)/POPG and a potential model for Gram positive bacteria such as S. aureus. The structure and membrane interaction of aurein 2.2, aurein 2.3, and five variants of aurein 2.2 were also investigated in 1:1 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE)/POPG (mol/mol) lipids as a possible model for other Gram positive bacteria, such as Bacillus cereus. Solution circular dichroism (CD) results demonstrated that the aurein peptides adopted α-helical structure in all lipid membranes examined, but demonstrated a greater helical content in the presence of POPE/POPG membranes. Oriented CD and ³¹P NMR results showed that the aurein peptides had similar membrane insertion profiles and headgroup disordering effects on POPC/POPG and CL/POPG bilayers, but demonstrated reduced membrane insertion and decreased headgroup disordering on mixing with POPE/POPG bilayers at low peptide concentrations. Since the aurein peptides behaved very differently in POPE/POPG membrane, minimal inhibitory concentrations (MICs) of the aurein peptides in B. cereus strain C737 were determined. The MIC results indicated that all aurein peptides are significantly less active against B. cereus than against S. aureus and S. epidermidis. Overall, the data suggest that it is important to use a relevant model for bacterial membranes to gain insight into the mode of action of a given antimicrobial peptide in specific bacteria.
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Affiliation(s)
- John T J Cheng
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC V6T1Z1, Canada
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14
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Verardi R, Traaseth NJ, Shi L, Porcelli F, Monfregola L, De Luca S, Amodeo P, Veglia G, Scaloni A. Probing membrane topology of the antimicrobial peptide distinctin by solid-state NMR spectroscopy in zwitterionic and charged lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:34-40. [PMID: 20719234 DOI: 10.1016/j.bbamem.2010.08.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 07/26/2010] [Accepted: 08/09/2010] [Indexed: 11/26/2022]
Abstract
Distinctin is a 47-residue antimicrobial peptide, which interacts with negatively charged membranes and is active against Gram-positive and Gram-negative bacteria. Its primary sequence comprises two linear chains of 22 (chain 1) and 25 (chain 2) residues, linked by a disulfide bridge between Cys19 of chain 1 and Cys23 of chain 2. Unlike other antimicrobial peptides, distinctin in the absence of the lipid membrane has a well-defined three-dimensional structure, which protects it from protease degradation. Here, we used static solid-state NMR spectroscopy in mechanically aligned lipid bilayers (charged or zwitterionic) to study the topology of distinctin in lipid bilayers. We found that this heterodimeric peptide adopts an ordered conformation absorbed on the surface of the membrane, with the long helix (chain 2), approximately parallel to the lipid bilayer (~5° from the membrane plane) and the short helix (chain 1) forming a ~24° angle with respect to the bilayer plane. Since the peptide does not disrupt the macroscopic alignment of charged or zwitterionic lipid bilayers at lipid-to-protein molar ratio of 50:1, it is possible that higher peptide concentrations might be needed for pore formation, or alternatively, distinctin elicits its cell disruption action by another mechanism.
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Affiliation(s)
- Raffaello Verardi
- Departments of Chemistry and Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
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15
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Bourbigot S, Fardy L, Waring AJ, Yeaman MR, Booth V. Structure of chemokine-derived antimicrobial Peptide interleukin-8alpha and interaction with detergent micelles and oriented lipid bilayers. Biochemistry 2009; 48:10509-21. [PMID: 19813761 DOI: 10.1021/bi901311p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Interleukin-8alpha (IL-8alpha) is an antimicrobial peptide derived from the chemokine IL-8. Solution NMR was used to determine the atomic-resolution structure of IL-8alpha in SDS micelles. Solid-state NMR and tryptophan fluorescence were used to probe the interaction of IL-8alpha with model membranes. The peptide interacted differently with anionic versus purely zwitterionic micelles or bilayers. Tryptophan fluorescence demonstrated a deeper position of Trp4 in SDS micelles and POPC/POPG bilayers compared to pure POPC bilayers, consistent with (2)H order parameters, which also indicated a deeper position of the peptide in POPC/POPG bilayers compared to POPC bilayers. Paramagnetic probe data showed that IL-8alpha was situated roughly parallel to the SDS micelle surface, with a slight tilt that positioned the N-terminus more deeply in the micelle compared to the C-terminus. (15)N solid-state NMR spectra indicated a similar, nearly parallel position for the peptide in POPC/POPG bilayers. (31)P and (2)H solid-state NMR demonstrated that the peptide did not induce the formation of any nonlamellar phases and did not significantly disrupt bilayer orientation in aligned model membranes composed of POPC or POPC and POPG.
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Affiliation(s)
- Sarah Bourbigot
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X9, Canada
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Sherman PJ, Jackway RJ, Gehman JD, Praporski S, McCubbin GA, Mechler A, Martin LL, Separovic F, Bowie JH. Solution Structure and Membrane Interactions of the Antimicrobial Peptide Fallaxidin 4.1a: An NMR and QCM Study. Biochemistry 2009; 48:11892-901. [DOI: 10.1021/bi901668y] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Patrick J. Sherman
- Department of Chemistry, The University of Adelaide, South Australia 5005, Australia
| | - Rebecca J. Jackway
- Department of Chemistry, The University of Adelaide, South Australia 5005, Australia
| | - John D. Gehman
- School of Chemistry, Bio21 Institute, University of Melbourne, Victoria 3010, Australia
| | | | | | - Adam Mechler
- School of Chemistry, Monash University, Victoria 3800, Australia
| | | | - Frances Separovic
- School of Chemistry, Bio21 Institute, University of Melbourne, Victoria 3010, Australia
| | - John H. Bowie
- Department of Chemistry, The University of Adelaide, South Australia 5005, Australia
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17
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Ausili A, de Godos A, Torrecillas A, Corbalán-García S, Gómez-Fernández JC. The interaction of the Bax C-terminal domain with membranes is influenced by the presence of negatively charged phospholipids. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1924-32. [DOI: 10.1016/j.bbamem.2009.06.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2009] [Revised: 06/02/2009] [Accepted: 06/08/2009] [Indexed: 11/17/2022]
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18
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Cheng JTJ, Hale JD, Elliot M, Hancock REW, Straus SK. Effect of membrane composition on antimicrobial peptides aurein 2.2 and 2.3 from Australian southern bell frogs. Biophys J 2009; 96:552-65. [PMID: 19167304 DOI: 10.1016/j.bpj.2008.10.012] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2008] [Accepted: 10/09/2008] [Indexed: 12/25/2022] Open
Abstract
The effects of hydrophobic thickness and the molar phosphatidylglycerol (PG) content of lipid bilayers on the structure and membrane interaction of three cationic antimicrobial peptides were examined: aurein 2.2, aurein 2.3 (almost identical to aurein 2.2, except for a point mutation at residue 13), and a carboxy C-terminal analog of aurein 2.3. Circular dichroism results indicated that all three peptides adopt an alpha-helical structure in the presence of a 3:1 molar mixture of 1,2-dimyristoyl-sn-glycero-3-phosphocholine/1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DMPC/DMPG), and 1:1 and 3:1 molar mixtures of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine/1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (POPC/POPG). Oriented circular dichroism data for three different lipid compositions showed that all three peptides were surface-adsorbed at low peptide concentrations, but were inserted into the membrane at higher peptide concentrations. The (31)P solid-state NMR data of the three peptides in the DMPC/DMPG and POPC/POPG bilayers showed that all three peptides significantly perturbed lipid headgroups, in a peptide or lipid composition-dependent manner. Differential scanning calorimetry results demonstrated that both amidated aurein peptides perturbed the overall phase structure of DMPC/DMPG bilayers, but perturbed the POPC/POPG chains less. The nature of the perturbation of DMPC/DMPG bilayers was most likely micellization, and for the POPC/POPG bilayers, distorted toroidal pores or localized membrane aggregate formation. Calcein release assay results showed that aurein peptide-induced membrane leakage was more severe in DMPC/DMPG liposomes than in POPC/POPG liposomes, and that aurein 2.2 induced higher calcein release than aurein 2.3 and aurein 2.3-COOH from 1:1 and 3:1 POPC/POPG liposomes. Finally, DiSC(3)5 assay data further delineated aurein 2.2 from the others by showing that it perturbed the lipid membranes of intact S. aureus C622 most efficiently, whereas aurein 2.3 had the same efficiency as gramicidin S, and aurein 2.3-COOH was the least efficient. Taken together, these data show that the membrane interactions of aurein peptides are affected by the hydrophobic thickness of the lipid bilayers and the PG content.
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Affiliation(s)
- John T J Cheng
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
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Ramamoorthy A, Lee DK, Santos JS, Henzler-Wildman KA. Nitrogen-14 Solid-State NMR Spectroscopy of Aligned Phospholipid Bilayers to Probe Peptide−Lipid Interaction and Oligomerization of Membrane Associated Peptides. J Am Chem Soc 2008; 130:11023-9. [DOI: 10.1021/ja802210u] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ayyalusamy Ramamoorthy
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055
| | - Dong-Kuk Lee
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055
| | - Jose S. Santos
- Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055
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Garner J, Inglis SR, Hook J, Separovic F, Harding MM. A solid-state NMR study of the interaction of fish antifreeze proteins with phospholipid membranes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2008; 37:1031-8. [DOI: 10.1007/s00249-008-0339-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Revised: 04/17/2008] [Accepted: 04/18/2008] [Indexed: 11/25/2022]
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21
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Abu-Baker S, Qi X, Lorigan GA. Investigating the interaction of saposin C with POPS and POPC phospholipids: a solid-state NMR spectroscopic study. Biophys J 2007; 93:3480-90. [PMID: 17704143 PMCID: PMC2072076 DOI: 10.1529/biophysj.107.107789] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The interaction of Saposin C (Sap C) with negatively charged phospholipids such as phosphatidylserine (PS) is essential for its biological function. In this study, Sap C (initially protonated in a weak acid) was inserted into multilamellar vesicles (MLVs) consisting of either 1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-L-serine] (negatively charged, POPS) or 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (neutrally charged, POPC). The MLVs were then investigated using solid-state NMR spectroscopy under neutral pH (7.0) conditions. The (2)H and (31)P solid-state NMR spectroscopic data of Sap C-POPS and Sap C-POPC MLVs (prepared under the same conditions) were compared using the (2)H order parameter profiles of the POPC-d(31) or POPS-d(31) acyl chains as well as the (31)P chemical shift anisotropy width and (31)P T(1) relaxation times of the phospholipids headgroups. All those solid-state NMR spectroscopic approaches indicate that protonated Sap C disturbs the POPS bilayers and not the POPC lipid bilayers. These observations suggest for the first time that protonated Sap C inserts into PS bilayers and forms a stable complex with the lipids even after resuspension under neutral buffer conditions. Additionally, (31)P solid-state NMR spectroscopic studies of mechanically oriented phospholipids on glass plates were conducted and perturbation effect of Sap C on both POPS and POPC bilayers was compared. Unlike POPC bilayers, the data indicates that protonated Sap C (initially protonated in a weak acid) was unable to produce well-oriented POPS bilayers on glass plates at neutral pH. Conversely, unprotonated Sap C (initially dissolved in a neutral buffer) did not interact significantly with POPS phospholipids allowing them to produce well-oriented bilayers at neutral pH.
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Affiliation(s)
- Shadi Abu-Baker
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio, USA
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22
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Kandasamy SK, Larson RG. Binding modes of protegrin-1, a beta-strand antimicrobial peptide, in lipid bilayers. MOLECULAR SIMULATION 2007. [DOI: 10.1080/08927020701313737] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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23
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Gabriel GJ, Som A, Madkour AE, Eren T, Tew GN. Infectious Disease: Connecting Innate Immunity to Biocidal Polymers. MATERIALS SCIENCE & ENGINEERING. R, REPORTS : A REVIEW JOURNAL 2007; 57:28-64. [PMID: 18160969 PMCID: PMC2153456 DOI: 10.1016/j.mser.2007.03.002] [Citation(s) in RCA: 196] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Infectious disease is a critically important global healthcare issue. In the U.S. alone there are 2 million new cases of hospital-acquired infections annually leading to 90,000 deaths and 5 billion dollars of added healthcare costs. Couple these numbers with the appearance of new antibiotic resistant bacterial strains and the increasing occurrences of community-type outbreaks, and clearly this is an important problem. Our review attempts to bridge the research areas of natural host defense peptides (HDPs), a component of the innate immune system, and biocidal cationic polymers. Recently discovered peptidomimetics and other synthetic mimics of HDPs, that can be short oligomers as well as polymeric macromolecules, provide a unique link between these two areas. An emerging class of these mimics are the facially amphiphilic polymers that aim to emulate the physicochemical properties of HDPs but take advantage of the synthetic ease of polymers. These mimics have been designed with antimicrobial activity and, importantly, selectivity that rivals natural HDPs. In addition to providing some perspective on HDPs, selective mimics, and biocidal polymers, focus is given to the arsenal of biophysical techniques available to study their mode of action and interactions with phospholipid membranes. The issue of lipid type is highlighted and the important role of negative curvature lipids is illustrated. Finally, materials applications (for instance, in the development of permanently antibacterial surfaces) are discussed as this is an important part of controlling the spread of infectious disease.
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Affiliation(s)
- Gregory J Gabriel
- Polymer Science & Engineering Department, University of Massachusetts, 120 Governors Drive, Amherst, MA 01003
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24
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Meier M, Seelig J. Thermodynamics of the Coil ⇆ β-Sheet Transition in a Membrane Environment. J Mol Biol 2007; 369:277-89. [PMID: 17412361 DOI: 10.1016/j.jmb.2007.02.082] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2006] [Revised: 02/21/2007] [Accepted: 02/22/2007] [Indexed: 11/19/2022]
Abstract
Biologically important peptides such as the Alzheimer peptide Abeta(1-40) display a reversible random coil <==>beta-structure transition at anionic membrane surfaces. In contrast to the well-studied random coil left arrow over right arrow alpha-helix transition of amphipathic peptides, there is a dearth on information on the thermodynamic and kinetic parameters of the random coil left arrow over right arrow beta-structure transition. Here, we present a new method to quantitatively analyze the thermodynamic parameters of the membrane-induced beta-structure formation. We have used the model peptide (KIGAKI)(3) and eight analogues in which two adjacent amino acids were substituted by their d-enantiomers. The positions of the d,d pairs were shifted systematically along the three identical segments of the peptide chain. The beta-structure content of the peptides was measured in solution and when bound to anionic lipid membranes with circular dichroism spectroscopy. The thermodynamic binding parameters were determined with isothermal titration calorimetry and the binding isotherms were analysed by combining a surface partition equilibrium with the Gouy-Chapman theory. The thermodynamic parameters were found to be linearly correlated with the extent of beta-structure formation. beta-Structure formation at the membrane surface is characterized by an enthalpy change of DeltaH(beta)=-0.23 kcal/mol per residue, an entropy change of DeltaS(beta)=-0.24 cal/mol K residue and a free energy change of DeltaG(beta)=-0.15 kcal/mol residue. An increase in temperature induces an unfolding of beta-structure. The residual free energy of membrane-induced beta-structure formation is close to that of membrane-induced alpha-helix formation.
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Affiliation(s)
- Matthias Meier
- Department of Biophysical Chemistry, Biozentrum, University of Basel, Klingelbergstrasse 50/70, CH-4056 Basel, Switzerland
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25
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Veresov VG, Davidovskii AI. Monte Carlo simulations of tBid association with the mitochondrial outer membrane. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 37:19-33. [PMID: 17375293 DOI: 10.1007/s00249-007-0149-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2006] [Revised: 02/02/2007] [Accepted: 02/24/2007] [Indexed: 12/24/2022]
Abstract
Bid, a BH3-only pro-apoptopic member of the BCL-2 protein family, regulates cell death at the level of mitochondrial cytochrome c efflux. Bid consists of 8 alpha-helices (H1-H8, respectively) and is soluble cytosolic protein in its native state. Proteolysis of the N-terminus (encompassing H1 and H2) of Bid by caspase 8 in apoptosis yields activated "tBid" (truncated Bid), which translocates to the mitochondria and induces the efflux of cytochrome c. The release of cytochrome c from mitochondria to the cytosol constitutes a critical control point in apoptosis that is regulated by interaction of tBid protein with mitochondrial membrane. tBid displays structural homology to channel-forming bacterial toxins, such as colicins or transmembrane domain of diphtheria toxin. By analogy, it has been hypothesized that tBid would unfold and insert into the lipid bilayer of the mitochondria outer membrane (MOM) upon membrane association. However, it has been shown recently that unlike colicins and the transmembrane domain of diphtheria toxin, tBid binds to the lipid bilayer maintaining alpha-helical conformation of its helices without adopting a transmembrane orientation by them. Here, the mechanism of the association of tBid with the model membrane mimicking the mitochondrial membrane is studied by Monte Carlo simulations, taking into account the underlying energetics. A novel two-stage hierarchical simulation protocol combining coarse-grained discretization of conformational space with subsequent refinements was applied which was able to generate the protein conformation and its location in the membrane using modest computational resources. The simulations show that starting from NMR-established conformation in the solution, the protein associates with the membrane without adopting the transmembrane orientation. The configuration (conformation and location) of tBid providing the lowest free energy for the system protein/membrane/solvent has been obtained. The simulations reveal that tBid upon association with the membrane undergoes significant conformational changes primarily due to rotations within the loops between helices H4 and H5, H6 and H7, H7 and H8. It is established that in the membrane-bound state of tBid-monomer helices H3 and H5 have the locations exposed to the solution, helices H6 and H8 are partly buried and helices H4 and H7 are buried into the membrane at shallow depth. The average orientation of tBid bound to the membrane in the most stable configuration reported here is in satisfactory agreement with the evaluations obtained by indirect experimental means.
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Affiliation(s)
- Valery G Veresov
- Department of Cell Biophysics, Institute of Biophysics and Cell Engineering, Academicheskaya St. 27, Minsk 220072, Belarus.
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Ramamoorthy A, Kandasamy SK, Lee DK, Kidambi S, Larson RG. Structure, topology, and tilt of cell-signaling peptides containing nuclear localization sequences in membrane bilayers determined by solid-state NMR and molecular dynamics simulation studies. Biochemistry 2007; 46:965-75. [PMID: 17240980 PMCID: PMC2527728 DOI: 10.1021/bi061895g] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cell-signaling peptides have been extensively used to transport functional molecules across the plasma membrane into living cells. These peptides consist of a hydrophobic sequence and a cationic nuclear localization sequence (NLS). It has been assumed that the hydrophobic region penetrates the hydrophobic lipid bilayer and delivers the NLS inside the cell. To better understand the transport mechanism of these peptides, in this study, we investigated the structure, orientation, tilt of the peptide relative to the bilayer normal, and the membrane interaction of two cell-signaling peptides, SA and SKP. Results from CD and solid-state NMR experiments combined with molecular dynamics simulations suggest that the hydrophobic region is helical and has a transmembrane orientation with the helical axis tilted away from the bilayer normal. The influence of the hydrophobic mismatch, between the hydrophobic length of the peptide and the hydrophobic thickness of the bilayer, on the tilt angle of the peptides was investigated using thicker POPC and thinner DMPC bilayers. NMR experiments showed that the hydrophobic domain of each peptide has a tilt angle of 15 +/- 3 degrees in POPC, whereas in DMPC, 25 +/- 3 degree and 30 +/- 3 degree tilts were observed for SA and SKP peptides, respectively. These results are in good agreement with molecular dynamics simulations, which predict a tilt angle of 13.3 degrees (SA in POPC), 16.4 degrees (SKP in POPC), 22.3 degrees (SA in DMPC), and 31.7 degrees (SKP in DMPC). These results and simulations on the hydrophobic fragment of SA or SKP suggest that the tilt of helices increases with a decrease in bilayer thickness without changing the phase, order, and structure of the lipid bilayers.
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Affiliation(s)
- Ayyalusamy Ramamoorthy
- Biophysics Research Division, University of Michigan, Ann Arbor, Michigan 48109-1055, USA.
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27
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Abu-Baker S, Lorigan GA. Phospholamban and its phosphorylated form interact differently with lipid bilayers: a 31P, 2H, and 13C solid-state NMR spectroscopic study. Biochemistry 2006; 45:13312-22. [PMID: 17073452 PMCID: PMC2586141 DOI: 10.1021/bi0614028] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Phospholamban (PLB) is a 52-amino acid integral membrane protein that helps to regulate the flow of Ca(2+) ions in cardiac muscle cells. Recent structural studies on the PLB pentamer and the functionally active monomer (AFA-PLB) debate whether its cytoplasmic domain, in either the phosphorylated or dephosphorylated states, is alpha-helical in structure as well as whether it associates with the lipid head groups (Oxenoid, K. (2005) Proc. Natl. Acad. Sci. U.S.A. 102, 10870-10875; Karim, C. B. (2004) Proc. Natl. Acad. Sci. U.S.A. 101, 14437-14442; Andronesi, C.A. (2005) J. Am. Chem. Soc. 127, 12965-12974; Li, J. (2003) Biochemistry 42, 10674-10682; Metcalfe, E. E. (2005) Biochemistry 44, 4386-4396: Clayton, J. C. (2005) Biochemistry 44, 17016-17026). Comparing the secondary structure of the PLB pentamer and its phosphorylated form (P-PLB) as well as their interaction with the lipid bilayer is crucial in order to understand its regulatory function. Therefore, in this study, the full-length wild-type (WT) PLB and P-PLB were incorporated into 1-palmitoyl-2-oleoyl-sn-glycero-phosphocholine (POPC) phospholipid bilayers and studied utilizing solid-state NMR spectroscopy. The analysis of the (2)H and (31)P solid-state NMR data of PLB and P-PLB in POPC multilamellar vesicles (MLVs) indicates that a direct interaction takes place between both proteins and the phospholipid head groups. However, the interaction of P-PLB with POPC bilayers was less significant compared that with PLB. Moreover, the secondary structure using (13)C=O site-specific isotopically labeled Ala15-PLB and Ala15-P-PLB in POPC bilayers suggests that this residue, located in the cytoplasmic domain, is a part of an alpha-helical structure for both PLB and P-PLB.
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Affiliation(s)
- Shadi Abu-Baker
- Department of Chemistry and Biochemistry Miami University, Oxford, Ohio 45056
| | - Gary A. Lorigan
- Department of Chemistry and Biochemistry Miami University, Oxford, Ohio 45056
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Chen X, Chen Z. SFG studies on interactions between antimicrobial peptides and supported lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1257-73. [PMID: 16524559 DOI: 10.1016/j.bbamem.2006.01.017] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2005] [Revised: 01/11/2006] [Accepted: 01/24/2006] [Indexed: 11/29/2022]
Abstract
The mode of action of antimicrobial peptides (AMPs) in disrupting cell membrane bilayers is of fundamental importance in understanding the efficiency of different AMPs, which is crucial to design antibiotics with improved properties. Recent developments in the field of sum frequency generation (SFG) vibrational spectroscopy have made it a powerful and unique biophysical technique in investigating the interactions between AMPs and a single substrate supported planar lipid bilayer. We will review some of the recent progress in applying SFG to study membrane lipid bilayers and discuss how SFG can provide novel information such as real-time bilayer structure change and AMP orientation during AMP-lipid bilayer interactions in a very biologically relevant manner. Several examples of applying SFG to monitor such interactions between AMPs and a dipalmitoyl phosphatidylglycerol (DPPG) bilayer are presented. Different modes of actions are observed for melittin, tachyplesin I, d-magainin 2, MSI-843, and a synthetic antibacterial oligomer, demonstrating that SFG is very effective in the study of AMPs and AMP-lipid bilayer interactions.
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Affiliation(s)
- Xiaoyun Chen
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA
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Ramamoorthy A, Thennarasu S, Tan A, Gottipati K, Sreekumar S, Heyl DL, An FYP, Shelburne CE. Deletion of all cysteines in tachyplesin I abolishes hemolytic activity and retains antimicrobial activity and lipopolysaccharide selective binding. Biochemistry 2006; 45:6529-40. [PMID: 16700563 PMCID: PMC2515376 DOI: 10.1021/bi052629q] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tachyplesin I is a cyclic beta-sheet antimicrobial peptide isolated from the hemocytes of Tachypleus tridentatus. The four cysteine residues in tachyplesin I play a structural role in imparting amphipathicity to the peptide which has been shown to be essential for its activity. We investigated the role of amphipathicity using an analogue of tachyplesin I (TP-I), CDT (KWFRVYRGIYRRR-NH(2)), in which all four cysteines were deleted. Like TP-I, CDT shows antimicrobial activity and disrupts Escherichia coli outer membrane and model membranes mimicking bacterial inner membranes at micromolar concentrations. The CDT peptide does not cause hemolysis up to 200 microg/mL while TP-I showed about 10% hemolysis at 100 microg/mL and about 25% hemolysis at 150 microg/mL. Peptide-into-lipid titrations under isothermal conditions reveal that the interaction of CDT with lipid membranes is an enthalpy-driven process. Binding assays performed using fluorometry demonstrate that the peptide CDT binds and inserts into only negatively charged membranes. The peptide-induced thermotropic phase transition of MLVs formed of DMPC and the DMPC/DMPG (7:3) mixture suggests specific lipid-peptide interactions. The circular dichroism study shows that the peptide exists as an unordered structure in an aqueous buffer and adopts a more ordered beta-structure upon binding to negatively charged membrane. The NMR data suggest that CDT binding to negatively charged bilayers induces a change in the lipid headgroup conformation with the lipid headgroup moving out of the bilayer surface toward the water phase, and therefore, a barrel stave mechanism of membrane disruption is unlikely as the peptide is located near the headgroup region of lipids. The lamellar phase (31)P chemical shift spectra observed at various concentrations of the peptide in bilayers suggest that the peptide may function neither via fragmentation of bilayers nor by promoting nonlamellar structures. NMR and fluorescence data suggest that the presence of cholesterol inhibits the peptide binding to the bilayers. These properties help to explain that cysteine residues may not contribute to antimicrobial activity and that the loss of hemolytic activity is due to lack of hydrophobicity and amphipathicity.
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Affiliation(s)
- Ayyalusamy Ramamoorthy
- Department of Chemistry and Biophysics Research Division, The University of Michigan, Ann Arbor, Michigan 48109-1055, USA.
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Ramamoorthy A, Thennarasu S, Lee DK, Tan A, Maloy L. Solid-state NMR investigation of the membrane-disrupting mechanism of antimicrobial peptides MSI-78 and MSI-594 derived from magainin 2 and melittin. Biophys J 2006; 91:206-16. [PMID: 16603496 PMCID: PMC1479060 DOI: 10.1529/biophysj.105.073890] [Citation(s) in RCA: 220] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The mechanism of membrane interaction of two amphipathic antimicrobial peptides, MSI-78 and MSI-594, derived from magainin-2 and melittin, is presented. Both the peptides show excellent antimicrobial activity. The 8-anilinonaphthalene-1-sulfonic acid uptake experiment using Escherichia coli cells suggests that the outer membrane permeabilization is mainly due to electrostatic interactions. The interaction of MSI-78 and MSI-594 with lipid membranes was studied using 31P and 2H solid-state NMR, circular dichroism, and differential scanning calorimetry techniques. The binding of MSI-78 and MSI-594 to the lipid membrane is associated with a random coil to alpha-helix structural transition. MSI-78 and MSI-594 also induce the release of entrapped dye from POPC/POPG (3:1) vesicles. Measurement of the phase-transition temperature of peptide-DiPoPE dispersions shows that both MSI-78 and MSI-594 repress the lamellar-to-inverted hexagonal phase transition by inducing positive curvature strain. 15N NMR data suggest that both the peptides are oriented nearly perpendicular to the bilayer normal, which infers that the peptides most likely do not function via a barrel-stave mechanism of membrane-disruption. Data obtained from 31P NMR measurements using peptide-incorporated POPC and POPG oriented lamellar bilayers show a disorder in the orientation of lipids up to a peptide/lipid ratio of 1:20, and the formation of nonbilayer structures at peptide/lipid ratio>1:8. 2H-NMR experiments with selectively deuterated lipids reveal peptide-induced disorder in the methylene units of the lipid acyl chains. These results are discussed in light of lipid-peptide interactions leading to the disruption of membrane via either a carpet or a toroidal-type mechanism.
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Affiliation(s)
- Ayyalusamy Ramamoorthy
- Biophysics Research Division and Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, USA.
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Ramamoorthy A, Thennarasu S, Tan A, Lee DK, Clayberger C, Krensky AM. Cell selectivity correlates with membrane-specific interactions: a case study on the antimicrobial peptide G15 derived from granulysin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:154-63. [PMID: 16579960 DOI: 10.1016/j.bbamem.2006.02.014] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2005] [Revised: 02/08/2006] [Accepted: 02/13/2006] [Indexed: 11/18/2022]
Abstract
A 15-residue peptide dimer G15 derived from the cell lytic protein granulysin has been shown to exert potent activity against microbes, including E. coli, but not against human Jurkat cells [Z. Wang, E. Choice, A. Kaspar, D. Hanson, S. Okada, S.C. Lyu, A.M. Krensky, C. Clayberger, Bactericidal and tumoricidal activities of synthetic peptides derived from granulysin. J. Immunol. 165 (2000) 1486-1490]. We investigated the target membrane selectivity of G15 using fluorescence, circular dichroism and 31P NMR methods. The ANS uptake assay shows that the extent of E. coli outer membrane disruption depends on G15 concentration. 31P NMR spectra obtained from E. coli total lipid bilayers incorporated with G15 show disruption of lipid bilayers. Fluorescence binding studies on the interaction of G15 with synthetic liposomes formed of E. coli lipids suggest a tight binding of the peptide at the membrane interface. The peptide also binds to negatively charged POPC/POPG (3:1) lipid vesicles but fails to insert deep into the membrane interior. These results are supported by the peptide-induced changes in the measured isotropic chemical shift and T1 values of POPG in 3:1 POPC:POPG multilamellar vesicles while neither a non-lamellar phase nor a fragmentation of bilayers was observed from NMR studies. The circular dichroism studies reveal that the peptide exists as a random coil in solution but folds into a less ordered conformation upon binding to POPC/POPG (3:1) vesicles. However, G15 does not bind to lipid vesicles made of POPC/POPG/Chl (9:1:1) mixture, mimicking tumor cell membrane. These results explain the susceptibility of E. coli and the resistance of human Jurkat cells to G15, and may have implications in designing membrane-selective therapeutic agents.
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Affiliation(s)
- Ayyalusamy Ramamoorthy
- Department of Chemistry and Biophysics Research Division, University of Michigan, 930 N. University Avenue, Ann Arbor, MI 48109-1055, USA.
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Lu JX, Blazyk J, Lorigan GA. Exploring membrane selectivity of the antimicrobial peptide KIGAKI using solid-state NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1303-13. [PMID: 16537078 DOI: 10.1016/j.bbamem.2006.02.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2005] [Revised: 02/01/2006] [Accepted: 02/02/2006] [Indexed: 11/25/2022]
Abstract
The designed antimicrobial peptide KIGAKIKIGAKIKIGAKI possesses enhanced membrane selectivity for bacterial lipids, such as phosphatidylethanolamine and phosphatidylglycerol. The perturbation of the bilayer by the peptide was first monitored using oriented bilayer samples on glass plates. The alignment of POPE/POPG model membranes with respect to the bilayer normal was severely altered at 4 mol% KIGAKI while the alignment of POPC bilayers was retained. The interaction mechanism between the peptide and POPE/POPG bilayers was investigated by carefully comparing three bilayer MLV samples (POPE bilayers, POPG bilayers, and POPE/POPG 4/1 bilayers). KIGAKI induces the formation of an isotropic phase for POPE/POPG bilayers, but only a slight change in the (31)P NMR CSA line shape for both POPE and POPG bilayers, indicating the synergistic roles of POPE and POPG lipids in the disruption of the membrane structure by KIGAKI. (2)H NMR powder spectra show no reduction of the lipid chain order for both POPG and POPE/POPG bilayers upon peptide incorporation, supporting the evidence that the peptide acts as a surface peptide. (31)P longitudinal relaxation studies confirmed that different dynamic changes occurred upon interaction of the peptide with the three different lipid bilayers, indicating that the strong electrostatic interaction between the cationic peptide KIGAKI and anionic POPG lipids is not the only factor in determining the antimicrobial activity. Furthermore, (31)P and (2)H NMR powder spectra demonstrated a change in membrane characteristics upon mixing of POPE and POPG lipids. The interaction between different lipids, such as POPE and POPG, in the mixed bilayers may provide the molecular basis for the KIGAKI carpet mechanism in the permeation of the membrane.
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Affiliation(s)
- Jun-xia Lu
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
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Moon JY, Henzler-Wildman KA, Ramamoorthy A. Expression and purification of a recombinant LL-37 from Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2006; 1758:1351-8. [PMID: 16542635 DOI: 10.1016/j.bbamem.2006.02.003] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2005] [Revised: 02/02/2006] [Accepted: 02/07/2006] [Indexed: 11/17/2022]
Abstract
Human cathelicidin-derived LL-37 is a 37-residue cationic, amphipathic alpha-helical peptide. It is an active component of mammalian innate immunity. LL-37 has several biological functions including a broad spectrum of antimicrobial activities and LPS-neutralizing activity. In order to determine the high-resolution three-dimensional structure of LL-37 using NMR spectroscopy, it is important to obtain the peptide with isotopic labels such as (15)N, (13)C and/or (2)H. Since it is less expensive to obtain such a peptide biologically, in this study, we report for the first time a method to express in E. coli and purify LL-37 using Glutathione S-transferase (GST) fusion system. LL-37 gene was inserted into vector pGEX-4T3 and expressed as a GST-LL-37 fusion protein in BL21(DE3) strain. The recombinant GST-LL-37 protein was purified with a yield of 8 mg/l by affinity chromatography and analyzed its biochemical and spectroscopic properties. Factor Xa was used to cleave a 4.5-kDa LL-37 from the GST-LL-37 fusion protein and the peptide was purified using a reverse-phase HPLC on a Vydac C(18) column with a final yield of 0.3 mg/l. The protein purified using reverse-phase HPLC was confirmed to be LL-37 by the analyses of Western blot and MALDI-TOF-Mass spectrometry. E. coli cells harboring the expression vector pGEX-4T3-LL-37 were grown in the presence of the (15)N-labeled M9 minimal medium and culture conditions were optimized to obtain uniform (15)N enrichment in the constitutively expressed LL-37 peptide. These results suggest that our production method will be useful in obtaining a large quantity of recombinant LL-37 peptide for NMR studies.
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Affiliation(s)
- Ja-Young Moon
- Department of Chemistry and Biophysics Research Division, University of Michigan, Ann Arbor, MI 48109-1055, USA
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Lu JX, Damodaran K, Lorigan GA. Probing membrane topology by high-resolution 1H-13C heteronuclear dipolar solid-state NMR spectroscopy. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2006; 178:283-7. [PMID: 16275029 DOI: 10.1016/j.jmr.2005.09.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Revised: 09/15/2005] [Accepted: 09/21/2005] [Indexed: 05/05/2023]
Abstract
Membrane topology changes introduced by the association of biologically pertinent molecules with membranes were analyzed utilizing the (1)H-(13)C heteronuclear dipolar solid-state NMR spectroscopy technique (SAMMY) on magnetically aligned phospholipid bilayers (bicelles). The phospholipids (1)H-(13)C dipolar coupling profiles lipid motions at the headgroup, glycerol backbone, and the acyl chain region. The transmembrane segment of phospholamban, the antimicrobial peptide (KIGAKI)(3) and cholesterol were incorporated into the bicelles, respectively. The lipids (1)H-(13)C dipolar coupling profiles exhibit different shifts in the dipolar coupling contour positions upon the addition of these molecules, demonstrating a variety of interaction mechanisms exist between the biological molecules and the membranes. The membrane topology changes revealed by the SAMMY pulse sequence provide a complete screening method for analyzing how these biologically active molecules interact with the membrane.
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Affiliation(s)
- Jun-Xia Lu
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
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