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Veretenenko II, Trofimov YA, Krylov NA, Efremov RG. Nanoscale lipid domains determine the dynamic molecular portraits of mixed DOPC/DOPS bilayers in a fluid phase: A computational insight. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184376. [PMID: 39111381 DOI: 10.1016/j.bbamem.2024.184376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Revised: 08/01/2024] [Accepted: 08/01/2024] [Indexed: 08/12/2024]
Abstract
Lateral heterogeneity, or mosaicity, is a fundamental property inherent to cell membranes that is crucial for their functioning. While microscopic inhomogeneities (e.g. rafts) are easily detected experimentally, lipid domains with nanoscale dimensions (nanoclusters of nanodomains, NDs) resist reliable characterization by instrumental methods. In such a case, important insight can be gained via computer modeling. Here, NDs composed of lipid's head groups in the mixed zwitterionic dioleoylphosphatidylcholine (DOPC) and negatively charged dioleoylphosphatidylserine (DOPS) bilayers were studied by molecular dynamics. A new algorithm has been developed to identify NDs. Unlike most similar methods, it implicitly considers the heterogeneous distribution of lipid head atomic density and does not require subjectively chosen parameters. In DOPS-rich membranes, lipids form more compact and stable NDs due to strong interlipid interactions. In DOPC-rich systems, NDs arise due to the "packing" effect of weakly bound lipid heads. The clustering picture is related to the physical properties of the bilayer surface: DOPS-rich systems show more pronounced surface heterogeneity of hydrophilic/hydrophobic regions compared to DOPC-rich ones. The results obtained are important for the effective quantitative characterization of the "dynamic molecular portrait" of a membrane surface - its "fingerprint" characterizing dynamical distribution of its physicochemical properties.
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Affiliation(s)
- Irina I Veretenenko
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia; Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow region 141701, Russia.
| | - Yury A Trofimov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Nikolay A Krylov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia
| | - Roman G Efremov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia; Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow region 141701, Russia; National Research University Higher School of Economics, Moscow 101000, Russia.
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2
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Zhao M, Lopes LJS, Sahni H, Yadav A, Do HN, Reddy T, López CA, Neale C, Gnanakaran S. Insertion and Anchoring of HIV-1 Fusion Peptide into Complex Membrane Mimicking Human T-cell. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.02.606381. [PMID: 39131401 PMCID: PMC11312619 DOI: 10.1101/2024.08.02.606381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/13/2024]
Abstract
A fundamental understanding of how HIV-1 envelope (Env) protein facilitates fusion is still lacking. The HIV-1 fusion peptide, consisting of 15 to 22 residues, is the N-terminus of the gp41 subunit of the Env protein. Further, this peptide, a promising vaccine candidate, initiates viral entry into target cells by inserting and anchoring into human immune cells. The influence of membrane lipid reorganization and the conformational changes of the fusion peptide during the membrane insertion and anchoring processes, which can significantly affect HIV-1 cell entry, remains largely unexplored due to the limitations of experimental measurements. In this work, we investigate the insertion of the fusion peptide into an immune cell membrane mimic through multiscale molecular dynamics simulations. We mimic the native T-cell by constructing a 9-lipid asymmetric membrane, along with geometrical restraints accounting for insertion in the context of gp41. To account for the slow timescale of lipid mixing while enabling conformational changes, we implement a protocol to go back and forth between atomistic and coarse-grained simulations. Our study provides a molecular understanding of the interactions between the HIV-1 fusion peptide and the T-cell membrane, highlighting the importance of conformational flexibility of fusion peptides and local lipid reorganization in stabilizing the anchoring of gp41 into the targeted host membrane during the early events of HIV-1 cell entry. Importantly, we identify a motif within the fusion peptide critical for fusion that can be further manipulated in future immunological studies.
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Affiliation(s)
- Mingfei Zhao
- T-6 Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos NM USA
| | | | - Harshita Sahni
- T-6 Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos NM USA
- Department of Computer Science, University of New Mexico, Albuquerque NM, USA
| | - Anju Yadav
- T-6 Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos NM USA
- Department of Chemistry and Biochemistry, University of Texas at El Paso, El Paso TX, USA
| | - Hung N Do
- T-6 Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos NM USA
| | - Tyler Reddy
- CCS-7 Applied Computer Science Group, Los Alamos National Laboratory, Los Alamos NM USA
| | - Cesar A López
- T-6 Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos NM USA
| | - Chris Neale
- T-6 Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos NM USA
| | - S Gnanakaran
- T-6 Theoretical Biology and Biophysics, Los Alamos National Laboratory, Los Alamos NM USA
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3
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Lihan M, Tajkhorshid E. Improved Highly Mobile Membrane Mimetic Model for Investigating Protein-Cholesterol Interactions. J Chem Inf Model 2024; 64:4822-4834. [PMID: 38844760 DOI: 10.1021/acs.jcim.4c00619] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/25/2024]
Abstract
Cholesterol (CHL) plays an integral role in modulating the function and activity of various mammalian membrane proteins. Due to the slow dynamics of lipids, conventional computational studies of protein-CHL interactions rely on either long-time scale atomistic simulations or coarse-grained approximations to sample the process. A highly mobile membrane mimetic (HMMM) has been developed to enhance lipid diffusion and thus used to facilitate the investigation of lipid interactions with peripheral membrane proteins and, with customized in silico solvents to replace phospholipid tails, with integral membrane proteins. Here, we report an updated HMMM model that is able to include CHL, a nonphospholipid component of the membrane, henceforth called HMMM-CHL. To this end, we had to optimize the effect of the customized solvents on CHL behavior in the membrane. Furthermore, the new solvent is compatible with simulations using force-based switching protocols. In the HMMM-CHL, both improved CHL dynamics and accelerated lipid diffusion are integrated. To test the updated model, we have applied it to the characterization of protein-CHL interactions in two membrane protein systems, the human β2-adrenergic receptor (β2AR) and the mitochondrial voltage-dependent anion channel 1 (VDAC-1). Our HMMM-CHL simulations successfully identified CHL binding sites and captured detailed CHL interactions in excellent consistency with experimental data as well as other simulation results, indicating the utility of the improved model in applications where an enhanced sampling of protein-CHL interactions is desired.
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Affiliation(s)
- Muyun Lihan
- Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
- NIH Center for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Emad Tajkhorshid
- Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
- NIH Center for Macromolecular Modeling and Visualization, Beckman Institute for Advanced Science and Technology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Biochemistry, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, United States
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4
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Shagurin A, Miannay FA, Kiselev MG, Jedlovszky P, Affouard F, Idrissi A. Widom Line in Supercritical Water in Terms of Changes in Local Structure: Theoretical Perspective. J Phys Chem Lett 2024; 15:5831-5837. [PMID: 38787641 DOI: 10.1021/acs.jpclett.4c01142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2024]
Abstract
Performing molecular dynamics simulations with the TIP4P/2005 water model along 9 isobars (from 175 to 375 bar) in the temperature range between 300 and 1100 K, we have found that the loci of the extrema in the rate of change of specific structural properties can be used to define purely structure-based Widom lines. We have examined several parameters that describe the local structure of water, such as the tetrahedral arrangement, nearest neighbor distance, local density around the molecules, and the size of the largest dense domain. The last two parameters were determined using the Voronoi polyhedral and density-based spatial clustering of applications with noise methods, respectively. By analyzing the moments of the associated distributions, we show that along a given isobar, the temperature at which we observe a maximum in the fluctuation, the rate of change of the average values, or in the skewness values unambiguously determines the Widom line that is in agreement with the experimentally detected, thermodynamic response function-based ones.
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Affiliation(s)
- Artem Shagurin
- University of Lille, CNRS UMR 8516 -LASIRe - Laboratoire Avancé de Spectroscopie pour les Interactions la Réactivité et l'environnement, 59000 Lille, France
- Univ. Lille, CNRS, INRAE, Centrale Lille, UMR 8207 - UMET - Unité Matériaux et Transformations, F-59000 Lille, France
- Krestov Institute of Solution Chemistry, Russian Academy of Sciences, Ivanovo, 153045 Russia
| | - Francois A Miannay
- University of Lille, CNRS UMR 8516 -LASIRe - Laboratoire Avancé de Spectroscopie pour les Interactions la Réactivité et l'environnement, 59000 Lille, France
| | - Michael G Kiselev
- Krestov Institute of Solution Chemistry, Russian Academy of Sciences, Ivanovo, 153045 Russia
| | - Pal Jedlovszky
- Department of Chemistry, Eszterházy Károly Catholic University, Leányka u. 6, 3300 Eger, Hungary
| | - Frederic Affouard
- Univ. Lille, CNRS, INRAE, Centrale Lille, UMR 8207 - UMET - Unité Matériaux et Transformations, F-59000 Lille, France
| | - Abdenacer Idrissi
- University of Lille, CNRS UMR 8516 -LASIRe - Laboratoire Avancé de Spectroscopie pour les Interactions la Réactivité et l'environnement, 59000 Lille, France
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5
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Sharma P, Vaiwala R, Gopinath AK, Chockalingam R, Ayappa KG. Structure of the Bacterial Cell Envelope and Interactions with Antimicrobials: Insights from Molecular Dynamics Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:7791-7811. [PMID: 38451026 DOI: 10.1021/acs.langmuir.3c03474] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
Bacteria have evolved over 3 billion years, shaping our intrinsic and symbiotic coexistence with these single-celled organisms. With rising populations of drug-resistant strains, the search for novel antimicrobials is an ongoing area of research. Advances in high-performance computing platforms have led to a variety of molecular dynamics simulation strategies to study the interactions of antimicrobial molecules with different compartments of the bacterial cell envelope of both Gram-positive and Gram-negative species. In this review, we begin with a detailed description of the structural aspects of the bacterial cell envelope. Simulations concerned with the transport and associated free energy of small molecules and ions through the outer membrane, peptidoglycan, inner membrane and outer membrane porins are discussed. Since surfactants are widely used as antimicrobials, a section is devoted to the interactions of surfactants with the cell wall and inner membranes. The review ends with a discussion on antimicrobial peptides and the insights gained from the molecular simulations on the free energy of translocation. Challenges involved in developing accurate molecular models and coarse-grained strategies that provide a trade-off between atomic details with a gain in sampling time are highlighted. The need for efficient sampling strategies to obtain accurate free energies of translocation is also discussed. Molecular dynamics simulations have evolved as a powerful tool that can potentially be used to design and develop novel antimicrobials and strategies to effectively treat bacterial infections.
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Affiliation(s)
- Pradyumn Sharma
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
| | - Rakesh Vaiwala
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
| | - Amar Krishna Gopinath
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
| | - Rajalakshmi Chockalingam
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
| | - K Ganapathy Ayappa
- Department of Chemical Engineering, Indian Institute of Science, Bangalore, Karnataka, India, 560012
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6
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Doktorova M, Khelashvili G, Brown MF. Efficient calculation of orientation-dependent lipid dynamics from membrane simulations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.05.23.542012. [PMID: 37292992 PMCID: PMC10245828 DOI: 10.1101/2023.05.23.542012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Molecular dynamics simulations of lipid membranes have become increasingly impactful in biophysics because they offer atomistic resolution of structural fluctuations in relation to their functional outputs. Yet quantitative characterization of multiscale processes is a formidable challenge due to the distribution of motions that evade analysis of discrete simulation data. Here we investigate the efficient calculation of CH bond relaxation rates from membrane simulations. Widely used computational approaches offer numerical simplicity but fall short of capturing crucial aspects of the orientation dependence of the dynamics. To circumvent this problem, we introduced a robust framework based on liquid crystal theory which considers explicitly the CH bond motions with respect to the director axis (bilayer normal). Analysis of the orientation dependence of the dynamics shows excellent agreement with experiment, illustrating how the ordering potential affects the calculated relaxation rates. Furthermore, a fit-based resampling of the autocorrelation function of the bond fluctuations validates the new approach for low-temporal resolution data. The recovered relaxation rates indicate that at short timescales, both with and without cholesterol, the local motions of CH bonds describe the bilayer microviscosity and resemble liquid hydrocarbons. Our results establish the critical role of the orientational anisotropy in analysis of membrane simulations, explain fundamental aspects of lipid dynamics, and provide guidelines for extracting information that can be compared to experimental data.
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Affiliation(s)
- Milka Doktorova
- Department of Molecular Physiology & Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - George Khelashvili
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, NY, USA
- Institute of Computational Biomedicine, Weill Cornell Medical College of Cornell University, New York, NY, USA
| | - Michael F. Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA
- Department of Physics, University of Arizona, Tucson, AZ, USA
- Program in Applied Mathematics, University of Arizona, Tucson, AZ, USA
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7
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Lam CK, Fung LY, Wang Y. Orientation and Membrane Partition Free Energy of PeT-Based Voltage-Sensitive Dyes from Molecular Simulations. J Phys Chem B 2024; 128:2734-2744. [PMID: 38459942 PMCID: PMC10961725 DOI: 10.1021/acs.jpcb.3c08090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 02/19/2024] [Accepted: 02/20/2024] [Indexed: 03/11/2024]
Abstract
Voltage measurement via small-molecule fluorescent indicators is a valuable approach in deciphering complex dynamics in electrically excitable cells. However, our understanding of various physicochemical properties governing the performance of fluorescent voltage sensors based on the photoinduced electron transfer (PeT) mechanism remains incomplete. Here, through extensive molecular dynamics and free energy calculations, we systematically examine the orientation and membrane partition of three PeT-based voltage-sensing VoltageFluor (VF) dyes in different lipid environment. We show that the symmetry of the molecular scaffold and the net charge of the hydrophilic headgroup of a given VF dye dominate its orientation and membrane partition, respectively. Our work provides a mechanistic understanding of the physical properties contributing to the voltage sensitivity, signal-to-noise ratio, as well as membrane distribution of VF dyes and sheds light onto rational design principles of PeT-based fluorescent probes in general.
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Affiliation(s)
- Chun Kei Lam
- Department of Physics, The
Chinese University
of Hong Kong, Shatin, Hong Kong SAR, China
| | - Lap Yan Fung
- Department of Physics, The
Chinese University
of Hong Kong, Shatin, Hong Kong SAR, China
| | - Yi Wang
- Department of Physics, The
Chinese University
of Hong Kong, Shatin, Hong Kong SAR, China
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8
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van Tilburg MA, Marrink SJ, König M, Grünewald F. Shocker─A Molecular Dynamics Protocol and Tool for Accelerating and Analyzing the Effects of Osmotic Shocks. J Chem Theory Comput 2024; 20:212-223. [PMID: 38109481 PMCID: PMC10782443 DOI: 10.1021/acs.jctc.3c00961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 11/23/2023] [Accepted: 11/29/2023] [Indexed: 12/20/2023]
Abstract
The process of osmosis, a fundamental phenomenon in life, drives water through a semipermeable membrane in response to a solute concentration gradient across this membrane. In vitro, osmotic shocks are often used to drive shape changes in lipid vesicles, for instance, to study fission events in the context of artificial cells. While experimental techniques provide a macroscopic picture of large-scale membrane remodeling processes, molecular dynamics (MD) simulations are a powerful tool to study membrane deformations at the molecular level. However, simulating an osmotic shock is a time-consuming process due to slow water diffusion across the membrane, making it practically impossible to examine its effects in classic MD simulations. In this article, we present Shocker, a Python-based MD tool for simulating the effects of an osmotic shock by selecting and relocating water particles across a membrane over the course of several pumping cycles. Although this method is primarily aimed at efficiently simulating volume changes in vesicles, it can also handle membrane tubes and double bilayer systems. Additionally, Shocker is force field-independent and compatible with both coarse-grained and all-atom systems. We demonstrate that our tool is applicable to simulate both hypertonic and hypotonic osmotic shocks for a range of vesicular and bilamellar setups, including complex multicomponent systems containing membrane proteins or crowded internal solutions.
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Affiliation(s)
- Marco
P. A. van Tilburg
- Groningen
Biomolecular Sciences and Biotechnology Institute and Zernike Institute
for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Siewert J. Marrink
- Groningen
Biomolecular Sciences and Biotechnology Institute and Zernike Institute
for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Melanie König
- Groningen
Biomolecular Sciences and Biotechnology Institute and Zernike Institute
for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Fabian Grünewald
- Groningen
Biomolecular Sciences and Biotechnology Institute and Zernike Institute
for Advanced Materials, University of Groningen, 9747 AG Groningen, The Netherlands
- Heidelberg
Institute for Theoretical Studies (HITS), Schloss-Wolfsbrunnenweg 35, 69118 Heidelberg, Germany
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9
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Cao Z, Zhao L, Chen M, Shi Z, Liu L. Molecular mechanism of calcitriol enhances membrane water permeability. Biochim Biophys Acta Mol Cell Biol Lipids 2024; 1869:159430. [PMID: 37979445 DOI: 10.1016/j.bbalip.2023.159430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 11/12/2023] [Accepted: 11/13/2023] [Indexed: 11/20/2023]
Abstract
Helicobacter pylori (H. pylori) exhibits a unique membrane lipid composition, including dimyristoyl phosphatidylethanolamine (DMPE) and cholesterol, unlike other Gram-negative bacteria. Calcitriol has antimicrobial activity against H. pylori, but cholesterol enhances antibiotics resistance in H. pylori. This study explored the changes in membrane structure and the molecular mechanisms of cholesterol/calcitriol translocation using well-tempered metadynamics (WT-MetaD) simulations and microsecond conventional molecular dynamics (CMD) simulations. Calcitriol facilitated water transport across the membrane, while cholesterol had the opposite effect. The differing effects might result from the tail 25-hydroxyl group and a wider range of orientations of calcitriol in the DMPE/dimyristoyl phosphatidylglycerol (DMPG) (3:1) membrane. Calcitriol moves across the bilayer center without changing its orientation along the membrane Z-axis, becomes parallel to the membrane surface at the membrane-water interface, and then rotates approximately 90° in this interface. The translocation mechanism of calcitriol is quite different from the flip-flop of cholesterol. Moreover, calcitriol crossed from one layer to another more easily than cholesterol, causing successive perturbations to the hydrophobic core and increasing water permeation. These results improve our understanding of the relationship between cholesterol/calcitriol concentrations and the lipid bilayer structure and the role of lipid composition in water permeation.
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Affiliation(s)
- Zanxia Cao
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China.
| | - Liling Zhao
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China
| | - Mingcui Chen
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China
| | - Zhihong Shi
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China
| | - Lei Liu
- Shandong Provincial Key Laboratory of Biophysics, Institute of Biophysics, Dezhou University, Dezhou 253023, China.
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10
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Malaspina DC, Teixidor F, Viñas C, Faraudo J. How a few help all: cooperative crossing of lipid membranes by COSAN anions. Phys Chem Chem Phys 2023; 25:27942-27948. [PMID: 37823330 DOI: 10.1039/d3cp03614f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/13/2023]
Abstract
Experimental results show that the presence of a concentration gradient of certain nano-ions (most notably cobaltabisdicarbollide ([o-COSAN]- anions), induce a current across intact artificial phospholipid bilayers in spite of the high Born free energy estimated for these ions. The mechanism underlying this observed translocation of nano-anions across membranes has yet to be determined. Here we show, using molecular dynamics simulations, that the permeation of [o-COSAN]- anions across a lipid bilayer proceeds in a cooperative manner. Single nano-ions can enter the bilayer but permeation is hampered by a free energy barrier of about 8kBT. The interaction between these nano-ions inside a leaflet induces a flip-flop translocation mechanism with the formation of transient, elongated structure inside the membrane. This cooperative flip-flop allows an efficient distribution of [o-COSAN]- anions in both leaflets of the bilayer. These results suggest the existence of a new mechanism for permeation of nano-ions across lipid membranes, relevant for those that have the appropriate self-assembly character.
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Affiliation(s)
- David C Malaspina
- Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, E- 08193, Bellaterra, Spain.
| | - Francesc Teixidor
- Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, E- 08193, Bellaterra, Spain.
| | - Clara Viñas
- Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, E- 08193, Bellaterra, Spain.
| | - Jordi Faraudo
- Institut de Ciencia de Materials de Barcelona, ICMAB-CSIC, Campus de la UAB, E- 08193, Bellaterra, Spain.
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11
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Mahato DR, Andersson M. Dynamic lipid interactions in the plasma membrane Na +,K +-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119545. [PMID: 37481079 DOI: 10.1016/j.bbamcr.2023.119545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 06/12/2023] [Accepted: 07/13/2023] [Indexed: 07/24/2023]
Abstract
The function of ion-transporting Na+,K+-ATPases depends on the surrounding lipid environment in biological membranes. Two established lipid-interaction sites A and B within the transmembrane domain have been observed to induce protein activation and stabilization, respectively. In addition, lipid-mediated inhibition has been assigned to a site C, but with the exact location not experimentally confirmed. Also, possible effects on lipid interactions by disease mutants dwelling in the membrane-protein interface remain relatively uncharacterized. We simulated human Na+,K+-ATPase α1β1FXYD homology models in E1 and E2 states in an asymmetric, multicomponent plasma membrane to determine both wild-type and disease mutant lipid-protein interactions. The simulated wild-type lipid interactions at the established sites A and B were in agreement with experimental results thereby confirming the membrane-protein model system. The less well-characterized, proposed inhibitory site C was dominated by lipids lacking inhibitory properties. Instead, two sites hosting inhibitory lipids were identified at the extracellular side and also a cytoplasmic CHL-binding site that provide putative alternative locations of Na+,K+-ATPase inhibition. Three disease mutations, Leu302Arg, Glu840Arg and Met859Arg resided in the lipid-protein interface and caused drastic changes in the lipid interactions. The simulation results show that lipid interactions to the human Na+,K+-ATPase α1β1FXYD protein in the plasma membrane are highly state-dependent and can be disturbed by disease mutations located in the lipid interface, which can open up for new venues to understand genetic disorders.
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Affiliation(s)
- Dhani Ram Mahato
- Department of Chemistry, Umeå University, Umeå, Sweden; Institut de Química Computacional i Catàlisi, Universitat de Girona, Girona, 17003, Spain
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12
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Stachowicz-Kuśnierz A, Korchowiec B, Korchowiec J. Nucleoside Analog Reverse-Transcriptase Inhibitors in Membrane Environment: Molecular Dynamics Simulations. Molecules 2023; 28:6273. [PMID: 37687102 PMCID: PMC10488468 DOI: 10.3390/molecules28176273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 08/15/2023] [Accepted: 08/23/2023] [Indexed: 09/10/2023] Open
Abstract
The behavior of four drugs from the family of nucleoside analog reverse-transcriptase inhibitors (zalcitabine, stavudine, didanosine, and apricitabine) in a membrane environment was traced using molecular dynamics simulations. The simulation models included bilayers and monolayers composed of POPC and POPG phospholipids. It was demonstrated that the drugs have a higher affinity towards POPG membranes than POPC membranes due to attractive long-range electrostatic interactions. The results obtained for monolayers were consistent with those obtained for bilayers. The drugs accumulated in the phospholipid polar headgroup region. Two adsorption modes were distinguished. They differed in the degree of penetration of the hydrophilic headgroup region. Hydrogen bonds between drug molecules and phospholipid heads were responsible for adsorption. It was shown that apricitabine penetrated the hydrophilic part of the POPC and POPG membranes more effectively than the other drugs. Van der Waals interactions between S atoms and lipids were responsible for this.
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Affiliation(s)
| | | | - Jacek Korchowiec
- Faculty of Chemistry, Jagiellonian University, Gronostajowa 2, 30-387 Krakow, Poland; (A.S.-K.); (B.K.)
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13
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Sahrmann P, Loose TD, Durumeric AEP, Voth GA. Utilizing Machine Learning to Greatly Expand the Range and Accuracy of Bottom-Up Coarse-Grained Models through Virtual Particles. J Chem Theory Comput 2023; 19:4402-4413. [PMID: 36802592 PMCID: PMC10373655 DOI: 10.1021/acs.jctc.2c01183] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Indexed: 02/22/2023]
Abstract
Coarse-grained (CG) models parametrized using atomistic reference data, i.e., "bottom up" CG models, have proven useful in the study of biomolecules and other soft matter. However, the construction of highly accurate, low resolution CG models of biomolecules remains challenging. We demonstrate in this work how virtual particles, CG sites with no atomistic correspondence, can be incorporated into CG models within the context of relative entropy minimization (REM) as latent variables. The methodology presented, variational derivative relative entropy minimization (VD-REM), enables optimization of virtual particle interactions through a gradient descent algorithm aided by machine learning. We apply this methodology to the challenging case of a solvent-free CG model of a 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) lipid bilayer and demonstrate that introduction of virtual particles captures solvent-mediated behavior and higher-order correlations which REM alone cannot capture in a more standard CG model based only on the mapping of collections of atoms to the CG sites.
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Affiliation(s)
- Patrick
G. Sahrmann
- Department of Chemistry, Chicago Center
for Theoretical Chemistry, James Franck Institute, and Institute for
Biophysical Dynamics, The University of
Chicago, Chicago, Illinois 60637, United
States
| | - Timothy D. Loose
- Department of Chemistry, Chicago Center
for Theoretical Chemistry, James Franck Institute, and Institute for
Biophysical Dynamics, The University of
Chicago, Chicago, Illinois 60637, United
States
| | - Aleksander E. P. Durumeric
- Department of Chemistry, Chicago Center
for Theoretical Chemistry, James Franck Institute, and Institute for
Biophysical Dynamics, The University of
Chicago, Chicago, Illinois 60637, United
States
| | - Gregory A. Voth
- Department of Chemistry, Chicago Center
for Theoretical Chemistry, James Franck Institute, and Institute for
Biophysical Dynamics, The University of
Chicago, Chicago, Illinois 60637, United
States
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14
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Kav B, Weikl TR, Schneck E. Measuring pico-Newton Forces with Lipid Anchors as Force Sensors in Molecular Dynamics Simulations. J Phys Chem B 2023; 127:4081-4089. [PMID: 37127845 PMCID: PMC10184124 DOI: 10.1021/acs.jpcb.3c00063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Binding forces between biomolecules are ubiquitous in nature but sometimes as weak as a few pico-Newtons (pN). In many cases, the binding partners are attached to biomembranes with the help of a lipid anchor. One important example are glycolipids that promote membrane adhesion through weak carbohydrate-carbohydrate binding between adjacent membranes. Here, we use molecular dynamics (MD) simulations to quantify the forces generated by bonds involving membrane-anchored molecules. We introduce a method in which the protrusion of the lipid anchors from the membrane acts as the force sensor. Our results with two different glycolipids reveal binding forces of up to 20 pN and corroborate the recent notion that carbohydrate-carbohydrate interactions are generic rather than specific.
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Affiliation(s)
- Batuhan Kav
- Max Planck Institute of Colloids and Interfaces, 14467, Potsdam, Germany
- Institute of Biological Information Processing: Structural Biochemistry (IBI-7), Forschungszentrum Jülich, 52428 Jülich, Germany
| | - Thomas R Weikl
- Max Planck Institute of Colloids and Interfaces, 14467, Potsdam, Germany
| | - Emanuel Schneck
- Max Planck Institute of Colloids and Interfaces, 14467, Potsdam, Germany
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, 64289 Darmstadt, Germany
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15
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Ho TH, Nguyen TT, Huynh LK. Formation of lipid raft nanodomains in homogeneous ternary lipid mixture of POPC/DPSM/cholesterol: Theoretical insights. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:184027. [PMID: 35995208 DOI: 10.1016/j.bbamem.2022.184027] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 07/16/2022] [Accepted: 08/04/2022] [Indexed: 06/15/2023]
Abstract
Lipid rafts, in biological membranes, are cholesterol-rich nanodomains that regulate many protein activities and cellular processes. Understanding the formation of the lipid-raft nanodomains helps us elucidate many complex interactions in the cell. In this study, the formation of lipid-raft nanodomains in a ternary palmitoyl-oleoyl-phosphatidylcholine/stearoyl-sphingomyelin/cholesterol (POPC/DPSM/Chol) lipid mixture, the most realistic surrogate model for biological membranes, has been successfully observed for the first time in-silico using microsecond timescale molecular dynamics simulations. The model reveals the formation of cholesterol-induced nanodomains with raft-like characteristics and their underlying mechanism: the cholesterol molecules segregate themselves into cholesterol nanodomains and then enrich the cholesterol-rich domain with sphingomyelin molecules to form a lipid raft thanks to the weak bonding of cholesterol with sphingomyelin. Besides, it is found that the increase in cholesterol concentration enhances the biophysical properties (e.g., bilayer thickness, area per lipid headgroup, and order parameter) of the lipid raft nanodomains. Such findings suggest that the POPC/DPSM/Chol bilayer is a suitable model to fundamentally extend the nanodomain evolution to investigate their lifetime and kinetics as well as to study protein-lipid interaction, protein-protein interaction, and selection of therapeutic molecules in the presence of lipid rafts.
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Affiliation(s)
- Tho H Ho
- Vietnam National University, Ho Chi Minh, Vietnam; Chemical Engineering Department, School of Biotechnology, International University, Quarter 6, Linh Trung Ward, Thu Duc City, Ho Chi Minh City 700000, Vietnam
| | - Trang T Nguyen
- Vietnam National University, Ho Chi Minh, Vietnam; Chemical Engineering Department, School of Biotechnology, International University, Quarter 6, Linh Trung Ward, Thu Duc City, Ho Chi Minh City 700000, Vietnam.
| | - Lam K Huynh
- Vietnam National University, Ho Chi Minh, Vietnam; Chemical Engineering Department, School of Biotechnology, International University, Quarter 6, Linh Trung Ward, Thu Duc City, Ho Chi Minh City 700000, Vietnam.
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16
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Abbas G, Cardenas AE, Elber R. The Structures of Heterogeneous Membranes and Their Interactions with an Anticancer Peptide: A Molecular Dynamics Study. Life (Basel) 2022; 12:1473. [PMID: 36294908 PMCID: PMC9604715 DOI: 10.3390/life12101473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/16/2022] [Accepted: 09/20/2022] [Indexed: 12/02/2022] Open
Abstract
We conduct molecular dynamics simulations of model heterogeneous membranes and their interactions with a 24-amino acid peptide-NAF-144-67. NAF-144-67 is an anticancer peptide that selectively permeates and kills malignant cells; it does not permeate normal cells. We examine three membranes with different binary mixtures of lipids, DOPC-DOPA, DOPC-DOPS, and DOPC-DOPE, with a single peptide embedded in each as models for the diversity of biological membranes. We illustrate that the peptide organization in the membrane depends on the types of nearby phospholipids and is influenced by the charge and size of the head groups. The present study sheds light on early events of permeation and the mechanisms by which an amphiphilic peptide crosses from an aqueous solution to a hydrophobic membrane. Understanding the translocation mechanism is likely to help the design of new permeants.
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Affiliation(s)
- Ghulam Abbas
- National Center for Bioinformatics, Quaid-i-Azam University, Islamabad 45320, Pakistan or
| | - Alfredo E. Cardenas
- Oden Institute for Computational and Engineering Sciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Ron Elber
- Oden Institute for Computational and Engineering Sciences, University of Texas at Austin, Austin, TX 78712, USA
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, USA
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17
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Nasrollahpour M, Vafaee M, Razzaghi S. Structural and Dynamical Properties of Palmitoyl-Oleoyl Phosphatidylserine Lipid Nanotubes Containing Cholesterols and PEGylated Dioleoyl Phosphatidylethanolamine: A Coarse-Grained Molecular Dynamics Simulation. Chem Eng Sci 2022. [DOI: 10.1016/j.ces.2022.117848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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18
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Nyepetsi M, Mbaiwa F, Oyetunji OA, de Leeuw NH. Understanding the Interactions between Triolein and Cosolvent Binary Mixtures Using Molecular Dynamics Simulations. ACS OMEGA 2022; 7:10212-10224. [PMID: 35382278 PMCID: PMC8973112 DOI: 10.1021/acsomega.1c06762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 03/01/2022] [Indexed: 06/14/2023]
Abstract
Biodiesel is one of the emerging renewable sources of energy to replace fossil-fuel-based resources. It is produced by a transesterification reaction in which a triglyceride reacts with methanol in the presence of a catalyst. The reaction is slow because of the low solubility of methanol in triglycerides, which results in low concentrations of methanol available to react with triglyceride. To speed up the reaction, cosolvents are added to create a single phase which helps to improve the concentration of methanol in the triglyceride phase. In this study, molecular dynamics simulations are used to help understand the role of cosolvents in the solvation of triglyceride (triolein). Six binary mixtures of triolein/cosolvent were used to study the solvation of triolein at 298.15 K. Results of 100 ns simulations at constant temperature and pressure to simulate mixing experiments show that in the first 10 ns all the binary mixtures remain largely unmixed. However, for the cosolvents that are fully miscible with triolein, the partial densities across the simulation boxes show that the systems are fully mixed in the final 10 ns. Some solvents were found to interact strongly with the polar part of triolein, while others interacted with the aliphatic part. The radial distribution functions and clustering of the solvents around triolein were also used as indicators for solvation. The presence of cosolvents also influenced the conformation of triolein molecules. In the presence of solvents that solubilize it, triolein preferred a propeller conformation but took up a trident conformation when there is less or no solubilization. The results show that tetrahydrofuran is the best solvent at solubilizing triolein, followed by cyclopentyl methyl ether, diethyl ether, and hexane. With 1,4-dioxane, the solubility improves with an increase in temperature. The miscibility of a solvent in triolein is aided by its ability to interact with both the polar and nonpolar parts of triolein.
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Affiliation(s)
- Maipelo Nyepetsi
- Department
of Chemical and Forensic Sciences, Botswana
International University of Science and Technology (BIUST), Palapye, Botswana
| | - Foster Mbaiwa
- Department
of Chemical and Forensic Sciences, Botswana
International University of Science and Technology (BIUST), Palapye, Botswana
| | | | - Nora H. de Leeuw
- School
of Chemistry, Cardiff University, Cardiff CF10 3AT, United Kingdom
- School
of Chemistry, University of Leeds, Leeds LS2 9JT, United Kingdom
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19
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Hsieh MK, Yu Y, Klauda JB. All-Atom Modeling of Complex Cellular Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:3-17. [PMID: 34962814 DOI: 10.1021/acs.langmuir.1c02084] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Cell membranes are composed of a variety of lipids and proteins where they interact with each other to fulfill their roles. The first step in modeling these interactions in molecular simulations is to have reliable mimetics of the membrane's lipid environment. This Feature Article presents our recent efforts to model complex cellular membranes using all-atom force fields. A short review of the CHARMM36 (C36) lipid force field and its recent update to incorporate the long-range dispersion is presented. Key examples of model membranes mimicking various species and organelles are given. These include single-celled organisms such as bacteria (E. coli., chlamydia, and P. aeruginosa) and yeast (plasma membrane, endoplasmic reticulum, and trans-Golgi network) and more advanced ones such as plants (soybean and Arabidopsis thaliana) and mammals (ocular lens, stratum corneum, and peripheral nerve myelin). Leaflet asymmetry in composition has also been applied to some of these models. With the increased lipid diversity in the C36 lipid FF, these complex models can better reflect the structural, mechanical, and dynamic properties of realistic membranes and open an opportunity to study biological processes involving other molecules.
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20
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Oliveira MC, Yusupov M, Bogaerts A, Cordeiro RM. Distribution of lipid aldehydes in phase-separated membranes: A molecular dynamics study. Arch Biochem Biophys 2022; 717:109136. [DOI: 10.1016/j.abb.2022.109136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 01/19/2022] [Accepted: 01/21/2022] [Indexed: 11/02/2022]
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21
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Hsieh MK, Klauda JB. Leaflet Asymmetry Modeling in the Lipid Composition of Escherichia coli Cytoplasmic Membranes. J Phys Chem B 2021; 126:184-196. [PMID: 34962410 DOI: 10.1021/acs.jpcb.1c07332] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Lipid composition asymmetry between leaflets is important to cell function and plays a key role in the "positive inside" rule in transmembrane proteins. In this work, Escherichia coli inner plasma membrane models reflecting this asymmetry have been investigated at the early-log and stationary stages during the bacterial lifecycle using all-atom molecular dynamics simulations. The CHARMM36 lipid force field is used, and selected membrane properties are tested for variations between two leaflets and whole membranes. Our models include bacterial lipids with a cyclopropane moiety on the sn-2 acyl chain in the stationary membrane model. The PE/PG ratio for two leaflets reflects the "positive inside" rule of membrane proteins, set to 6.8 and 2.8 for the inner and outer leaflets of the two models, respectively. We are the first to model leaflet asymmetry in the lipid composition of E. coli cytoplasmic membranes and observe the effect on membrane properties in leaflets and whole membranes. Specifically, our results show that for the stationary phase bilayer, the surface area per lipid (SA/lipid) is larger, the thickness (2DC and DB) is smaller, the tilt angle is larger, the tilt modulus is smaller, and the deuterium order parameters (SCD) of sn-1 and sn-2 tails are lower, compared to the early-log stage. Moreover, the stationary stage bilayer has a positive spontaneous curvature, while the early-log stage has a near flat spontaneous curvature. For leaflet asymmetry, the inner leaflet has a larger SA/lipid, a smaller thickness, a smaller elastic tilt modulus (a larger tilt angle), and lower SCD, compared to the outer leaflet in both stages. Moreover, an asymmetric membrane involves a lipid tilt and a lateral extension, varying from a reference state of a pre-equilibrium membrane. This work encourages a more profound exploration of leaflet asymmetry in various other membrane models and how this might affect the structure and function of membrane-associated peptides and proteins.
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Affiliation(s)
- Min-Kang Hsieh
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742, United States
| | - Jeffery B Klauda
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742, United States.,Biophysics Program, University of Maryland, College Park, Maryland 20742, United States
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22
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Róg T, Girych M, Bunker A. Mechanistic Understanding from Molecular Dynamics in Pharmaceutical Research 2: Lipid Membrane in Drug Design. Pharmaceuticals (Basel) 2021; 14:1062. [PMID: 34681286 PMCID: PMC8537670 DOI: 10.3390/ph14101062] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 11/17/2022] Open
Abstract
We review the use of molecular dynamics (MD) simulation as a drug design tool in the context of the role that the lipid membrane can play in drug action, i.e., the interaction between candidate drug molecules and lipid membranes. In the standard "lock and key" paradigm, only the interaction between the drug and a specific active site of a specific protein is considered; the environment in which the drug acts is, from a biophysical perspective, far more complex than this. The possible mechanisms though which a drug can be designed to tinker with physiological processes are significantly broader than merely fitting to a single active site of a single protein. In this paper, we focus on the role of the lipid membrane, arguably the most important element outside the proteins themselves, as a case study. We discuss work that has been carried out, using MD simulation, concerning the transfection of drugs through membranes that act as biological barriers in the path of the drugs, the behavior of drug molecules within membranes, how their collective behavior can affect the structure and properties of the membrane and, finally, the role lipid membranes, to which the vast majority of drug target proteins are associated, can play in mediating the interaction between drug and target protein. This review paper is the second in a two-part series covering MD simulation as a tool in pharmaceutical research; both are designed as pedagogical review papers aimed at both pharmaceutical scientists interested in exploring how the tool of MD simulation can be applied to their research and computational scientists interested in exploring the possibility of a pharmaceutical context for their research.
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Affiliation(s)
- Tomasz Róg
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland;
| | - Mykhailo Girych
- Department of Physics, University of Helsinki, 00014 Helsinki, Finland;
| | - Alex Bunker
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, 00014 Helsinki, Finland;
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23
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Nele V, Holme MN, Rashid MH, Barriga HMG, Le TC, Thomas MR, Doutch JJ, Yarovsky I, Stevens MM. Design of Lipid-Based Nanocarriers via Cation Modulation of Ethanol-Interdigitated Lipid Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:11909-11921. [PMID: 34581180 DOI: 10.1021/acs.langmuir.1c02076] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Short-chain alcohols (i.e., ethanol) can induce membrane interdigitation in saturated-chain phosphatidylcholines (PCs). In this process, alcohol molecules intercalate between phosphate heads, increasing lateral separation and favoring hydrophobic interactions between opposing acyl chains, which interpenetrate forming an interdigitated phase. Unraveling mechanisms underlying the interactions between ethanol and model lipid membranes has implications for cell biology, biochemistry, and for the formulation of lipid-based nanocarriers. However, investigations of ethanol-lipid membrane systems have been carried out in deionized water, which limits their applicability. Here, using a combination of small- and wide-angle X-ray scattering, small-angle neutron scattering, and all-atom molecular dynamics simulations, we analyzed the effect of varying CaCl2 and NaCl concentrations on ethanol-induced interdigitation. We observed that while ethanol addition leads to the interdigitation of bulk phase 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers in the presence of CaCl2 and NaCl regardless of the salt concentration, the ethanol-induced interdigitation of vesicular DPPC depends on the choice of cation and its concentration. These findings unravel a key role for cations in the ethanol-induced interdigitation of lipid membranes in either bulk phase or vesicular form.
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Affiliation(s)
- Valeria Nele
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, U.K
| | - Margaret N Holme
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, U.K
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - M Harunur Rashid
- School of Engineering, RMIT University, Melbourne, Victoria 3001, Australia
- Department of Mathematics and Physics, North South University, Bashundhara, Dhaka 1229, Bangladesh
| | - Hanna M G Barriga
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
| | - Tu C Le
- School of Engineering, RMIT University, Melbourne, Victoria 3001, Australia
| | - Michael R Thomas
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, U.K
- London Centre for Nanotechnology and Department of Biochemical Engineering, University College London, 17-19 Gordon Street, London WC1H 0AH, U.K
| | - James J Doutch
- ISIS Neutron and Muon Source, STFC, Rutherford Appleton Laboratory, Didcot OX11 ODE, U.K
| | - Irene Yarovsky
- School of Engineering, RMIT University, Melbourne, Victoria 3001, Australia
| | - Molly M Stevens
- Department of Materials, Department of Bioengineering and Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, U.K
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, SE-171 77 Stockholm, Sweden
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24
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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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25
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Glielmo A, Husic BE, Rodriguez A, Clementi C, Noé F, Laio A. Unsupervised Learning Methods for Molecular Simulation Data. Chem Rev 2021; 121:9722-9758. [PMID: 33945269 PMCID: PMC8391792 DOI: 10.1021/acs.chemrev.0c01195] [Citation(s) in RCA: 116] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Indexed: 12/21/2022]
Abstract
Unsupervised learning is becoming an essential tool to analyze the increasingly large amounts of data produced by atomistic and molecular simulations, in material science, solid state physics, biophysics, and biochemistry. In this Review, we provide a comprehensive overview of the methods of unsupervised learning that have been most commonly used to investigate simulation data and indicate likely directions for further developments in the field. In particular, we discuss feature representation of molecular systems and present state-of-the-art algorithms of dimensionality reduction, density estimation, and clustering, and kinetic models. We divide our discussion into self-contained sections, each discussing a specific method. In each section, we briefly touch upon the mathematical and algorithmic foundations of the method, highlight its strengths and limitations, and describe the specific ways in which it has been used-or can be used-to analyze molecular simulation data.
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Affiliation(s)
- Aldo Glielmo
- International
School for Advanced Studies (SISSA) 34014 Trieste, Italy
| | - Brooke E. Husic
- Freie
Universität Berlin, Department of Mathematics
and Computer Science, 14195 Berlin, Germany
| | - Alex Rodriguez
- International Centre for Theoretical
Physics (ICTP), Condensed Matter and Statistical
Physics Section, 34100 Trieste, Italy
| | - Cecilia Clementi
- Freie
Universität Berlin, Department for
Physics, 14195 Berlin, Germany
- Rice
University Houston, Department of Chemistry, Houston, Texas 77005, United States
| | - Frank Noé
- Freie
Universität Berlin, Department of Mathematics
and Computer Science, 14195 Berlin, Germany
- Freie
Universität Berlin, Department for
Physics, 14195 Berlin, Germany
- Rice
University Houston, Department of Chemistry, Houston, Texas 77005, United States
| | - Alessandro Laio
- International
School for Advanced Studies (SISSA) 34014 Trieste, Italy
- International Centre for Theoretical
Physics (ICTP), Condensed Matter and Statistical
Physics Section, 34100 Trieste, Italy
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26
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Gutiérrez-Chávez C, Benaud N, Ferrari BC. The ecological roles of microbial lipopeptides: Where are we going? Comput Struct Biotechnol J 2021; 19:1400-1413. [PMID: 33777336 PMCID: PMC7960500 DOI: 10.1016/j.csbj.2021.02.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 02/18/2021] [Accepted: 02/20/2021] [Indexed: 12/30/2022] Open
Abstract
Lipopeptides (LPs) are secondary metabolites produced by a diversity of bacteria and fungi. Their unique chemical structure comprises both a peptide and a lipid moiety. LPs are of major biotechnological interest owing to their emulsification, antitumor, immunomodulatory, and antimicrobial activities. To date, these versatile compounds have been applied across multiple industries, from pharmaceuticals through to food processing, cosmetics, agriculture, heavy metal, and hydrocarbon bioremediation. The variety of LP structures and the diversity of the environments from which LP-producing microorganisms have been isolated suggest important functions in their natural environment. However, our understanding of the ecological role of LPs is limited. In this review, the mode of action and the role of LPs in motility, antimicrobial activity, heavy metals removal and biofilm formation are addressed. We include discussion on the need to characterise LPs from a diversity of microorganisms, with a focus on taxa inhabiting 'extreme' environments. We introduce the use of computational target fishing and molecular dynamics simulations as powerful tools to investigate the process of interaction between LPs and cell membranes. Together, these advances will provide new understanding of the mechanism of action of novel LPs, providing greater insights into the roles of LPs in the natural environment.
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Affiliation(s)
| | - Nicole Benaud
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney 2052, Australia
| | - Belinda C Ferrari
- School of Biotechnology and Biomolecular Sciences, UNSW Sydney 2052, Australia
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27
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Wadhwa R, Yadav NS, Katiyar SP, Yaguchi T, Lee C, Ahn H, Yun CO, Kaul SC, Sundar D. Molecular dynamics simulations and experimental studies reveal differential permeability of withaferin-A and withanone across the model cell membrane. Sci Rep 2021; 11:2352. [PMID: 33504873 PMCID: PMC7840742 DOI: 10.1038/s41598-021-81729-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 12/30/2020] [Indexed: 12/23/2022] Open
Abstract
Poor bioavailability due to the inability to cross the cell membrane is one of the major reasons for the failure of a drug in clinical trials. We have used molecular dynamics simulations to predict the membrane permeability of natural drugs-withanolides (withaferin-A and withanone) that have similar structures but remarkably differ in their cytotoxicity. We found that whereas withaferin-A, could proficiently transverse through the model membrane, withanone showed weak permeability. The free energy profiles for the interaction of withanolides with the model bilayer membrane revealed that whereas the polar head group of the membrane caused high resistance for the passage of withanone, the interior of the membrane behaves similarly for both withanolides. The solvation analysis further revealed that the high solvation of terminal O5 oxygen of withaferin-A was the major driving force for its high permeability; it interacted with the phosphate group of the membrane that led to its smooth passage across the bilayer. The computational predictions were tested by raising and recruiting unique antibodies that react to withaferin-A and withanone. The time-lapsed analyses of control and treated cells demonstrated higher permeation of withaferin-A as compared to withanone. The concurrence between the computation and experimental results thus re-emphasised the use of computational methods for predicting permeability and hence bioavailability of natural drug compounds in the drug development process.
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Affiliation(s)
- Renu Wadhwa
- AIST-INDIA DAILAB, DBT-AIST International Center for Translational and Environmental Research (DAICENTER), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305 8565, Japan
| | - Neetu Singh Yadav
- DAILAB, Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi, 110 016, India
| | - Shashank P Katiyar
- DAILAB, Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi, 110 016, India
| | - Tomoko Yaguchi
- AIST-INDIA DAILAB, DBT-AIST International Center for Translational and Environmental Research (DAICENTER), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305 8565, Japan
| | - Chohee Lee
- AIST-INDIA DAILAB, DBT-AIST International Center for Translational and Environmental Research (DAICENTER), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305 8565, Japan.,Department of Bioengineering, College of Engineering, Hanyang University, 222 Wangsinmi-ro, Seongdong-gu, Seoul, 04763, Republic of Korea
| | - Hyomin Ahn
- AIST-INDIA DAILAB, DBT-AIST International Center for Translational and Environmental Research (DAICENTER), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305 8565, Japan.,Department of Bioengineering, College of Engineering, Hanyang University, 222 Wangsinmi-ro, Seongdong-gu, Seoul, 04763, Republic of Korea.,GeneMedicine Co., Ltd, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Republic of Korea
| | - Chae-Ok Yun
- Department of Bioengineering, College of Engineering, Hanyang University, 222 Wangsinmi-ro, Seongdong-gu, Seoul, 04763, Republic of Korea.,GeneMedicine Co., Ltd, 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Republic of Korea.,Institute of Nano Science and Technology (INST), 222 Wangsimni-ro, Seongdong-gu, Seoul, 04763, Republic of Korea
| | - Sunil C Kaul
- AIST-INDIA DAILAB, DBT-AIST International Center for Translational and Environmental Research (DAICENTER), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305 8565, Japan.
| | - Durai Sundar
- DAILAB, Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology (IIT) Delhi, Hauz Khas, New Delhi, 110 016, India.
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28
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Yang J, Jin J, Li S. Role of polyunsaturated phospholipids in liquid-ordered and liquid-disordered phases. RSC Adv 2021; 11:27115-27120. [PMID: 35480686 PMCID: PMC9037819 DOI: 10.1039/d1ra02692e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Accepted: 07/30/2021] [Indexed: 11/21/2022] Open
Abstract
Polyunsaturated phospholipids play a strong repulsive role in the liquid-disordered phase but a weak role in the liquid-ordered phase.
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Affiliation(s)
- Jing Yang
- College of Education, Wenzhou University, Wenzhou, Zhejiang 325035, China
| | - Jianyu Jin
- College of Education, Wenzhou University, Wenzhou, Zhejiang 325035, China
| | - Shiben Li
- Department of Physics, Wenzhou University, Wenzhou, Zhejiang 325035, China
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29
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Krämer A, Ghysels A, Wang E, Venable RM, Klauda JB, Brooks BR, Pastor RW. Membrane permeability of small molecules from unbiased molecular dynamics simulations. J Chem Phys 2020; 153:124107. [PMID: 33003739 PMCID: PMC7519415 DOI: 10.1063/5.0013429] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 08/31/2020] [Indexed: 12/26/2022] Open
Abstract
Permeation of many small molecules through lipid bilayers can be directly observed in molecular dynamics simulations on the nano- and microsecond timescale. While unbiased simulations provide an unobstructed view of the permeation process, their feasibility for computing permeability coefficients depends on various factors that differ for each permeant. The present work studies three small molecules for which unbiased simulations of permeation are feasible within less than a microsecond, one hydrophobic (oxygen), one hydrophilic (water), and one amphiphilic (ethanol). Permeabilities are computed using two approaches: counting methods and a maximum-likelihood estimation for the inhomogeneous solubility diffusion (ISD) model. Counting methods yield nearly model-free estimates of the permeability for all three permeants. While the ISD-based approach is reasonable for oxygen, it lacks precision for water due to insufficient sampling and results in misleading estimates for ethanol due to invalid model assumptions. It is also demonstrated that simulations using a Langevin thermostat with collision frequencies of 1/ps and 5/ps yield oxygen permeabilities and diffusion constants that are lower than those using Nosé-Hoover by statistically significant margins. In contrast, permeabilities from trajectories generated with Nosé-Hoover and the microcanonical ensemble do not show statistically significant differences. As molecular simulations become more affordable and accurate, calculation of permeability for an expanding range of molecules will be feasible using unbiased simulations. The present work summarizes theoretical underpinnings, identifies pitfalls, and develops best practices for such simulations.
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Affiliation(s)
- Andreas Krämer
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - An Ghysels
- IBiTech - BioMMeda, Ghent University, Corneel Heymanslaan 10, Block B - Entrance 36, 9000 Gent, Belgium
| | - Eric Wang
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20740, USA
| | - Richard M. Venable
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jeffery B. Klauda
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20740, USA
| | - Bernard R. Brooks
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Richard W. Pastor
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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30
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Olżyńska A, Kulig W, Mikkolainen H, Czerniak T, Jurkiewicz P, Cwiklik L, Rog T, Hof M, Jungwirth P, Vattulainen I. Tail-Oxidized Cholesterol Enhances Membrane Permeability for Small Solutes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:10438-10447. [PMID: 32804507 PMCID: PMC7482392 DOI: 10.1021/acs.langmuir.0c01590] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/16/2020] [Indexed: 06/01/2023]
Abstract
Cholesterol renders mammalian cell membranes more compact by reducing the amount of voids in the membrane structure. Because of this, cholesterol is known to regulate the ability of cell membranes to prevent the permeation of water and water-soluble molecules through the membranes. Meanwhile, it is also known that even seemingly tiny modifications in the chemical structure of cholesterol can lead to notable changes in membrane properties. The question is, how significantly do these small changes in cholesterol structure affect the permeability barrier function of cell membranes? In this work, we applied fluorescence methods as well as atomistic molecular dynamics simulations to characterize changes in lipid membrane permeability induced by cholesterol oxidation. The studied 7β-hydroxycholesterol (7β-OH-chol) and 27-hydroxycholesterol (27-OH-chol) represent two distinct groups of oxysterols, namely, ring- and tail-oxidized cholesterols, respectively. Our previous research showed that the oxidation of the cholesterol tail has only a marginal effect on the structure of a lipid bilayer; however, oxidation was found to disturb membrane dynamics by introducing a mechanism that allows sterol molecules to move rapidly back and forth across the membrane-bobbing. Herein, we show that bobbing of 27-OH-chol accelerates fluorescence quenching of NBD-lipid probes in the inner leaflet of liposomes by dithionite added to the liposomal suspension. Systematic experiments using fluorescence quenching spectroscopy and microscopy led to the conclusion that the presence of 27-OH-chol increases membrane permeability to the dithionite anion. Atomistic molecular dynamics simulations demonstrated that 27-OH-chol also facilitates water transport across the membrane. The results support the view that oxysterol bobbing gives rise to successive perturbations to the hydrophobic core of the membrane, and these perturbations promote the permeation of water and small water-soluble molecules through a lipid bilayer. The observed impairment of permeability can have important consequences for eukaryotic organisms. The effects described for 27-OH-chol were not observed for 7β-OH-chol which represents ring-oxidized sterols.
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Affiliation(s)
- Agnieszka Olżyńska
- J.
Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - Waldemar Kulig
- Department
of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Heikki Mikkolainen
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Tomasz Czerniak
- Faculty
of Biotechnology, University of Wrocław, Joliot-Curie 14A, 50-383 Wrocław, Poland
| | - Piotr Jurkiewicz
- J.
Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - Lukasz Cwiklik
- J.
Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - Tomasz Rog
- Department
of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Martin Hof
- J.
Heyrovský Institute of Physical Chemistry, Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - Pavel Jungwirth
- Institute
of Organic Chemistry and Biochemistry, Czech
Academy of Sciences, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
| | - Ilpo Vattulainen
- Department
of Physics, University of Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
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31
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Zou G, Liu Y, Gao H. EML webinar overview: Simulation-assisted discovery of membrane targeting nanomedicine. EXTREME MECHANICS LETTERS 2020; 39:100817. [PMID: 32537481 PMCID: PMC7278653 DOI: 10.1016/j.eml.2020.100817] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 06/05/2020] [Indexed: 05/05/2023]
Abstract
The COVID-19 pandemic has brought infectious diseases again to the forefront of global public health concerns. In this EML webinar (Gao, 2020), we discuss some recent work on simulation-assisted discovery of membrane targeting nanomedicine to counter increasing antimicrobial resistance and potential application of similar ideas to the current pandemic. A recent report led by the world health organization (WHO) warned that 10 million people worldwide could die of bacterial infections each year by 2050. To avert the crisis, membrane targeting antibiotics are drawing increasing attention due to their intrinsic advantage of low resistance development. In collaboration with a number of experimental groups, we show examples of simulation-assisted discovery of molecular agents capable of selectively penetrating and aggregating in bacterial lipid membranes, causing membrane permeability/rupture. Through systematic all-atom molecular dynamics simulations and free energy analysis, we demonstrate that the membrane activity of the molecular agents correlates with their ability to enter, perturb and permeabilize the lipid bilayers. Further study on different cell membranes demonstrates that the selectivity results from the presence of cholesterol in mammalian but not in bacterial membranes, as the cholesterol can condense the hydrophobic region of membrane, preventing the penetration of the molecular agents. Following the molecular penetration, we establish a continuum theory and derive the energetic driving force for the domain aggregation and pore growth on lipid membrane. We show that the energy barrier to membrane pore formation can be significantly lowered through molecular aggregation on a large domain with intrinsic curvature and a sharp interface. The theory is consistent with experimental observations and validated with coarse-grained molecular dynamics simulations of molecular domain aggregation leading to pore formation in a lipid membrane. The mechanistic modelling and simulation provide some fundamental principles on how molecular antimicrobials interact with bacterial membranes and damage them through domain aggregation and pore formation. For treating viral infections and cancer therapy, we discuss potential size- and lipid-type-based selectivity principles for developing membrane active nanomedicine. These studies suggest a general simulation-assisted platform to accelerate discovery and innovation in nanomedicine against infectious diseases. EML Webinar speakers are updated at https://imechanica.org/node/24132.
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Affiliation(s)
- Guijin Zou
- Institute of High Performance Computing, A*STAR, Singapore 138632, Singapore
| | - Yue Liu
- School of Engineering, Brown University, Providence, RI 02912, USA
| | - Huajian Gao
- Institute of High Performance Computing, A*STAR, Singapore 138632, Singapore
- School of Engineering, Brown University, Providence, RI 02912, USA
- School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, 70 Nanyang Drive, Singapore 639798, Singapore
- Corresponding author.
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32
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Akutsu H. Structure and dynamics of phospholipids in membranes elucidated by combined use of NMR and vibrational spectroscopies. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183352. [DOI: 10.1016/j.bbamem.2020.183352] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 12/17/2022]
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33
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Kim H, Lee BH, Choi MK, Seo S, Kim MK. Effects of aquaporin-lipid molar ratio on the permeability of an aquaporin Z-phospholipid membrane system. PLoS One 2020; 15:e0237789. [PMID: 32810188 PMCID: PMC7437467 DOI: 10.1371/journal.pone.0237789] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 08/02/2020] [Indexed: 11/22/2022] Open
Abstract
Aquaporins are water-permeable membrane-channel proteins found in biological cell membranes that selectively exclude ions and large molecules and have high water permeability, which makes them promising candidates for water desalination systems. To effectively apply the properties of aquaporins in the desalination process, many studies have been conducted on aquaporin-lipid membrane systems using phospholipids, which are the main component of cell membranes. Many parametric studies have evaluated the permeability of such systems with various aquaporin types and lipid compositions. In this study, we performed molecular dynamics simulations for four cases with different protein-lipid molar ratios (1:50, 1:75, 1:100, and 1:150) between aquaporin Z and the phospholipids, and we propose a possibility of the existence of optimal protein-lipid molar ratio to maximize water permeability. Elucidating these simulation results from a structural viewpoint suggests that there is a relationship between the permeability and changes in the hydrophobic thickness of the lipid membrane adjacent to the aquaporin as a structural parameter. The results of this study can help optimize the design of an aquaporin-lipid membrane by considering its molar ratio at an early stage of development.
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Affiliation(s)
- Hyunki Kim
- School of Mechanical Engineering, Sungkyunkwan University, Suwon, Republic of Korea
| | - Byung Ho Lee
- School of Mechanical Engineering, Sungkyunkwan University, Suwon, Republic of Korea
| | - Moon-ki Choi
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN, United States of America
| | - Sangjae Seo
- Korean Institute of Science and Technology Information, Daejeon, Republic of Korea
| | - Moon Ki Kim
- School of Mechanical Engineering, Sungkyunkwan University, Suwon, Republic of Korea
- * E-mail:
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34
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Sharma P, Parthasarathi S, Patil N, Waskar M, Raut JS, Puranik M, Ayappa KG, Basu JK. Assessing Barriers for Antimicrobial Penetration in Complex Asymmetric Bacterial Membranes: A Case Study with Thymol. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:8800-8814. [PMID: 32609530 DOI: 10.1021/acs.langmuir.0c01124] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The bacterial cell envelope is a complex multilayered structure evolved to protect bacteria in hostile environments. An understanding of the molecular basis for the interaction and transport of antibacterial therapeutics with the bacterial cell envelope will enable the development of drug molecules to combat bacterial infections and suppress the emergence of drug-resistant strains. Here we report the successful creation of an in vitro supported lipid bilayer (SLB) platform of the outer membrane (OM) of E. coli, an archetypical Gram-negative bacterium, containing the full smooth lipopolysaccharide (S-LPS) architecture of the membrane. Using this platform, we performed fluorescence correlation spectroscopy (FCS) in combination with molecular dynamics (MD) simulations to measure lipid diffusivities and provide molecular insights into the transport of natural antimicrobial agent thymol. Lipid diffusivities measured on symmetric supported lipid bilayers made up of inner membrane lipids show a distinct increase in the presence of thymol as also corroborated by MD simulations. However, lipid diffusivities in the asymmetric OM consisting of only S-LPS are invariant upon exposure to thymol. Increasing the phospholipid content in the LPS-containing outer leaflet improved the penetration toward thymol as reflected in slightly higher relative diffusivity changes in the inner leaflet when compared with the outer leaflet. Free-energy computations reveal the presence of a barrier (∼6 kT) only in the core-saccharide region of the OM for the translocation of thymol while the external O-antigen part is easily traversed. In contrast, thymol spontaneously inserts into the inner membrane. In addition to providing leaflet-resolved penetration barriers in bacterial membranes, we also assess the ability of small molecules to penetrate various membrane components. With rising bacterial resistance, our study opens up the possibility of screening potential antimicrobial drug candidates using these realistic model platforms for Gram-negative bacteria.
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Affiliation(s)
| | | | - Nivedita Patil
- Unilever RD Bangalore, 64 Main Road, Whitefield, Bangalore 560066, India
| | - Morris Waskar
- Unilever RD Bangalore, 64 Main Road, Whitefield, Bangalore 560066, India
| | - Janhavi S Raut
- Unilever RD Bangalore, 64 Main Road, Whitefield, Bangalore 560066, India
| | - Mrinalini Puranik
- Unilever RD Bangalore, 64 Main Road, Whitefield, Bangalore 560066, India
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The Neutrally Charged Diarylurea Compound PQ401 Kills Antibiotic-Resistant and Antibiotic-Tolerant Staphylococcus aureus. mBio 2020; 11:mBio.01140-20. [PMID: 32605985 PMCID: PMC7327171 DOI: 10.1128/mbio.01140-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Membrane-damaging antimicrobial agents have great potential to treat multidrug-resistant or multidrug-tolerant bacteria against which conventional antibiotics are not effective. However, their therapeutic applications are often hampered due to their low selectivity to bacterial over mammalian membranes or their potential for cross-resistance to a broad spectrum of cationic membrane-active antimicrobial agents. We discovered that the diarylurea derivative compound PQ401 has antimicrobial potency against multidrug-resistant and multidrug-tolerant Staphylococcus aureus. PQ401 selectively disrupts bacterial membrane lipid bilayers in comparison to mammalian membranes. Unlike cationic membrane-active antimicrobials, the neutral form of PQ401 rather than its cationic form exhibits maximum membrane activity. Overall, our results demonstrate that PQ401 could be a promising lead compound that overcomes the current limitations of membrane selectivity and cross-resistance. Also, this work provides deeper insight into the design and development of new noncharged membrane-targeting therapeutics to combat hard-to-cure bacterial infections. Resistance or tolerance to traditional antibiotics is a challenging issue in antimicrobial chemotherapy. Moreover, traditional bactericidal antibiotics kill only actively growing bacterial cells, whereas nongrowing metabolically inactive cells are tolerant to and therefore “persist” in the presence of legacy antibiotics. Here, we report that the diarylurea derivative PQ401, previously characterized as an inhibitor of the insulin-like growth factor I receptor, kills both antibiotic-resistant and nongrowing antibiotic-tolerant methicillin-resistant Staphylococcus aureus (MRSA) by lipid bilayer disruption. PQ401 showed several beneficial properties as an antimicrobial lead compound, including rapid killing kinetics, low probability for resistance development, high selectivity to bacterial membranes compared to mammalian membranes, and synergism with gentamicin. In contrast to well-studied membrane-disrupting cationic antimicrobial low-molecular-weight compounds and peptides, molecular dynamic simulations supported by efficacy data demonstrate that the neutral form of PQ401 penetrates and subsequently embeds into bacterial lipid bilayers more effectively than the cationic form. Lastly, PQ401 showed efficacy in both the Caenorhabditis elegans and Galleria mellonella models of MRSA infection. These data suggest that PQ401 may be a lead candidate for repurposing as a membrane-active antimicrobial and has potential for further development as a human antibacterial therapeutic for difficult-to-treat infections caused by both drug-resistant and -tolerant S. aureus.
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36
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Mostofian B, Johnson QR, Smith JC, Cheng X. Carotenoids promote lateral packing and condensation of lipid membranes. Phys Chem Chem Phys 2020; 22:12281-12293. [PMID: 32432296 DOI: 10.1039/d0cp01031f] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Carotenoids are pigment molecules that protect biomembranes against degradation and may be involved in the formation of functional bacterial membrane microdomains. Little is known on whether different types of carotenoids have different effects on the membrane or if there is any concentration dependence of these effects. In this work, we present results from molecular dynamics simulations of phospholipid bilayers containing different amounts of either β-carotene or zeaxanthin. Both β-carotene and zeaxanthin show the ability to laterally condense the membrane lipids and reduce their inter-leaflet interactions. With increasing concentrations, both carotenoids increase the bilayer thickness and rigidity. The results reveal that carotenoids have similar effects to cholesterol on regulating the behavior of fluid-phase membranes, suggesting that they could function as sterol substitutes and confirming their potential role in the formation of functional membrane domains.
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Affiliation(s)
- Barmak Mostofian
- Center for Molecular Biophysics, Oak Ridge National Lab, Oak Ridge, TN 37830, USA.
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37
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Bradley RP, Slochower DR, Janmey PA, Radhakrishnan R. Divalent cations bind to phosphoinositides to induce ion and isomer specific propensities for nano-cluster initiation in bilayer membranes. ROYAL SOCIETY OPEN SCIENCE 2020; 7:192208. [PMID: 32537210 PMCID: PMC7277276 DOI: 10.1098/rsos.192208] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 04/14/2020] [Indexed: 05/22/2023]
Abstract
We report all-atom molecular dynamics simulations of asymmetric bilayers containing phosphoinositides in the presence of monovalent and divalent cations. We have characterized the molecular mechanism by which these divalent cations interact with phosphoinositides. Ca2+ desolvates more readily, consistent with single-molecule calculations, and forms a network of ionic-like bonds that serve as a 'molecular glue' that allows a single ion to coordinate with up to three phosphatidylinositol-(4,5)-bisphosphate (PI(4, 5)P2) lipids. The phosphatidylinositol-(3,5)-bisphosphate isomer shows no such effect and neither does PI(4, 5)P2 in the presence of Mg2+. The resulting network of Ca2+-mediated lipid-lipid bonds grows to span the entire simulation space and therefore has implications for the lateral distribution of phosophoinositides in the bilayer. We observe context-specific differences in lipid diffusion rates, lipid surface densities and bilayer structure. The molecular-scale delineation of ion-lipid arrangements reported here provides insight into similar nanocluster formation induced by peripheral proteins to regulate the formation of functional signalling complexes on the membrane.
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Affiliation(s)
- Ryan P. Bradley
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - David R. Slochower
- Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Paul A. Janmey
- Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ravi Radhakrishnan
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
- Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
- Author for correspondence: Ravi Radhakrishnan e-mail:
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38
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Hwang H, Hazel A, Lian P, Smith JC, Gumbart JC, Parks JM. A Minimal Membrane Metal Transport System: Dynamics and Energetics of mer Proteins. J Comput Chem 2020; 41:528-537. [PMID: 31721253 PMCID: PMC7263448 DOI: 10.1002/jcc.26098] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 09/17/2019] [Accepted: 10/14/2019] [Indexed: 12/28/2022]
Abstract
The mer operon in bacteria encodes a set of proteins and enzymes that impart resistance to environmental mercury toxicity by importing Hg2+ and reducing it to volatile Hg(0). Because the reduction occurs in the cytoplasm, mercuric ions must first be transported across the cytoplasmic membrane by one of a few known transporters. MerF is the smallest of these, containing only two transmembrane helices and two pairs of vicinal cysteines that coordinate mercuric ions. In this work, we use molecular dynamics simulations to characterize the dynamics of MerF in its apo and Hg2+ -bound states. We find that the apo state positions one of the cysteine pairs closer to the periplasmic side of the membrane, while in the bound state the same pair approaches the cytoplasmic side. This finding is consistent with the functional requirement of accepting Hg2+ from the periplasmic space, sequestering it on acceptance, and transferring it to the cytoplasm. Conformational changes in the TM helices facilitate the functional interaction of the two cysteine pairs. Free-energy calculations provide a barrier of 16 kcal/mol for the association of the periplasmic Hg2+ -bound protein MerP with MerF and 7 kcal/mol for the subsequent association of MerF's two cysteine pairs. Despite the significant conformational changes required to move the binding site across the membrane, coarse-grained simulations of multiple copies of MerF support the expectation that it functions as a monomer. Our results demonstrate how conformational changes and binding thermodynamics could lead to such a small membrane protein acting as an ion transporter. Published 2019. This article is a U.S. Government work and is in the public domain in the USA.
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Affiliation(s)
- Hyea Hwang
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
| | - Anthony Hazel
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332
| | - Peng Lian
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, 37996
| | - Jeremy C. Smith
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996
| | - James C. Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332
| | - Jerry M. Parks
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
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Gu RX, Baoukina S, Tieleman DP. Phase Separation in Atomistic Simulations of Model Membranes. J Am Chem Soc 2020; 142:2844-2856. [DOI: 10.1021/jacs.9b11057] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Ruo-Xu Gu
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
| | - Svetlana Baoukina
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
| | - D. Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive, N.W., Calgary, Alberta T2N 1N4, Canada
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40
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Favela-Rosales F, Galván-Hernández A, Hernández-Cobos J, Kobayashi N, Carbajal-Tinoco MD, Nakabayashi S, Ortega-Blake I. A molecular dynamics study proposing the existence of statistical structural heterogeneity due to chain orientation in the POPC-cholesterol bilayer. Biophys Chem 2019; 257:106275. [PMID: 31790909 DOI: 10.1016/j.bpc.2019.106275] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 10/02/2019] [Accepted: 10/21/2019] [Indexed: 01/08/2023]
Abstract
We performed molecular dynamics simulations of a lipid bilayer consisting of POPC and cholesterol at temperatures from 283 to 308K and cholesterol concentrations from 0 to 50% mol/mol. The purpose of this study was to look for the existence of structural differences in the region delimited by these parameters and, in particular, in a region where coexistence of liquid disordered and liquid ordered phases has been proposed. Our interest in this range of concentration and temperature responds to the fact that polyene ionophore activity varies considerably along it. Two force fields, CHARMM36 and Slipids, were compared in order to determine the most suitable. Both force fields predict non-monotonic behaviors consistent with the existence of phase transitions. We found the presence of lateral structural heterogeneity, statistical in nature, in some of the bilayers occurring in this range of temperatures and sterol concentrations. This heterogeneity was produced by correlated ordering of the POPC tails and not due to cholesterol enrichment, and lasts for tens of nanoseconds. We relate these observations to the action of polyenes in these membranes.
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Affiliation(s)
- Fernando Favela-Rosales
- Departamento de Física, Centro de Investigación y de Estudios Avanzados, Av. IPN No. 2508, México, DF, 07360, Mexico; Tecnológico Nacional de México, Campus Zacatecas Occidente, Ave. Tecnológico No. 2000, Col. Loma la Perla, Sombrerete, Zacatecas, 99102, Mexico
| | - Arturo Galván-Hernández
- Departamento de Física, Centro de Investigación y de Estudios Avanzados, Av. IPN No. 2508, México, DF, 07360, Mexico
| | - Jorge Hernández-Cobos
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México Av. Universidad s/n Cuernavaca, Morelos, 62251, Mexico
| | - Naritaka Kobayashi
- Department of Chemistry, Faculty of Science, Saitama University, Shimo-Ohkubo 255, Sakura-Ku, Saitama City, 338-8570, Japan
| | - Mauricio D Carbajal-Tinoco
- Departamento de Física, Centro de Investigación y de Estudios Avanzados, Av. IPN No. 2508, México, DF, 07360, Mexico
| | - Seiichiro Nakabayashi
- Department of Chemistry, Faculty of Science, Saitama University, Shimo-Ohkubo 255, Sakura-Ku, Saitama City, 338-8570, Japan
| | - Iván Ortega-Blake
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México Av. Universidad s/n Cuernavaca, Morelos, 62251, Mexico.
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41
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Shahane G, Ding W, Palaiokostas M, Azevedo HS, Orsi M. Interaction of Antimicrobial Lipopeptides with Bacterial Lipid Bilayers. J Membr Biol 2019; 252:317-329. [PMID: 31098677 PMCID: PMC6790193 DOI: 10.1007/s00232-019-00068-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 05/03/2019] [Indexed: 02/07/2023]
Abstract
The resistance of pathogens to traditional antibiotics is currently a global issue of enormous concern. As the discovery and development of new antibiotics become increasingly challenging, synthetic antimicrobial lipopeptides (AMLPs) are now receiving renewed attention as a new class of antimicrobial agents. In contrast to traditional antibiotics, AMLPs act by physically disrupting the cell membrane (rather than targeting specific proteins), thus reducing the risk of inducing bacterial resistance. In this study, we use microsecond-timescale atomistic molecular dynamics simulations to quantify the interaction of a short AMLP (C16-KKK) with model bacterial lipid bilayers. In particular, we investigate how fundamental transmembrane properties change in relation to a range of lipopeptide concentrations. A number of structural, mechanical, and dynamical features are found to be significantly altered in a non-linear fashion. At 10 mol% concentration, lipopeptides have a condensing effect on bacterial bilayers, characterized by a decrease in the area per lipid and an increase in the bilayer order. Higher AMLP concentrations of 25 and 40 mol% destabilize the membrane by disrupting the bilayer core structure, inducing membrane thinning and water leakage. Important transmembrane properties such as the lateral pressure and dipole potential profiles are also affected. Potential implications on membrane function and associated proteins are discussed.
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Affiliation(s)
- Ganesh Shahane
- Institute of Bioengineering, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Wei Ding
- School of Engineering & Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Michail Palaiokostas
- School of Engineering & Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Helena S Azevedo
- School of Engineering & Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Mario Orsi
- Department of Applied Sciences, University of the West of England, Coldharbour Lane, Bristol, BS16 1QY, UK.
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42
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Antimicrobial peptide ROAD-1 triggers phase change in local membrane environment to execute its activity. J Mol Model 2019; 25:281. [PMID: 31468141 DOI: 10.1007/s00894-019-4163-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 08/15/2019] [Indexed: 10/26/2022]
Abstract
Emergence of antibiotic-resistant pathogens has paved way for development of newer class of drugs that would not be susceptible to resistance. Antimicrobial peptides such as defensins that target the microbial membrane are promising candidates. ROAD-1 is an alpha-defensin present in the oral cavity of rhesus macaque and shares very high sequence similarity to human enteric defensin 5. In this study we have performed microsecond long all atom molecular dynamic simulations to understand the mechanism of action of ROAD-1. We find that ROAD-1 is able to adopt an energetically stable conformation predominantly stabilized by electrostatic interactions only in presence of bacterial membranes. In mammalian membrane even though it gets absorbed onto the bilayer, it is unable to adopt an equilibrium conformation. Binding of ROAD-1 to bilayer induces clustering of POPG molecules up to 15 Å around the peptide. POPG molecules show higher order parameters than the neighboring POPE implying coexistence of different phases. Analysis of binding free energy of ROAD-1-membrane complex indicates Arg1, Arg2, Arg7, and Arg25 to play key role in its antimicrobial activity. Unlike its homolog HD5, ROAD-1 is not observed to form a dimer. Our study gives insight into the membrane-bound conformation of ROAD-1 and its mechanism of action that can aid in designing defensin-based therapeutics. Graphical abstract Antimicrobial peptide ROAD-1 adopts a different membrane-bound conformation as compared with HD5 even though they belong to the same family implying a different mechanism of action.
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43
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Balusek C, Hwang H, Lau CH, Lundquist K, Hazel A, Pavlova A, Lynch DL, Reggio PH, Wang Y, Gumbart JC. Accelerating Membrane Simulations with Hydrogen Mass Repartitioning. J Chem Theory Comput 2019; 15:4673-4686. [PMID: 31265271 PMCID: PMC7271963 DOI: 10.1021/acs.jctc.9b00160] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The time step of atomistic molecular dynamics (MD) simulations is determined by the fastest motions in the system and is typically limited to 2 fs. An increasingly popular approach is to increase the mass of the hydrogen atoms to ∼3 amu and decrease the mass of the parent atom by an equivalent amount. This approach, known as hydrogen-mass repartitioning (HMR), permits time steps up to 4 fs with reasonable simulation stability. While HMR has been applied in many published studies to date, it has not been extensively tested for membrane-containing systems. Here, we compare the results of simulations of a variety of membranes and membrane-protein systems run using a 2 fs time step and a 4 fs time step with HMR. For pure membrane systems, we find almost no difference in structural properties, such as area-per-lipid, electron density profiles, and order parameters, although there are differences in kinetic properties such as the diffusion constant. Conductance through a porin in an applied field, partitioning of a small peptide, hydrogen-bond dynamics, and membrane mixing show very little dependence on HMR and the time step. We also tested a 9 Å cutoff as compared to the standard CHARMM cutoff of 12 Å, finding significant deviations in many properties tested. We conclude that HMR is a valid approach for membrane systems, but a 9 Å cutoff is not.
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Affiliation(s)
| | | | - Chun Hon Lau
- Department of Physics , The Chinese University of Hong Kong , Shatin, NT, Hong Kong , People's Republic of China
| | | | | | | | - Diane L Lynch
- Department of Chemistry and Biochemistry , University of North Carolina , Greensboro , North Carolina 27402 , United States
| | - Patricia H Reggio
- Department of Chemistry and Biochemistry , University of North Carolina , Greensboro , North Carolina 27402 , United States
| | - Yi Wang
- Department of Physics , The Chinese University of Hong Kong , Shatin, NT, Hong Kong , People's Republic of China
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A selective membrane-targeting repurposed antibiotic with activity against persistent methicillin-resistant Staphylococcus aureus. Proc Natl Acad Sci U S A 2019; 116:16529-16534. [PMID: 31358625 DOI: 10.1073/pnas.1904700116] [Citation(s) in RCA: 106] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Treatment of Staphylococcus aureus infections is complicated by the development of antibiotic tolerance, a consequence of the ability of S. aureus to enter into a nongrowing, dormant state in which the organisms are referred to as persisters. We report that the clinically approved anthelmintic agent bithionol kills methicillin-resistant S. aureus (MRSA) persister cells, which correlates with its ability to disrupt the integrity of Gram-positive bacterial membranes. Critically, bithionol exhibits significant selectivity for bacterial compared with mammalian cell membranes. All-atom molecular dynamics (MD) simulations demonstrate that the selectivity of bithionol for bacterial membranes correlates with its ability to penetrate and embed in bacterial-mimic lipid bilayers, but not in cholesterol-rich mammalian-mimic lipid bilayers. In addition to causing rapid membrane permeabilization, the insertion of bithionol increases membrane fluidity. By using bithionol and nTZDpa (another membrane-active antimicrobial agent), as well as analogs of these compounds, we show that the activity of membrane-active compounds against MRSA persisters positively correlates with their ability to increase membrane fluidity, thereby establishing an accurate biophysical indicator for estimating antipersister potency. Finally, we demonstrate that, in combination with gentamicin, bithionol effectively reduces bacterial burdens in a mouse model of chronic deep-seated MRSA infection. This work highlights the potential repurposing of bithionol as an antipersister therapeutic agent.
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Zhang Y, Chan C, Li Z, Ma J, Meng Q, Zhi C, Sun H, Fan J. Nanotoxicity of Boron Nitride Nanosheet to Bacterial Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:6179-6187. [PMID: 30955333 DOI: 10.1021/acs.langmuir.9b00025] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Boron nitride (BN) nanosheet is a novel material with great potential in biomedical applications. A deep understanding of the basic interaction mechanisms between biosystems and foreign BN nanosheets can help to better clarify the potential risks of these nanomaterials and provide guidance on their safe design. In this paper, we show that BN nanosheets can cause degradation of bacterial cell membranes via experimental and simulation-based approaches. Our extensive molecular dynamics simulations results reveal that BN nanosheets cause toxicity to both bacterial outer and inner membranes in which hydrophobic effect plays an important role. The spontaneous lipid extraction by BN nanosheets is in agreement with the free-energy calculations. A liquid-to-gel phase transition is induced by the BN nanosheet in the outer model membrane of bacteria, indicating that the BN nanosheet may cause higher toxicity to the outer membrane than to the inner membrane. Our findings may offer new insights into the molecular basis of BN's cytotoxicity and antibacterial activity.
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Affiliation(s)
- Yonghui Zhang
- School of Materials and Energy , Guangdong University of Technology , No. 100 Waihuan Xi Road , Guangzhou Higher Education Mega Center, Panyu District, Guangzhou 510006 , China
| | | | | | | | | | | | - Hongyan Sun
- Key Laboratory of Biochip Technology, Biotech and Health Centre , Shenzhen Research Institute of City University of Hong Kong , Shenzhen 518057 , China
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Shahane G, Ding W, Palaiokostas M, Orsi M. Physical properties of model biological lipid bilayers: insights from all-atom molecular dynamics simulations. J Mol Model 2019; 25:76. [PMID: 30806797 DOI: 10.1007/s00894-019-3964-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 02/07/2019] [Indexed: 02/04/2023]
Abstract
The physical properties of lipid bilayers are sensitive to the specific type and composition of the lipids that make up the many different types of cell membranes. Studying model bilayers of representative heterogeneous compositions can provide key insights into membrane functionality. In this work, we use atomistic molecular dynamics simulations to characterize key properties in a number of bilayer membranes of varying composition. We first examine basic properties, such as lipid area, volume, and bilayer thickness, of simple, homogeneous bilayers comprising several lipid types, which are prevalent in biological membranes. Such lipids are then used in simulations of heterogeneous systems representative of bacterial, mammalian, and cancer membranes. Our analysis is especially focused on depth-dependent, transmembrane profiles; in particular, we calculate lateral pressure and dipole potential profiles, two fundamental properties which play key roles in a large number of biological functions.
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Affiliation(s)
- Ganesh Shahane
- Institute of Bioengineering, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Wei Ding
- School of Engineering & Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Michail Palaiokostas
- School of Engineering & Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Mario Orsi
- Department of Applied Sciences, University of the West of England, Coldharbour Lane, Bristol, BS16 1QY, UK.
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Leonard AN, Wang E, Monje-Galvan V, Klauda JB. Developing and Testing of Lipid Force Fields with Applications to Modeling Cellular Membranes. Chem Rev 2019; 119:6227-6269. [DOI: 10.1021/acs.chemrev.8b00384] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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48
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Affiliation(s)
- Xiaolin Cheng
- Division of Medicinal Chemistry and Pharmacognosy, Biophysics Graduate Program, Translational Data Analytics Institute, The Ohio State University, Columbus, Ohio 43210, United States
| | - Jeremy C. Smith
- UT/ORNL Center for Molecular Biophysics, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6309, United States
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996, United States
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49
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An Y, Bejagam KK, Deshmukh SA. Development of Transferable Nonbonded Interactions between Coarse-Grained Hydrocarbon and Water Models. J Phys Chem B 2019; 123:909-921. [DOI: 10.1021/acs.jpcb.8b07990] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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50
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Oroskar PA, Jameson CJ, Murad S. Molecular-Level "Observations" of the Behavior of Gold Nanoparticles in Aqueous Solution and Interacting with a Lipid Bilayer Membrane. Methods Mol Biol 2019; 2000:303-359. [PMID: 31148024 DOI: 10.1007/978-1-4939-9516-5_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We use coarse-grained molecular dynamics simulations to "observe" details of interactions between ligand-covered gold nanoparticles and a lipid bilayer model membrane. In molecular dynamics simulations, one puts the individual atoms and groups of atoms of the physical system to be "observed" into a simulation box, specifies the forms of the potential energies of interactions between them (ultimately quantum based), and lets them individually move classically according to Newton's equations of motion, based on the forces arising from the assumed potential energy forms. The atoms that are chemically bonded to each other stay chemically bonded, following known potentials (force fields) that permit internal degrees of freedom (internal rotation, torsion, vibrations), and the interactions between nonbonded atoms are simplified to Lennard-Jones forms (in our case) and coulombic (where electrical charges are present) in which the parameters are previously optimized to reproduce thermodynamic properties or are based on quantum electronic calculations. The system is started out at a reasonable set of coordinates for all atoms or groups of atoms, and then permitted to develop according to the equations of motion, one small step (usually 10 fs time step) at a time, for millions of steps until the system is at a quasi-equilibrium (usually reached after hundreds of nanoseconds). We then let the system play out its motions further for many nanoseconds to observe the behavior, periodically taking snapshots (saving all positions and energies), and post-processing the snapshots to obtain various average descriptions of the system. Alkanethiols of various lengths serve as examples of hydrophobic ligands and methyl-terminated PEG with various numbers of monomer units serve as examples of hydrophilic ligands. Spherical gold particles of various diameters as well as gold nanorods form the core to which ligands are attached. The nanoparticles are characterized at the molecular level, especially the distributions of ligand configurations and their dependence on ligand length, and surface coverage. Self-assembly of the bilayer from an isotropic solution and observation of membrane properties that correspond well to experimental values validate the simulations. The mechanism of permeation of a gold NP coated with either a hydrophobic or a hydrophilic ligand, and its dependence on surface coverage, ligand length, core diameter, and core shape, is investigated. Lipid response such as lipid flip-flops, lipid extraction, and changes in order parameter of the lipid tails are examined in detail. The mechanism of permeation of a PEGylated nanorod is shown to occur by tilting, lying down, rotating, and straightening up. The nature of the information provided by molecular dynamics simulations permits understanding of the detailed behavior of gold nanoparticles interacting with lipid membranes which in turn helps to understand why some known systems work better than others and aids the design of new particles and improvement of methods for preparing existing ones.
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Affiliation(s)
- Priyanka A Oroskar
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, IL, USA
| | - Cynthia J Jameson
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, USA
| | - Sohail Murad
- Department of Chemical Engineering, University of Illinois at Chicago, Chicago, IL, USA.
- Department of Chemical Engineering, Illinois Institute of Technology, Chicago, IL, USA.
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