1
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Roy S, Kumari M, Haloi P, Chawla S, Konkimalla VB, Kumar A, Kashyap HK, Jaiswal A. Quaternary ammonium substituted pullulan accelerates wound healing and disinfects Staphylococcus aureus infected wounds in mouse through an atypical 'non-pore forming' pathway of bacterial membrane disruption. Biomater Sci 2021; 10:581-601. [PMID: 34907410 DOI: 10.1039/d1bm01542g] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The emergence of multi-drug resistant pathogens has fueled the search for alternatives to the existing line of antibiotics that can eradicate pathogens without inducing resistance development. Here, we report the accelerated wound healing and disinfection potential of a non-amphiphilic quaternized fungal exopolysaccharide, pullulan, without resistance generation in pathogens. The quaternary ammonium substituted pullulan (CP) derivatives showed excellent bactericidal activity against both Gram negative (MBC90 = 1.5 μg mL-1) and Gram positive (MBC90 = 0.25 μg mL-1) bacteria at very low concentrations without showing any toxicity towards mammalian cells. A combined approach of atomistic molecular dynamics simulation and experimental assays revealed that CP exerts a membrane directed bactericidal action through an atypical "non-pore forming" pathway which is not yet established for any known antibacterial polysaccharides. This involves an increase in membrane roughness, disorder among anionic lipid tails, formation of localized anionic lipid clusters and membrane depolarization, finally leading to physical disruption of the membrane integrity. Moreover, CP also displayed biofilm eradication abilities and emerged as an excellent therapeutic material for disinfection and healing of infected wounds. The present work shows the potential of exploiting polysaccharides as next-generation broad-spectrum antimicrobials and provides a platform for further development of rationally designed pullulan-based functional materials for biomedical applications.
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Affiliation(s)
- Shounak Roy
- School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Mandi, Himachal Pradesh 175005, India.
| | - Monika Kumari
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
| | - Prakash Haloi
- School of Biological Sciences, National Institute of Science Education and Research, HBNI, Jatni, Odisha 752050, India
| | - Saurabh Chawla
- School of Biological Sciences, National Institute of Science Education and Research, HBNI, Jatni, Odisha 752050, India
| | - V Badireenath Konkimalla
- School of Biological Sciences, National Institute of Science Education and Research, HBNI, Jatni, Odisha 752050, India
| | - Ajith Kumar
- School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Mandi, Himachal Pradesh 175005, India.
| | - Hemant K Kashyap
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
| | - Amit Jaiswal
- School of Basic Sciences, Indian Institute of Technology Mandi, Kamand, Mandi, Himachal Pradesh 175005, India.
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2
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Vishweshwaraiah YL, Acharya A, Hegde V, Prakash B. Rational design of hyperstable antibacterial peptides for food preservation. NPJ Sci Food 2021; 5:26. [PMID: 34471114 PMCID: PMC8410836 DOI: 10.1038/s41538-021-00109-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2021] [Accepted: 06/11/2021] [Indexed: 02/07/2023] Open
Abstract
We describe the design of peptides with properties like thermostability, pH stability, and antibacterial activity against a few bacterial food pathogens. Insights obtained from classical structure-function analysis of natural peptides and their mutants through antimicrobial and enzymatic assays are used to rationally develop a set of peptides. pH and thermostability assays were performed to demonstrate robust antimicrobial activity post-treatment with high temperatures and at wide pH ranges. We have also investigated the mode of action of these hyperstable peptides using membrane permeability assays, electron microscopy, and molecular dynamics simulations. Notably, through mutational studies, we show that these peptides elicit their antibacterial action via both membrane destabilization and inhibition of intracellular trypsin-the two functions attributable to separate peptide segments. Finally, toxicity studies and food preservation assays demonstrate the safety and efficacy of the designed peptides for food preservation. Overall, the study provides a general 'blueprint' for the development of stable antimicrobial peptides (AMPs). Insights obtained from this work may also be combined with combinatorial methods in high-throughput studies for future development of antimicrobials for various applications.
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Affiliation(s)
- Yashavantha L. Vishweshwaraiah
- grid.417629.f0000 0004 0501 5711Department of Molecular Nutrition, CSIR-Central Food Technological Research Institute, Mysore, India
| | - Abhishek Acharya
- grid.417629.f0000 0004 0501 5711Department of Molecular Nutrition, CSIR-Central Food Technological Research Institute, Mysore, India
| | - Vinayak Hegde
- grid.417629.f0000 0004 0501 5711Department of Molecular Nutrition, CSIR-Central Food Technological Research Institute, Mysore, India ,grid.469887.c0000 0004 7744 2771Academy of Scientific and Innovative Research, Ghaziabad, Uttar Pradesh India
| | - Balaji Prakash
- grid.417629.f0000 0004 0501 5711Department of Molecular Nutrition, CSIR-Central Food Technological Research Institute, Mysore, India ,grid.448607.90000 0004 1781 3606Division of Biological and Life Sciences, School of Arts and Sciences, Ahmedabad University, Ahmedabad, Gujarat India
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3
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Talandashti R, Mehrnejad F, Rostamipour K, Doustdar F, Lavasanifar A. Molecular Insights into Pore Formation Mechanism, Membrane Perturbation, and Water Permeation by the Antimicrobial Peptide Pleurocidin: A Combined All-Atom and Coarse-Grained Molecular Dynamics Simulation Study. J Phys Chem B 2021; 125:7163-7176. [PMID: 34171196 DOI: 10.1021/acs.jpcb.1c01954] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The antimicrobial peptide (AMP) pleurocidin has a broad antimicrobial activity against Gram-negative and Gram-positive bacteria by perturbation and permeabilizing their membranes; however, understanding the mechanism of action of pleurocidin, a promising AMP for replacing current antibiotic agents, has tremendous importance for future applications. Hence, we applied all-atom (AA) and coarse-grained (CG) molecular dynamics (MD) simulations to provide molecular-level insights into the pore-forming process. The early stages of pore formation were examined by 500 ns AA simulations. The results demonstrated that pleurocidin has the ability to create a pore with two peptides through which water molecules can flow. However, the results of the 25 μs CG simulations indicate that the final pore will be created by accumulation of more than two peptides. The results show that after 2.5 μs of simulations, peptides will aggregate and create a channel-like pore across the membrane. Pleurocidin can construct a more efficient and stable pore in the anionic membranes than in the zwitterionic membranes. Moreover, the structure amphipathicity, polarity, and basic residues play crucial roles in the pore formation and flow of water molecules across the lipid bilayers. In general, the findings revealed that based on the lipid compositions of the membranes, pleurocidin could act by forming either toroidal or disordered toroidal pores with different peptide arrangements.
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Affiliation(s)
- Reza Talandashti
- Infectious Diseases and Tropical Medicine Research Center, Shahid Beheshti University of Medical Sciences, P. O. Box: 1985717443 Tehran, Iran.,Department of Life Sciences Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran 14395-1561, Iran
| | - Faramarz Mehrnejad
- Department of Life Sciences Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran 14395-1561, Iran
| | - Kiana Rostamipour
- Department of Life Sciences Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran 14395-1561, Iran
| | - Farahnoosh Doustdar
- Department of Life Sciences Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran 14395-1561, Iran.,Department of Microbiology, Faculty of Medicine, Shahid Beheshti University of Medical Sciences, Tehran 19839-63113, Iran
| | - Afsaneh Lavasanifar
- Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Alberta T6G 2E1, Canada
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4
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Simcock PW, Bublitz M, Cipcigan F, Ryadnov MG, Crain J, Stansfeld PJ, Sansom MSP. Membrane Binding of Antimicrobial Peptides Is Modulated by Lipid Charge Modification. J Chem Theory Comput 2021; 17:1218-1228. [PMID: 33395285 DOI: 10.1021/acs.jctc.0c01025] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptide interactions with lipid bilayers play a key role in a range of biological processes and depend on electrostatic interactions between charged amino acids and lipid headgroups. Antimicrobial peptides (AMPs) initiate the killing of bacteria by binding to and destabilizing their membranes. The multiple peptide resistance factor (MprF) provides a defense mechanism for bacteria against a broad range of AMPs. MprF reduces the negative charge of bacterial membranes through enzymatic conversion of the anionic lipid phosphatidyl glycerol (PG) to either zwitterionic alanyl-phosphatidyl glycerol (Ala-PG) or cationic lysyl-phosphatidyl glycerol (Lys-PG). The resulting change in the membrane charge is suggested to reduce the binding of AMPs to membranes, thus impeding downstream AMP activity. Using coarse-grained molecular dynamics to investigate the effects of these modified lipids on AMP binding to model membranes, we show that AMPs have substantially reduced affinity for model membranes containing Ala-PG or Lys-PG. More than 5000 simulations in total are used to define the relationship between lipid bilayer composition, peptide sequence (using five different membrane-active peptides), and peptide binding to membranes. The degree of interaction of a peptide with a membrane correlates with the membrane surface charge density. Free energy profile (potential of mean force) calculations reveal that the lipid modifications due to MprF alter the energy barrier to peptide helix penetration of the bilayer. These results will offer a guide to the design of novel peptides, which addresses the issue of resistance via MprF-mediated membrane modification.
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Affiliation(s)
- Patrick W Simcock
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
| | - Maike Bublitz
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
| | | | - Maxim G Ryadnov
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, U.K
| | - Jason Crain
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
- IBM Research UK, Hartree Centre, Daresbury WA4 4AD, U.K
| | - Phillip J Stansfeld
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
- School of Life Sciences and Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
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5
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Rončević T, Puizina J, Tossi A. Antimicrobial Peptides as Anti-Infective Agents in Pre-Post-Antibiotic Era? Int J Mol Sci 2019; 20:E5713. [PMID: 31739573 PMCID: PMC6887943 DOI: 10.3390/ijms20225713] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 11/08/2019] [Accepted: 11/11/2019] [Indexed: 02/06/2023] Open
Abstract
Resistance to antibiotics is one of the main current threats to human health and every year multi-drug resistant bacteria are infecting millions of people worldwide, with many dying as a result. Ever since their discovery, some 40 years ago, the antimicrobial peptides (AMPs) of innate defense have been hailed as a potential alternative to conventional antibiotics due to their relatively low potential to elicit resistance. Despite continued effort by both academia and start-ups, currently there are still no antibiotics based on AMPs in use. In this study, we discuss what we know and what we do not know about these agents, and what we need to know to successfully translate discovery to application. Understanding the complex mechanics of action of these peptides is the main prerequisite for identifying and/or designing or redesigning novel molecules with potent biological activity. However, other aspects also need to be well elucidated, i.e., the (bio)synthetic processes, physiological and pathological contexts of their activity, and a quantitative understanding of how physico-chemical properties affect activity. Research groups worldwide are using biological, biophysical, and algorithmic techniques to develop models aimed at designing molecules with the necessary blend of antimicrobial potency and low toxicity. Shedding light on some open questions may contribute toward improving this process.
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Affiliation(s)
- Tomislav Rončević
- Department of Biology, Faculty of Science, University of Split, 21000 Split, Croatia;
- Laboratory for Aquaculture, Institute of Oceanography and Fisheries, 21000 Split, Croatia
| | - Jasna Puizina
- Department of Biology, Faculty of Science, University of Split, 21000 Split, Croatia;
| | - Alessandro Tossi
- Department of Life Sciences, University of Trieste, 34127 Trieste, Italy;
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6
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Song C, de Groot BL, Sansom MSP. Lipid Bilayer Composition Influences the Activity of the Antimicrobial Peptide Dermcidin Channel. Biophys J 2019; 116:1658-1666. [PMID: 31010668 DOI: 10.1016/j.bpj.2019.03.033] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 03/23/2019] [Accepted: 03/28/2019] [Indexed: 10/27/2022] Open
Abstract
Antimicrobial peptides (AMPs) carry great potential as new antibiotics against "superbugs." Dermcidin (DCD), a broad-spectrum AMP in human sweat, has been recently crystallized in its oligomeric state and showed channel-like properties. In this work, we performed multiscale molecular dynamics simulations to study how the membrane composition influences the behavior of a transmembrane pore formed by the DCD oligomer in the hope of revealing the origin of the membrane selectivity of this AMP toward bacteria. Our results indicate that bilayers composed of various lipids (DMPC, DPPC, and DSPC) with different thicknesses result in different orientations of the DCD oligomer when embedded in lipid bilayers. The thicker the bilayer, the less tilted the channel. Cholesterol makes the bilayers more rigid and thicker, which also affects the orientation of the channel. Furthermore, we observed that the predicted conductance of the channel from computational electrophysiology simulations is related to its orientation in the lipid bilayer: the larger the tilt, the larger the conductance. Our results indicate that the membrane composition has a significant influence on the activity of the DCD channel, with thicker, cholesterol-rich membranes showing lower conductance than that of thinner membranes.
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Affiliation(s)
- Chen Song
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China; Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China; Department of Biochemistry, University of Oxford, Oxford, United Kingdom.
| | - Bert L de Groot
- Department of Theoretical and Computational Biophysics, Max-Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
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7
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Simulation-Guided Rational de Novo Design of a Small Pore-Forming Antimicrobial Peptide. J Am Chem Soc 2019; 141:4839-4848. [PMID: 30839209 DOI: 10.1021/jacs.8b11939] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In the age of failing small-molecule antibiotics, tapping the near-infinite structural and chemical repertoire of antimicrobial peptides (AMPs) offers one of the most promising routes toward developing next-generation antibacterial compounds. One of the key impediments en route is the lack of methodologies for systematic rational design and optimization of new AMPs. Here we present a new simulation-guided rational design approach and apply it to develop a potent new AMP. We show that unbiased atomic detail molecular dynamics (MD) simulations are able to predict structures formed by evolving peptide designs enabling structure-based rational fine-tuning of functional properties. Starting from a 14-residue poly leucine template we demonstrate the design of a minimalistic potent new AMP. Consisting of only four types of amino acids (LDKA), this peptide forms large pores in microbial membranes at very low peptide-to-lipid ratios (1:1000) and exhibits low micromolar activity against common Gram-positive and Gram-negative pathogenic bacteria. Remarkably, the four amino acids were sufficient to encode preferential poration of bacterial membranes with negligible damage to red blood cells at bactericidal concentrations. As the sequence is too short to span cellular membranes, pores are formed by stacking of channels in each bilayer leaflet.
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8
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Ermakova E, Kurbanov R, Zuev Y. Coarse-grained molecular dynamics of membrane semitoroidal pore formation in model lipid-peptide systems. J Mol Graph Model 2019; 87:1-10. [DOI: 10.1016/j.jmgm.2018.11.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 11/06/2018] [Accepted: 11/06/2018] [Indexed: 12/31/2022]
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9
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Jiang Z, Zhang H. Curvature effect and stabilize ruptured membrane of BAX derived peptide studied by molecular dynamics simulations. J Mol Graph Model 2019; 88:152-159. [PMID: 30703689 DOI: 10.1016/j.jmgm.2019.01.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 01/20/2019] [Accepted: 01/21/2019] [Indexed: 11/19/2022]
Abstract
BAX protein plays a key role in mitochondrial membrane permeabilization and cytochrome c release upon apoptosis. The C-terminal transmembrane domain (TMD) of BAX is supposed to act a membrane anchor when BAX is activated leading to programmed cell death. Previous studies indicate that the C-terminal transmembrane domain of BAX mediates membrane disruption and pore formation, however, the mechanism of the membrane disruption and pore-forming capability of BAX C-terminal transmembrane domain still unclear. Here, we performed all-atom (AA) molecular dynamics simulations to study the membrane effect of TMD peptide. We also conducted coarse-grained (CG) molecular dynamics simulations to study the membrane curvature and the stabilization of ruptured membrane pores effect of TMD peptides. Our results indicated that TMD peptide decreases the local POPC lipids order. The membrane binding of TMD induced a positive membrane curvature, moreover, certain numbers of TMD could stabilize ruptured membrane pore in both CG and AA simulations. These results provide insight into the structure details of membrane pore formation by TMD peptides. The diameters of the pore are qualitatively in good agreement with available experimental data.
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Affiliation(s)
- Zhenyan Jiang
- School of Pharmaceutical Sciences, Jilin University, Changchun, 130021, China
| | - Hansi Zhang
- College of Basic Medical Sciences, Jilin University, Changchun, 130000, China.
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10
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Schneider V, Wadhwani P, Reichert J, Bürck J, Elstner M, Ulrich AS, Kubař T. Tetrameric Charge-Zipper Assembly of the TisB Peptide in Membranes—Computer Simulation and Experiment. J Phys Chem B 2019; 123:1770-1779. [DOI: 10.1021/acs.jpcb.8b12087] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
| | - Parvesh Wadhwani
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P. O. Box 3640, 76021 Karlsruhe, Germany
| | - Johannes Reichert
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P. O. Box 3640, 76021 Karlsruhe, Germany
| | - Jochen Bürck
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P. O. Box 3640, 76021 Karlsruhe, Germany
| | - Marcus Elstner
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P. O. Box 3640, 76021 Karlsruhe, Germany
| | - Anne S. Ulrich
- Institute of Biological Interfaces (IBG-2), Karlsruhe Institute of Technology, P. O. Box 3640, 76021 Karlsruhe, Germany
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11
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Omardien S, Drijfhout JW, Vaz FM, Wenzel M, Hamoen LW, Zaat SA, Brul S. Bactericidal activity of amphipathic cationic antimicrobial peptides involves altering the membrane fluidity when interacting with the phospholipid bilayer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:2404-2415. [DOI: 10.1016/j.bbamem.2018.06.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 06/05/2018] [Accepted: 06/06/2018] [Indexed: 12/22/2022]
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12
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Catte A, Wilson MR, Walker M, Oganesyan VS. Antimicrobial action of the cationic peptide, chrysophsin-3: a coarse-grained molecular dynamics study. SOFT MATTER 2018; 14:2796-2807. [PMID: 29595197 DOI: 10.1039/c7sm02152f] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Antimicrobial peptides (AMPs) are small cationic proteins that are able to destabilize a lipid bilayer structure through one or more modes of action. In this study, we investigate the processes of peptide aggregation and pore formation in lipid bilayers and vesicles by the highly cationic AMP, Chrysophsin-3 (chrys-3), using coarse-grained molecular dynamics (CG-MD) simulations and potential of mean force calculations. We study long 50 μs simulations of chrys-3 at different concentrations, both at the surface of dipalmitoylphosphatidylcholine (DPPC) and palmitoyloleoylphosphatidylcholine (POPC) bilayers, and also interacting within the interior of the lipid membrane. We show that aggregation of peptides at the surface, leads to pronounced deformation of lipid bilayers, leading in turn to lipid protrusions for peptide : ligand ratios > 1 : 12. In addition, aggregation of chrys-3 peptides within the centre of a lipid bilayer leads to spontaneous formation of pores and aggregates. Both mechanisms of interaction are consistent with previously reported experimental data for chrys-3. Similar results are observed also in POPC vesicles and mixed lipid bilayers composed of the zwitterionic lipid palmitoyloleoylphosphatidylethanolamine (POPE) and the negatively charged lipid palmitoyloleoylphosphatidylglycerol (POPG). The latter are employed as models of the bacterial membrane of Escherichia coli.
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Affiliation(s)
- Andrea Catte
- School of Chemistry, University of East Anglia, Norwich, NR4 7TJ, UK.
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13
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Differential Interaction of Antimicrobial Peptides with Lipid Structures Studied by Coarse-Grained Molecular Dynamics Simulations. Molecules 2017; 22:molecules22101775. [PMID: 29053635 PMCID: PMC6151434 DOI: 10.3390/molecules22101775] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 10/17/2017] [Indexed: 01/05/2023] Open
Abstract
In this work; we investigated the differential interaction of amphiphilic antimicrobial peptides with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid structures by means of extensive molecular dynamics simulations. By using a coarse-grained (CG) model within the MARTINI force field; we simulated the peptide-lipid system from three different initial configurations: (a) peptides in water in the presence of a pre-equilibrated lipid bilayer; (b) peptides inside the hydrophobic core of the membrane; and (c) random configurations that allow self-assembled molecular structures. This last approach allowed us to sample the structural space of the systems and consider cooperative effects. The peptides used in our simulations are aurein 1.2 and maculatin 1.1; two well-known antimicrobial peptides from the Australian tree frogs; and molecules that present different membrane-perturbing behaviors. Our results showed differential behaviors for each type of peptide seen in a different organization that could guide a molecular interpretation of the experimental data. While both peptides are capable of forming membrane aggregates; the aurein 1.2 ones have a pore-like structure and exhibit a higher level of organization than those conformed by maculatin 1.1. Furthermore; maculatin 1.1 has a strong tendency to form clusters and induce curvature at low peptide-lipid ratios. The exploration of the possible lipid-peptide structures; as the one carried out here; could be a good tool for recognizing specific configurations that should be further studied with more sophisticated methodologies.
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14
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Structural Behavior of the Peptaibol Harzianin HK VI in a DMPC Bilayer: Insights from MD Simulations. Biophys J 2017. [PMID: 28636916 DOI: 10.1016/j.bpj.2017.05.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Microsecond molecular dynamics simulations of harzianin HK VI (HZ) interacting with a dimyristoylphosphatidylcholine bilayer were performed at the condition of low peptide-to-lipid ratio. Two orientations of HZ molecule in the bilayer were found and characterized. In the orientation perpendicular to the bilayer surface, HZ induces a local thinning of the bilayer. When inserted into the bilayer parallel to its surface, HZ is located nearly completely within the hydrophobic region of the bilayer. A combination of solid-state NMR and circular dichroism experiments found the latter orientation to be dominant. An extended sampling simulation provided qualitative results and showed the same orientation to be a global minimum of free energy. The secondary structure of HZ was characterized, and it was found to be located in the 310-helical family. The specific challenges of computer simulation of nonpolar peptides are discussed briefly.
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15
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Ma H, Cummins DD, Edelstein NB, Gomez J, Khan A, Llewellyn MD, Picudella T, Willsey SR, Nangia S. Modeling Diversity in Structures of Bacterial Outer Membrane Lipids. J Chem Theory Comput 2017; 13:811-824. [DOI: 10.1021/acs.jctc.6b00856] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Huilin Ma
- Department of Biomedical
and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Daniel D. Cummins
- Department of Biomedical
and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Natalie Brooke Edelstein
- Department of Biomedical
and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Jerry Gomez
- Department of Biomedical
and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Aliza Khan
- Department of Biomedical
and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Masud Dikita Llewellyn
- Department of Biomedical
and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Tara Picudella
- Department of Biomedical
and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Sarah Rose Willsey
- Department of Biomedical
and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Shikha Nangia
- Department of Biomedical
and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
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16
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Prince A, Sandhu P, Ror P, Dash E, Sharma S, Arakha M, Jha S, Akhter Y, Saleem M. Lipid-II Independent Antimicrobial Mechanism of Nisin Depends On Its Crowding And Degree Of Oligomerization. Sci Rep 2016; 6:37908. [PMID: 27897200 PMCID: PMC5126574 DOI: 10.1038/srep37908] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 11/02/2016] [Indexed: 02/07/2023] Open
Abstract
Nisin inhibits bacterial growth by generating pores in cell membrane and interrupting cell-wall biosynthesis through specific lipid II interaction. However, the role of the hinge region and C-terminus residues of the peptide in antibacterial action of nisin is largely unknown. Here, using molecular dynamics simulations and experimental approach, we report that at high concentration regimes of nisin, interaction with phospholipids may equally deform the bacterial cell membranes even under significantly varying amounts of lipid-II. Membrane thinning, destabilization and decrease in lipid density depend on the degree of oligomerization of nisin. Growth kinetics of Bacillus subtilis and Escherichia coli interestingly show recovery by extended lag phase under low concentrations of nisin treatment while high concentrations of nisin caused decrease in cell viability as recorded by striking reduction in membrane potential and surface area. The significant changes in the dipole potential and fluorescence anisotropy were observed in negatively charged membranes in the absence of lipid-II with increasing concentration of nisin. The identical correlation of cell viability, membrane potential dissipation and morphology with the concentration regime of nisin, in both Bacillus subtilis (lipid II rich) and Escherichia coli (lipid II impoverished), hints at a non-specific physical mechanism where degree of membrane deformation depends on degree of crowding and oligomerization of nisin.
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Affiliation(s)
- Ashutosh Prince
- Department of Life Sciences, National Institute of Technology, Rourkela, India
| | - Padmani Sandhu
- Centre for Computational Biology and Bioinformatics, School of Life Sciences, Central University of Himachal Pradesh, India
| | - Pankaj Ror
- Department of Life Sciences, National Institute of Technology, Rourkela, India
| | - Eva Dash
- Department of Life Sciences, National Institute of Technology, Rourkela, India
| | - Shingarika Sharma
- Centre for Computational Biology and Bioinformatics, School of Life Sciences, Central University of Himachal Pradesh, India
| | - Manoranjan Arakha
- Department of Life Sciences, National Institute of Technology, Rourkela, India
| | - Suman Jha
- Department of Life Sciences, National Institute of Technology, Rourkela, India
| | - Yusuf Akhter
- Centre for Computational Biology and Bioinformatics, School of Life Sciences, Central University of Himachal Pradesh, India
| | - Mohammed Saleem
- Department of Life Sciences, National Institute of Technology, Rourkela, India
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17
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King MJ, Bennett AL, Almeida PF, Lee HS. Coarse-grained simulations of hemolytic peptide δ-lysin interacting with a POPC bilayer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:3182-3194. [PMID: 27720634 DOI: 10.1016/j.bbamem.2016.10.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 09/17/2016] [Accepted: 10/04/2016] [Indexed: 01/08/2023]
Abstract
δ-lysin, secreted by a Gram-positive bacterium Staphylococcus aureus, is a 26-residue membrane active peptide that shares many common features with antimicrobial peptides (AMPs). However, it possesses a few unique features that differentiate itself from typical AMPs. In particular, δ-lysin has zero net charge, even though it has many charged residues, and it preferentially lyses eukaryotic cells over bacterial cells. Here, we present the results of coarse-grained molecular dynamics simulations of δ-lysin interacting with a zwitterionic membrane over a wide range of peptide concentrations. When the peptides concentration is low, spontaneous dimerization of peptides is observed on the membrane surface, but deep insertion of peptides or pore formation was not observed. However, the calculated free energy of peptide insertion suggests that a small fraction of peptides is likely to be present inside the membrane at the peptide concentrations typically seen in dye efflux experiments. When the simulations with multiple peptides are carried out with a single pre-inserted transmembrane peptide, spontaneous pore formation occurs with a peptide-to-lipid ratio (P/L) as low as P/L=1:42. Inter-peptide salt bridges among the transmembrane peptides seem to play a role in creating compact pores with very low level of hydration. More importantly, the transmembrane peptides making up the pore are constantly pushed to the opposite side of the membrane when the mass imbalance between the two sides of membrane is significant. Thus, the pore is very dynamic, allowing multiple peptides to translocate across the membrane simultaneously.
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Affiliation(s)
- Mariah J King
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28403, United States
| | - Ashley L Bennett
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28403, United States
| | - Paulo F Almeida
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28403, United States
| | - Hee-Seung Lee
- Department of Chemistry and Biochemistry, University of North Carolina Wilmington, Wilmington, NC 28403, United States.
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18
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Scherer KM, Spille JH, Sahl HG, Grein F, Kubitscheck U. The lantibiotic nisin induces lipid II aggregation, causing membrane instability and vesicle budding. Biophys J 2015; 108:1114-24. [PMID: 25762323 PMCID: PMC4375720 DOI: 10.1016/j.bpj.2015.01.020] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 12/19/2014] [Accepted: 01/23/2015] [Indexed: 10/23/2022] Open
Abstract
The antimicrobial peptide nisin exerts its activity by a unique dual mechanism. It permeates the cell membranes of Gram-positive bacteria by binding to the cell wall precursor Lipid II and inhibits cell wall synthesis. Binding of nisin to Lipid II induces the formation of large nisin-Lipid II aggregates in the membrane of bacteria as well as in Lipid II-doped model membranes. Mechanistic details of the aggregation process and its impact on membrane permeation are still unresolved. In our experiments, we found that fluorescently labeled nisin bound very inhomogeneously to bacterial membranes as a consequence of the strong aggregation due to Lipid II binding. A correlation between cell membrane damage and nisin aggregation was observed in vivo. To further investigate the aggregation process of Lipid II and nisin, we assessed its dynamics by single-molecule microscopy of fluorescently labeled Lipid II molecules in giant unilamellar vesicles using light-sheet illumination. We observed a continuous reduction of Lipid II mobility due to a steady growth of nisin-Lipid II aggregates as a function of time and nisin concentration. From the measured diffusion constants of Lipid II, we estimated that the largest aggregates contained tens of thousands of Lipid II molecules. Furthermore, we observed that the formation of large nisin-Lipid II aggregates induced vesicle budding in giant unilamellar vesicles. Thus, we propose a membrane permeation mechanism that is dependent on the continuous growth of nisin-Lipid II aggregation and probably involves curvature effects on the membrane.
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Affiliation(s)
- Katharina M Scherer
- Institute for Physical and Theoretical Chemistry, Pharmaceutical Microbiology Unit, Rheinische Friedrich-Wilhelms University Bonn, Bonn, Germany.
| | - Jan-Hendrik Spille
- Institute for Physical and Theoretical Chemistry, Pharmaceutical Microbiology Unit, Rheinische Friedrich-Wilhelms University Bonn, Bonn, Germany
| | - Hans-Georg Sahl
- Institute for Medical Microbiology, Immunology and Parasitology, Pharmaceutical Microbiology Unit, Rheinische Friedrich-Wilhelms University Bonn, Bonn, Germany
| | - Fabian Grein
- Institute for Medical Microbiology, Immunology and Parasitology, Pharmaceutical Microbiology Unit, Rheinische Friedrich-Wilhelms University Bonn, Bonn, Germany
| | - Ulrich Kubitscheck
- Institute for Physical and Theoretical Chemistry, Pharmaceutical Microbiology Unit, Rheinische Friedrich-Wilhelms University Bonn, Bonn, Germany
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19
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Abstract
The rapid spread of drug-resistant pathogenic microbial strains has created an urgent need for the development of new anti-infective molecules, having different mechanism of action in comparison to existing drugs. Natural antimicrobial peptides (AMPs) represent a novel class of molecules with a broad spectrum of activity and a low rate in inducing bacterial resistance. In particular, linear alpha-helical cationic antimicrobial peptides are among the most widespread membrane-disruptive AMPs in nature, representing a particularly successful structural arrangement of the innate defense against microbes. However, until now, many AMPs have failed in clinical trials because of several drawbacks that strongly limit their applicability such as degradation, cytotoxicity, and high production cost. Thus, to overcome the limitations of native peptides, a rational in silico approach to AMPs design becomes a promising strategy that drastically reduce production costs and the time required for evaluation of activity and toxicity. This chapter focuses on the strategies and methods for de novo design of potentially active AMPs. In particular, statistical-based design strategies and MD methods for modelling AMPs are elucidated.
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Affiliation(s)
- Giuseppe Maccari
- Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Pisa, Italy
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20
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Goliaei A, Santo KP, Berkowitz ML. Local pressure changes in lipid bilayers due to adsorption of melittin and magainin-h2 antimicrobial peptides: results from computer simulations. J Phys Chem B 2014; 118:12673-9. [PMID: 25299589 DOI: 10.1021/jp507919p] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We performed a series of coarse-grained computer simulations in order to study how the placement of melittin and magainin-h2 antimicrobial peptides on the surface of the bilayer changes the local pressure profiles in the bilayer. The simulations were done using the NPT ensemble when the total stress on the bilayer was zero and also using the NP(z)AT ensemble, with a nonzero total stress. In the NPT ensemble, although the total stress was zero, each leaflet of the bilayer experienced a nonzero stress, and the stresses are equal by magnitude, but opposite in their direction. The observed stresses acting on the monolayers may cause the rupture of the monolayers to release the stress. Our simulations were done at different peptide to lipid ratio (P/L). When the P/L ratio was 1/50 there was no large difference in the local pressure profile for bilayers with melittin versus bilayers with magainin-h2. When simulations were performed in the NP(z)AT ensemble at P/L = 3/100 we observed a large difference in the pressure profiles in the bilayers with melittin peptides compared to the bilayer with magainin-h2. The observed in this case difference in stress may explain the difference in actions of melittin and magainin at high P/L.
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Affiliation(s)
- Ardeshir Goliaei
- Department of Biochemistry and Biophysics and Program in Molecular and Cellular Biophysics, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States
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21
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Wang KF, Nagarajan R, Camesano TA. Differentiating antimicrobial peptides interacting with lipid bilayer: Molecular signatures derived from quartz crystal microbalance with dissipation monitoring. Biophys Chem 2014; 196:53-67. [PMID: 25307196 DOI: 10.1016/j.bpc.2014.09.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Revised: 09/16/2014] [Accepted: 09/16/2014] [Indexed: 10/24/2022]
Abstract
Many antimicrobial peptides (AMPs) kill bacteria by disrupting the lipid bilayer structure of their inner membrane. However, there is only limited quantitative information in the literature to differentiate between AMPs of differing molecular properties, in terms of how they interact with the membrane. In this study, we have used quartz crystal microbalance with dissipation monitoring (QCM-D) to probe the interactions between a supported bilayer membrane of egg phosphatidylcholine (egg PC) and four structurally different AMPs: alamethicin, chrysophsin-3, indolicidin, and sheep myeloid antimicrobial peptide (SMAP-29). Multiple signatures from the QCM-D measurements were extracted, differentiating the AMPs, that provide information on peptide addition to and lipid removal from the membrane, the dynamics of peptide-membrane interactions and the rates at which the peptide actions are initiated. The mechanistic variations in peptide action were related to the fundamental structural properties of the peptides including the hydrophobicity, hydrophobic moment, and the probability of α-helical secondary structures.
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Affiliation(s)
- Kathleen F Wang
- Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609, United States
| | - Ramanathan Nagarajan
- Molecular Sciences and Engineering Team, Natick Soldier Research, Development and Engineering Center, Natick, MA 01760, United States.
| | - Terri A Camesano
- Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609, United States
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22
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The cooperative behaviour of antimicrobial peptides in model membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2870-81. [PMID: 25046254 DOI: 10.1016/j.bbamem.2014.07.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Revised: 06/27/2014] [Accepted: 07/01/2014] [Indexed: 01/24/2023]
Abstract
A systematic analysis of the hypothesis of the antimicrobial peptides' (AMPs) cooperative action is performed by means of full atomistic molecular dynamics simulations accompanied by circular dichroism experiments. Several AMPs from the aurein family (2.5,2.6, 3.1), have a similar sequence in the first ten amino acids, are investigated in different environments including aqueous solution, trifluoroethanol (TFE), palmitoyloleoylphosphatidylethanolamine (POPE), and palmitoyloleoylphosphatidylglycerol (POPG) lipid bilayers. It is found that the cooperative effect is stronger in aqueous solution and weaker in TFE. Moreover, in the presence of membranes, the cooperative effect plays an important role in the peptide/lipid bilayer interaction. The action of AMPs is a competition of the hydrophobic interactions between the side chains of the peptides and the hydrophobic region of lipid molecules, as well as the intra peptide interaction. The aureins 2.5-COOH and 2.6-COOH form a hydrophobic aggregate to minimize the interaction between the hydrophobic group and the water. Once that the peptides reach the water/lipid interface the hydrophobic aggregate becomes smaller and the peptides start to penetrate into the membrane. In contrast, aurein 3.1-COOH forms only a transient aggregate which disintegrates once the peptides reached the membrane, and it shows no cooperativity in membrane penetration.
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23
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Di Luca M, Maccari G, Nifosì R. Treatment of microbial biofilms in the post-antibiotic era: prophylactic and therapeutic use of antimicrobial peptides and their design by bioinformatics tools. Pathog Dis 2014; 70:257-70. [PMID: 24515391 DOI: 10.1111/2049-632x.12151] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 01/22/2014] [Accepted: 01/30/2014] [Indexed: 12/14/2022] Open
Abstract
The treatment for biofilm infections is particularly challenging because bacteria in these conditions become refractory to antibiotic drugs. The reduced effectiveness of current therapies spurs research for the identification of novel molecules endowed with antimicrobial activities and new mechanisms of antibiofilm action. Antimicrobial peptides (AMPs) have been receiving increasing attention as potential therapeutic agents, because they represent a novel class of antibiotics with a wide spectrum of activity and a low rate in inducing bacterial resistance. Over the past decades, a large number of naturally occurring AMPs have been identified or predicted from various organisms as effector molecules of the innate immune system playing a crucial role in the first line of defense. Recent studies have shown the ability of some AMPs to act against microbial biofilms, in particular during early phases of biofilm development. Here, we provide a review of the antimicrobial peptides tested on biofilms, highlighting their advantages and disadvantages for prophylactic and therapeutic applications. In addition, we describe the strategies and methods for de novo design of potentially active AMPs and discuss how informatics and computational tools may be exploited to improve antibiofilm effectiveness.
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24
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Santo KP, Irudayam SJ, Berkowitz ML. Melittin creates transient pores in a lipid bilayer: results from computer simulations. J Phys Chem B 2013; 117:5031-42. [PMID: 23534858 DOI: 10.1021/jp312328n] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To study the interaction between melittin peptides and lipid bilayer, we performed coarse-grained simulations on systems containing melittin interacting with a bilayer containing zwitterionic dipalmitoylphosphatidylcholine (DPPC) and anionic palmitoyloleoylphosphatidylglycerol (POPG) phospholipids in a 7:3 ratio. Eight different systems were considered: four at low and four at high peptide to lipid (P/L) ratios. In case of low P/L ratio we did not observe any pore creation in the bilayer. In two out of four of the simulations with the high P/L ratio, appearance of transient pores in the bilayer was observed. These pores were created due to an assembly of 3-5 melittin peptides. Not all of the peptides in the pores were in a transmembrane conformation; many of them had their termini residues anchored to the same leaflet, and these peptides assumed bent, U-shaped, conformations. We propose that when an assembly of melittin peptides creates pores, such an assembly acts as a "wedge" that splits the bilayer. To get a more detailed description of melittin on the bilayer surface and in transient pores, we performed coarse-grained to united-atom scale transformations and after that performed 50 ns molecular dynamics simulations using the united atom description of the systems. While these simulations did not show much of the change in the pore structure during the 50 ns time interval, they clearly showed the presence of water in the transient pores. The appearance of transient pores together with the translocation of peptides across the membranes is consistent with the mechanism proposed to explain graded dye leakage from large vesicles in the presence of melittin.
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Affiliation(s)
- Kolattukudy P Santo
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599, United States
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25
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Li J, Liu S, Lakshminarayanan R, Bai Y, Pervushin K, Verma C, Beuerman RW. Molecular simulations suggest how a branched antimicrobial peptide perturbs a bacterial membrane and enhances permeability. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:1112-21. [PMID: 23274275 DOI: 10.1016/j.bbamem.2012.12.015] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Revised: 12/03/2012] [Accepted: 12/18/2012] [Indexed: 11/29/2022]
Abstract
A covalently, branched antimicrobial peptide (BAMP) B2088 demonstrating enhanced antimicrobial effects and without additional toxicity when compared to its linear counterpart, has been developed. Atomistic molecular dynamics simulations have been used to investigate the mode of interaction of B2088 with model bacterial and mammalian membranes. These simulations suggest that both long-range electrostatic interactions and short-range hydrogen bonding play important roles in steering B2088 toward the negatively charged membranes. The reason why B2088 is selective towards the bacterial membrane is postulated to be the greater density of negative charges on the bacterial membrane which enables rapid accumulation of B2088 on the bacterial membrane to a high surface concentration, stabilizing it through excess hydrogen bond formation. The majority of hydrogen bonds are seen between the side chains of the basic residues (Arg or Lys) with the PO4 groups of lipids. In particular, formation of the bidentate hydrogen bonds between the guanidinium group of Arg and PO4 groups are found to be more favorable, both geometrically and energetically. Moreover, the planar gaunidinium group and its hydrophobic character enable the Arg side chains to solvate into the hydrophobic membrane. Structural perturbation of the bacterial membrane is found to be concentration dependent and is significant at higher concentrations of B2088, resulting in a large number of water translocations across the bacterial membrane. These simulations enhance our understanding of the action mechanism of a covalently branched antimicrobial peptide with model membranes and provide practical guidance for the design of new antimicrobial peptides.
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Affiliation(s)
- Jianguo Li
- Singapore Eye Research Institute, Singapore, Singapore
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26
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Irudayam SJ, Berkowitz ML. Binding and reorientation of melittin in a POPC bilayer: computer simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2975-81. [PMID: 22877705 DOI: 10.1016/j.bbamem.2012.07.026] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 07/26/2012] [Accepted: 07/27/2012] [Indexed: 11/26/2022]
Abstract
We performed, using an all-atom force field, molecular dynamics computer simulations to study the binding of melittin to the POPC bilayer and its subsequent reorientation in this bilayer. The binding process involves a simultaneous folding and adsorption of the peptide to the bilayer, followed by the creation of a "U shaped" conformation. The reorientation of melittin from the parallel to the perpendicular conformation requires charged residues to cross the hydrophobic core of the bilayer. This is accomplished by a creation of defects in the bilayer that are filled out with water. The defects are caused by peptide charged residues dragging the lipid headgroup atoms along with them, as they reorient. With increased concentration of melittin water defects form stable pores; this makes it easier for the peptide N-terminus to reorient. Our results complement experimental and computational observations of the melittin/lipid bilayer interaction.
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Affiliation(s)
- Sheeba J Irudayam
- Department of Chemistry, University of North Carolina at Chapel Hill, North Carolina, NC 27599, USA.
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