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Santos DS, De Nicola A, dos Santos VF, Milano G, Soares TA. Exploring the Molecular Dynamics of a Lipid-A Vesicle at the Atom Level: Morphology and Permeation Mechanism. J Phys Chem B 2023; 127:6694-6702. [PMID: 37467380 PMCID: PMC10405212 DOI: 10.1021/acs.jpcb.3c02848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/18/2023] [Indexed: 07/21/2023]
Abstract
Lipid-A was previously shown to spontaneously aggregate into a vesicle via the hybrid particle field approach. We assess the validity of the proposed vesiculation mechanism by simulating the resulting lipid-A vesicle at the atom level. The spatial confinement imposed by the vesicle geometry on the conformation and packing of lipid-A induces significant heterogeneity of physical properties in the inner and outer leaflets. It also induces tighter molecular packing and lower acyl chain order compared to the lamellar arrangement. Around 5% of water molecules passively permeates the vesicle membrane inward and outward. The permeation is facilitated by interactions with water molecules that are transported across the membrane by a network of electrostatic interactions with the hydrogen bond donors/acceptors in the N-acetylglucosamine ring and upper region of the acyl chains of lipid-A. The permeation process takes place at low rates but still at higher frequencies than observed for the lamellar arrangement of lipid-A. These findings not only substantiate the proposed lipid-A vesiculation mechanism but also reveal the complex structural dynamics of an important nonlamellar arrangement of lipid-A.
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Affiliation(s)
- Denys
E. S. Santos
- Departmento
de Química Fundamental, Universidade
Federal de Pernambuco, Recife 50740-560, Brazil
| | - Antonio De Nicola
- Scuola
Superiore Meridionale, Largo S. Marcellino 10, Napoli 80138, Italy
- Graduate
School of Organic Materials Science, Yamagata
University, Yonezawa 992-8510, Yamagata, Japan
| | - Vinicius F. dos Santos
- Departamento
de Química, Faculdade de Filosofia, Ciências e Letras
de Ribeirão Preto, Universidade de
São Paulo, Ribeirão
Preto 14040-901, Brazil
| | - Giuseppe Milano
- Department
of Chemical, Materials and Production Engineering, University of Naples Federico II, Piazzale Tecchio 80, Napoli 80125, Italy
| | - Thereza A. Soares
- Departamento
de Química, Faculdade de Filosofia, Ciências e Letras
de Ribeirão Preto, Universidade de
São Paulo, Ribeirão
Preto 14040-901, Brazil
- Hylleraas
Centre for Quantum Molecular Sciences, University
of Oslo, Oslo 0315, Norway
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2
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Vermaas JV, Crowley MF, Beckham GT. Molecular simulation of lignin-related aromatic compound permeation through gram-negative bacterial outer membranes. J Biol Chem 2022; 298:102627. [PMID: 36273587 PMCID: PMC9720347 DOI: 10.1016/j.jbc.2022.102627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 10/14/2022] [Accepted: 10/15/2022] [Indexed: 12/12/2022] Open
Abstract
Lignin, an abundant aromatic heteropolymer in secondary plant cell walls, is the single largest source of renewable aromatics in the biosphere. Leveraging this resource for renewable bioproducts through targeted microbial action depends on lignin fragment uptake by microbial hosts and subsequent enzymatic action to obtain the desired product. Recent computational work has emphasized that bacterial inner membranes are permeable to many aromatic compounds expected from lignin depolymerization processes. In this study, we expand on these findings through simulations for 42 lignin-related compounds across a gram-negative bacterial outer membrane model. Unbiased simulation trajectories indicate that spontaneous crossing for the full outer membrane is relatively rare at molecular simulation timescales, primarily due to preferential membrane partitioning and slow diffusion within the lipopolysaccharide layer within the outer membrane. Membrane partitioning and permeability coefficients were determined through replica exchange umbrella sampling simulations to overcome sampling limitations. We find that the glycosylated lipopolysaccharides found in the outer membrane increase the permeation barrier to many lignin-related compounds, particularly the most hydrophobic compounds. However, the effect is relatively modest; at industrially relevant concentrations, uncharged lignin-related compounds will readily diffuse across the outer membrane without the need for specific porins. Together, our results provide insight into the permeability of the bacterial outer membrane for assessing lignin fragment uptake and the future production of renewable bioproducts.
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Affiliation(s)
- Josh V. Vermaas
- Biosciences Center, National Renewable Energy Laboratory, Golden, Colorado, USA,National Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA,MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan, USA,Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA,For correspondence: Josh V. Vermaas; Michael F. Crowley; Gregg T. Beckham
| | - Michael F. Crowley
- Renewable Resources and Enabling Sciences Center, National Renewable Energy, Laboratory, Golden, Colorado, USA,For correspondence: Josh V. Vermaas; Michael F. Crowley; Gregg T. Beckham
| | - Gregg T. Beckham
- Renewable Resources and Enabling Sciences Center, National Renewable Energy, Laboratory, Golden, Colorado, USA,For correspondence: Josh V. Vermaas; Michael F. Crowley; Gregg T. Beckham
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3
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Khalid S, Schroeder C, Bond PJ, Duncan AL. What have molecular simulations contributed to understanding of Gram-negative bacterial cell envelopes? MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35294337 PMCID: PMC9558347 DOI: 10.1099/mic.0.001165] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Bacterial cell envelopes are compositionally complex and crowded and while highly dynamic in some areas, their molecular motion is very limited, to the point of being almost static in others. Therefore, it is no real surprise that studying them at high resolution across a range of temporal and spatial scales requires a number of different techniques. Details at atomistic to molecular scales for up to tens of microseconds are now within range for molecular dynamics simulations. Here we review how such simulations have contributed to our current understanding of the cell envelopes of Gram-negative bacteria.
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Affiliation(s)
- Syma Khalid
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Cyril Schroeder
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Peter J Bond
- Bioinformatics Institute (A*STAR), Singapore 138671, Singapore.,Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore
| | - Anna L Duncan
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
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4
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Out of Sight, Out of Mind: The Effect of the Equilibration Protocol on the Structural Ensembles of Charged Glycolipid Bilayers. Molecules 2020; 25:molecules25215120. [PMID: 33158044 PMCID: PMC7663769 DOI: 10.3390/molecules25215120] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/28/2020] [Accepted: 10/30/2020] [Indexed: 11/16/2022] Open
Abstract
Molecular dynamics (MD) simulations represent an essential tool in the toolbox of modern chemistry, enabling the prediction of experimental observables for a variety of chemical systems and processes and majorly impacting the study of biological membranes. However, the chemical diversity of complex lipids beyond phospholipids brings new challenges to well-established protocols used in MD simulations of soft matter and requires continuous assessment to ensure simulation reproducibility and minimize unphysical behavior. Lipopolysaccharides (LPS) are highly charged glycolipids whose aggregation in a lamellar arrangement requires the binding of numerous cations to oppositely charged groups deep inside the membrane. The delicate balance between the fully hydrated carbohydrate region and the smaller hydrophobic core makes LPS membranes very sensitive to the choice of equilibration protocol. In this work, we show that the protocol successfully used to equilibrate phospholipid bilayers when applied to complex lipopolysaccharide membranes occasionally leads to a small expansion of the simulation box very early in the equilibration phase. Although the use of a barostat algorithm controls the system dimension and particle distances according to the target pressure, fluctuation in the fleeting pressure occasionally enables a few water molecules to trickle into the hydrophobic region of the membrane, with spurious solvent buildup. We show that this effect stems from the initial steps of NPT equilibration, where initial pressure can be fairly high. This can be solved with the use of a stepwise-thermalization NVT/NPT protocol, as demonstrated for atomistic MD simulations of LPS/DPPE and lipid-A membranes in the presence of different salts using an extension of the GROMOS forcefield within the GROMACS software. This equilibration protocol should be standard procedure for the generation of consistent structural ensembles of charged glycolipids starting from atomic coordinates not previously pre-equilibrated. Although different ways to deal with this issue can be envisioned, we investigated one alternative that could be readily available in major MD engines with general users in mind.
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5
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Martinotti C, Ruiz-Perez L, Deplazes E, Mancera RL. Molecular Dynamics Simulation of Small Molecules Interacting with Biological Membranes. Chemphyschem 2020; 21:1486-1514. [PMID: 32452115 DOI: 10.1002/cphc.202000219] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 05/22/2020] [Indexed: 12/12/2022]
Abstract
Cell membranes protect and compartmentalise cells and their organelles. The semi-permeable nature of these membranes controls the exchange of solutes across their structure. Characterising the interaction of small molecules with biological membranes is critical to understanding of physiological processes, drug action and permeation, and many biotechnological applications. This review provides an overview of how molecular simulations are used to study the interaction of small molecules with biological membranes, with a particular focus on the interactions of water, organic compounds, drugs and short peptides with models of plasma cell membrane and stratum corneum lipid bilayers. This review will not delve on other types of membranes which might have different composition and arrangement, such as thylakoid or mitochondrial membranes. The application of unbiased molecular dynamics simulations and enhanced sampling methods such as umbrella sampling, metadynamics and replica exchange are described using key examples. This review demonstrates how state-of-the-art molecular simulations have been used successfully to describe the mechanism of binding and permeation of small molecules with biological membranes, as well as associated changes to the structure and dynamics of these membranes. The review concludes with an outlook on future directions in this field.
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Affiliation(s)
- Carlo Martinotti
- School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute and, Curtin Institute for Computation, Curtin University, Perth, WA 6845, Australia
| | - Lanie Ruiz-Perez
- School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute and, Curtin Institute for Computation, Curtin University, Perth, WA 6845, Australia
| | - Evelyne Deplazes
- School of Life Sciences, University of Technology Sydney, Sydney, NSW 2007, Australia
| | - Ricardo L Mancera
- School of Pharmacy and Biomedical Sciences, Curtin Health Innovation Research Institute and, Curtin Institute for Computation, Curtin University, Perth, WA 6845, Australia
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6
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Aprà E, Bylaska EJ, de Jong WA, Govind N, Kowalski K, Straatsma TP, Valiev M, van Dam HJJ, Alexeev Y, Anchell J, Anisimov V, Aquino FW, Atta-Fynn R, Autschbach J, Bauman NP, Becca JC, Bernholdt DE, Bhaskaran-Nair K, Bogatko S, Borowski P, Boschen J, Brabec J, Bruner A, Cauët E, Chen Y, Chuev GN, Cramer CJ, Daily J, Deegan MJO, Dunning TH, Dupuis M, Dyall KG, Fann GI, Fischer SA, Fonari A, Früchtl H, Gagliardi L, Garza J, Gawande N, Ghosh S, Glaesemann K, Götz AW, Hammond J, Helms V, Hermes ED, Hirao K, Hirata S, Jacquelin M, Jensen L, Johnson BG, Jónsson H, Kendall RA, Klemm M, Kobayashi R, Konkov V, Krishnamoorthy S, Krishnan M, Lin Z, Lins RD, Littlefield RJ, Logsdail AJ, Lopata K, Ma W, Marenich AV, Martin Del Campo J, Mejia-Rodriguez D, Moore JE, Mullin JM, Nakajima T, Nascimento DR, Nichols JA, Nichols PJ, Nieplocha J, Otero-de-la-Roza A, Palmer B, Panyala A, Pirojsirikul T, Peng B, Peverati R, Pittner J, Pollack L, Richard RM, Sadayappan P, Schatz GC, Shelton WA, Silverstein DW, Smith DMA, Soares TA, Song D, Swart M, Taylor HL, Thomas GS, Tipparaju V, Truhlar DG, Tsemekhman K, Van Voorhis T, Vázquez-Mayagoitia Á, Verma P, Villa O, Vishnu A, Vogiatzis KD, Wang D, Weare JH, Williamson MJ, Windus TL, Woliński K, Wong AT, Wu Q, Yang C, Yu Q, Zacharias M, Zhang Z, Zhao Y, Harrison RJ. NWChem: Past, present, and future. J Chem Phys 2020; 152:184102. [PMID: 32414274 DOI: 10.1063/5.0004997] [Citation(s) in RCA: 302] [Impact Index Per Article: 75.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Specialized computational chemistry packages have permanently reshaped the landscape of chemical and materials science by providing tools to support and guide experimental efforts and for the prediction of atomistic and electronic properties. In this regard, electronic structure packages have played a special role by using first-principle-driven methodologies to model complex chemical and materials processes. Over the past few decades, the rapid development of computing technologies and the tremendous increase in computational power have offered a unique chance to study complex transformations using sophisticated and predictive many-body techniques that describe correlated behavior of electrons in molecular and condensed phase systems at different levels of theory. In enabling these simulations, novel parallel algorithms have been able to take advantage of computational resources to address the polynomial scaling of electronic structure methods. In this paper, we briefly review the NWChem computational chemistry suite, including its history, design principles, parallel tools, current capabilities, outreach, and outlook.
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Affiliation(s)
- E Aprà
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - E J Bylaska
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - W A de Jong
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - N Govind
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - K Kowalski
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - T P Straatsma
- National Center for Computational Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M Valiev
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - H J J van Dam
- Brookhaven National Laboratory, Upton, New York 11973, USA
| | - Y Alexeev
- Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - J Anchell
- Intel Corporation, Santa Clara, California 95054, USA
| | - V Anisimov
- Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - F W Aquino
- QSimulate, Cambridge, Massachusetts 02139, USA
| | - R Atta-Fynn
- Department of Physics, The University of Texas at Arlington, Arlington, Texas 76019, USA
| | - J Autschbach
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, USA
| | - N P Bauman
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - J C Becca
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - D E Bernholdt
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | | | - S Bogatko
- 4G Clinical, Wellesley, Massachusetts 02481, USA
| | - P Borowski
- Faculty of Chemistry, Maria Curie-Skłodowska University in Lublin, 20-031 Lublin, Poland
| | - J Boschen
- Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA
| | - J Brabec
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, 18223 Prague 8, Czech Republic
| | - A Bruner
- Department of Chemistry and Physics, University of Tennessee at Martin, Martin, Tennessee 38238, USA
| | - E Cauët
- Service de Chimie Quantique et Photophysique (CP 160/09), Université libre de Bruxelles, B-1050 Brussels, Belgium
| | - Y Chen
- Facebook, Menlo Park, California 94025, USA
| | - G N Chuev
- Institute of Theoretical and Experimental Biophysics, Russian Academy of Science, Pushchino, Moscow Region 142290, Russia
| | - C J Cramer
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - J Daily
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - M J O Deegan
- SKAO, Jodrell Bank Observatory, Macclesfield SK11 9DL, United Kingdom
| | - T H Dunning
- Department of Chemistry, University of Washington, Seattle, Washington 98195, USA
| | - M Dupuis
- Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260, USA
| | - K G Dyall
- Dirac Solutions, Portland, Oregon 97229, USA
| | - G I Fann
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - S A Fischer
- Chemistry Division, U. S. Naval Research Laboratory, Washington, DC 20375, USA
| | - A Fonari
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - H Früchtl
- EaStCHEM and School of Chemistry, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom
| | - L Gagliardi
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - J Garza
- Departamento de Química, División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana-Iztapalapa, Col. Vicentina, Iztapalapa, C.P. 09340 Ciudad de México, Mexico
| | - N Gawande
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - S Ghosh
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 5545, USA
| | - K Glaesemann
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - A W Götz
- San Diego Supercomputer Center, University of California, San Diego, La Jolla, California 92093, USA
| | - J Hammond
- Intel Corporation, Santa Clara, California 95054, USA
| | - V Helms
- Center for Bioinformatics, Saarland University, D-66041 Saarbrücken, Germany
| | - E D Hermes
- Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, USA
| | - K Hirao
- Next-generation Molecular Theory Unit, Advanced Science Institute, RIKEN, Saitama 351-0198, Japan
| | - S Hirata
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA
| | - M Jacquelin
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - L Jensen
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - B G Johnson
- Acrobatiq, Pittsburgh, Pennsylvania 15206, USA
| | - H Jónsson
- Faculty of Physical Sciences, University of Iceland, Reykjavík, Iceland and Department of Applied Physics, Aalto University, FI-00076 Aalto, Espoo, Finland
| | - R A Kendall
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - M Klemm
- Intel Corporation, Santa Clara, California 95054, USA
| | - R Kobayashi
- ANU Supercomputer Facility, Australian National University, Canberra, Australia
| | - V Konkov
- Chemistry Program, Florida Institute of Technology, Melbourne, Florida 32901, USA
| | - S Krishnamoorthy
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - M Krishnan
- Facebook, Menlo Park, California 94025, USA
| | - Z Lin
- Department of Physics, University of Science and Technology of China, Hefei, China
| | - R D Lins
- Aggeu Magalhaes Institute, Oswaldo Cruz Foundation, Recife, Brazil
| | | | - A J Logsdail
- Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Cardiff, Wales CF10 3AT, United Kingdom
| | - K Lopata
- Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| | - W Ma
- Institute of Software, Chinese Academy of Sciences, Beijing, China
| | - A V Marenich
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - J Martin Del Campo
- Departamento de Física y Química Teórica, Facultad de Química, Universidad Nacional Autónoma de México, México City, Mexico
| | - D Mejia-Rodriguez
- Quantum Theory Project, Department of Physics, University of Florida, Gainesville, Florida 32611, USA
| | - J E Moore
- Intel Corporation, Santa Clara, California 95054, USA
| | - J M Mullin
- DCI-Solutions, Aberdeen Proving Ground, Maryland 21005, USA
| | - T Nakajima
- Computational Molecular Science Research Team, RIKEN Center for Computational Science, Kobe, Hyogo 650-0047, Japan
| | - D R Nascimento
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - J A Nichols
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - P J Nichols
- Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - J Nieplocha
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - A Otero-de-la-Roza
- Departamento de Química Física y Analítica, Facultad de Química, Universidad de Oviedo, 33006 Oviedo, Spain
| | - B Palmer
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - A Panyala
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - T Pirojsirikul
- Department of Chemistry, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand
| | - B Peng
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - R Peverati
- Chemistry Program, Florida Institute of Technology, Melbourne, Florida 32901, USA
| | - J Pittner
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., 18223 Prague 8, Czech Republic
| | - L Pollack
- StudyPoint, Boston, Massachusetts 02114, USA
| | | | - P Sadayappan
- School of Computing, University of Utah, Salt Lake City, Utah 84112, USA
| | - G C Schatz
- Department of Chemistry, Northwestern University, Evanston, Illinois 60208, USA
| | - W A Shelton
- Cain Department of Chemical Engineering, Louisiana State University, Baton Rouge, Louisiana 70803, USA
| | | | - D M A Smith
- Intel Corporation, Santa Clara, California 95054, USA
| | - T A Soares
- Dept. of Fundamental Chemistry, Universidade Federal de Pernambuco, Recife, Brazil
| | - D Song
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - M Swart
- ICREA, 08010 Barcelona, Spain and Universitat Girona, Institut de Química Computacional i Catàlisi, Campus Montilivi, 17003 Girona, Spain
| | - H L Taylor
- CD-adapco/Siemens, Melville, New York 11747, USA
| | - G S Thomas
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - V Tipparaju
- Cray Inc., Bloomington, Minnesota 55425, USA
| | - D G Truhlar
- Department of Chemistry, Chemical Theory Center, and Supercomputing Institute, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | | | - T Van Voorhis
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Á Vázquez-Mayagoitia
- Argonne Leadership Computing Facility, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - P Verma
- 1QBit, Vancouver, British Columbia V6E 4B1, Canada
| | - O Villa
- NVIDIA, Santa Clara, California 95051, USA
| | - A Vishnu
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - K D Vogiatzis
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - D Wang
- College of Physics and Electronics, Shandong Normal University, Jinan, Shandong 250014, China
| | - J H Weare
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, USA
| | - M J Williamson
- Department of Chemistry, Cambridge University, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - T L Windus
- Department of Chemistry, Iowa State University and Ames Laboratory, Ames, Iowa 50011, USA
| | - K Woliński
- Faculty of Chemistry, Maria Curie-Skłodowska University in Lublin, 20-031 Lublin, Poland
| | - A T Wong
- Qwil, San Francisco, California 94107, USA
| | - Q Wu
- Brookhaven National Laboratory, Upton, New York 11973, USA
| | - C Yang
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Q Yu
- AMD, Santa Clara, California 95054, USA
| | - M Zacharias
- Department of Physics, Technical University of Munich, 85748 Garching, Germany
| | - Z Zhang
- Stanford Research Computing Center, Stanford University, Stanford, California 94305, USA
| | - Y Zhao
- State Key Laboratory of Silicate Materials for Architectures, International School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China
| | - R J Harrison
- Institute for Advanced Computational Science, Stony Brook University, Stony Brook, New York 11794, USA
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7
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Abstract
Gram-negative bacteria are protected by a multicompartmental molecular architecture known as the cell envelope that contains two membranes and a thin cell wall. As the cell envelope controls influx and efflux of molecular species, in recent years both experimental and computational studies of such architectures have seen a resurgence due to the implications for antibiotic development. In this article we review recent progress in molecular simulations of bacterial membranes. We show that enormous progress has been made in terms of the lipidic and protein compositions of bacterial systems. The simulations have moved away from the traditional setup of one protein surrounded by a large patch of the same lipid type toward a more bio-logically representative viewpoint. Simulations with multiple cell envelope components are also emerging. We review some of the key method developments that have facilitated recent progress, discuss some current limitations, and offer a perspective on future directions.
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Affiliation(s)
- Wonpil Im
- Departments of Biological Sciences and Bioengineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA
- School of Computational Sciences, Korea Institute for Advanced Study, Seoul 02455, Republic of Korea
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton S017 1BJ, United Kingdom
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8
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Aggregation of Lipid A Variants: A Hybrid Particle-Field Model. Biochim Biophys Acta Gen Subj 2020; 1865:129570. [PMID: 32105775 DOI: 10.1016/j.bbagen.2020.129570] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/10/2020] [Accepted: 02/19/2020] [Indexed: 12/23/2022]
Abstract
Lipid A is one of the three components of bacterial lipopolysaccharides constituting the outer membrane of Gram-negative bacteria, and is recognized to have an important biological role in the inflammatory response of mammalians. Its biological activity is modulated by the number of acyl-chains that are present in the lipid and by the dielectric medium, i.e., the type of counter-ions, through electrostatic interactions. In this paper, we report on a coarse-grained model of chemical variants of Lipid A based on the hybrid particle-field/molecular dynamics approach (hPF-MD). In particular, we investigate the stability of Lipid A bilayers for two different hexa- and tetra-acylated structures. Comparing particle density profiles along bilayer cross-sections, we find good agreement between the hPF-MD model and reference all-atom simulation for both chemical variants of Lipid A. hPF-MD models of constituted bilayers composed by hexa-acylated Lipid A in water are stable within the simulation time. We further validate our model by verifying that the phase behavior of Lipid A/counterion/water mixtures is correctly reproduced. In particular, hPF-MD simulations predict the correct self-assembly of different lamellar and micellar phases from an initially random distribution of Lipid A molecules with counterions in water. Finally, it is possible to observe the spontaneous formation and stability of Lipid A vesicles by fusion of micellar aggregates.
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9
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Jefferies D, Khalid S. Atomistic and coarse-grained simulations of membrane proteins: A practical guide. Methods 2020; 185:15-27. [PMID: 32084518 DOI: 10.1016/j.ymeth.2020.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 02/07/2020] [Accepted: 02/14/2020] [Indexed: 12/12/2022] Open
Abstract
Membrane proteins are amphipathic macromolecules whose exposed hydrophobic surfaces promote interactions with lipid membranes. Membrane proteins are remarkably diverse in terms of chemical composition and correspondingly, their biological functions and general biophysical behavior. Conventional experimental techniques provide an approach to study specific properties of membrane proteins e.g. their surface features, the nature and abundance of stabilizing intramolecular forces, preferred bilayer orientation, and the characteristics of their annular lipid shells. Molecular modeling software-and in particular, the suite of molecular dynamics algorithms-enables a more comprehensive exploration of dynamic membrane protein behavior. Molecular dynamics methods enable users to produce stepwise trajectories of proteins on arbitrary spatiotemporal scales that enable the easy identification of dynamic interactions that are beyond the scope of conventional analytical techniques. This article explains the molecular dynamics theoretical framework and popular step-by-step approaches for simulating membrane proteins in planar, and to a lesser extent, nonplanar lipid geometries. We detail popular procedures and computational tools that produce well-packed configurations of lipids and proteins and additionally, the efficient molecular dynamics simulation algorithms that reproduce their dynamic interactions.
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Affiliation(s)
- Damien Jefferies
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK.
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10
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Domínguez-Medina CC, Pérez-Toledo M, Schager AE, Marshall JL, Cook CN, Bobat S, Hwang H, Chun BJ, Logan E, Bryant JA, Channell WM, Morris FC, Jossi SE, Alshayea A, Rossiter AE, Barrow PA, Horsnell WG, MacLennan CA, Henderson IR, Lakey JH, Gumbart JC, López-Macías C, Bavro VN, Cunningham AF. Outer membrane protein size and LPS O-antigen define protective antibody targeting to the Salmonella surface. Nat Commun 2020; 11:851. [PMID: 32051408 PMCID: PMC7015928 DOI: 10.1038/s41467-020-14655-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 01/23/2020] [Indexed: 11/28/2022] Open
Abstract
Lipopolysaccharide (LPS) O-antigen (O-Ag) is known to limit antibody binding to surface antigens, although the relationship between antibody, O-Ag and other outer-membrane antigens is poorly understood. Here we report, immunization with the trimeric porin OmpD from Salmonella Typhimurium (STmOmpD) protects against infection. Atomistic molecular dynamics simulations indicate this is because OmpD trimers generate footprints within the O-Ag layer sufficiently sized for a single IgG Fab to access. While STmOmpD differs from its orthologue in S. Enteritidis (SEn) by a single amino-acid residue, immunization with STmOmpD confers minimal protection to SEn. This is due to the OmpD-O-Ag interplay restricting IgG binding, with the pairing of OmpD with its native O-Ag being essential for optimal protection after immunization. Thus, both the chemical and physical structure of O-Ag are key for the presentation of specific epitopes within proteinaceous surface-antigens. This enhances combinatorial antigenic diversity in Gram-negative bacteria, while reducing associated fitness costs. The O-antigen of LPS is known to limit the binding of antibody to bacterial surface antigens. Here the AUs show that the chemical and physical structure of the O-antigen are central factors in limiting the exposure of surface antigens to antibodies during Salmonella infection, thus defining their protective qualities.
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Affiliation(s)
- C Coral Domínguez-Medina
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, B15 2TT, UK.,Institute of Microbiology and Infection, University of Birmingham, Birmingham, B15 2TT, UK
| | - Marisol Pérez-Toledo
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, B15 2TT, UK.,Institute of Microbiology and Infection, University of Birmingham, Birmingham, B15 2TT, UK.,Medical Research Unit on Immunochemistry, Specialties Hospital, National Medical Centre "Siglo XXI" Mexican Institute for Social Security, Mexico City, Mexico
| | - Anna E Schager
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, B15 2TT, UK.,Institute of Microbiology and Infection, University of Birmingham, Birmingham, B15 2TT, UK
| | - Jennifer L Marshall
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, B15 2TT, UK
| | - Charlotte N Cook
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, B15 2TT, UK.,Institute of Microbiology and Infection, University of Birmingham, Birmingham, B15 2TT, UK
| | - Saeeda Bobat
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, B15 2TT, UK.,Institute of Microbiology and Infection, University of Birmingham, Birmingham, B15 2TT, UK
| | - Hyea Hwang
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta GA, 30332, USA
| | - Byeong Jae Chun
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta GA, 30332, USA
| | - Erin Logan
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Anzio Road, Cape Town, Western Cape, 7925, South Africa
| | - Jack A Bryant
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, B15 2TT, UK
| | - Will M Channell
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, B15 2TT, UK
| | - Faye C Morris
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, B15 2TT, UK
| | - Sian E Jossi
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, B15 2TT, UK
| | - Areej Alshayea
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, B15 2TT, UK
| | - Amanda E Rossiter
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, B15 2TT, UK
| | - Paul A Barrow
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington, Leicestershire, LE12 5RD, UK
| | - William G Horsnell
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Anzio Road, Cape Town, Western Cape, 7925, South Africa
| | - Calman A MacLennan
- Jenner Institute, Nuffield Department of Medicine, Old Road Campus Research Building, Roosevelt Drive, University of Oxford, Oxford, OX3 7DQ, UK
| | - Ian R Henderson
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, B15 2TT, UK
| | - Jeremy H Lakey
- Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne, NE2 4HH, UK
| | - James C Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Constantino López-Macías
- Medical Research Unit on Immunochemistry, Specialties Hospital, National Medical Centre "Siglo XXI" Mexican Institute for Social Security, Mexico City, Mexico
| | - Vassiliy N Bavro
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK.
| | - Adam F Cunningham
- Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, B15 2TT, UK. .,Institute of Microbiology and Infection, University of Birmingham, Birmingham, B15 2TT, UK.
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11
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Jefferies D, Shearer J, Khalid S. Role of O-Antigen in Response to Mechanical Stress of the E. coli Outer Membrane: Insights from Coarse-Grained MD Simulations. J Phys Chem B 2019; 123:3567-3575. [DOI: 10.1021/acs.jpcb.8b12168] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Damien Jefferies
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
| | - Jonathan Shearer
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
| | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
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12
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Dupuy FG, Pagano I, Andenoro K, Peralta MF, Elhady Y, Heinrich F, Tristram-Nagle S. Selective Interaction of Colistin with Lipid Model Membranes. Biophys J 2019; 114:919-928. [PMID: 29490251 DOI: 10.1016/j.bpj.2017.12.027] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 12/19/2017] [Accepted: 12/21/2017] [Indexed: 11/24/2022] Open
Abstract
Although colistin's clinical use is limited due to its nephrotoxicity, colistin is considered to be an antibiotic of last resort because it is used to treat patients infected with multidrug-resistant bacteria. In an effort to provide molecular details about colistin's ability to kill Gram-negative (G(-)) but not Gram-positive (G(+)) bacteria, we investigated the biophysics of the interaction between colistin and lipid mixtures mimicking the cytoplasmic membrane of G(+), G(-) bacteria as well as eukaryotic cells. Two different models of the G(-) outer membrane (OM) were assayed: lipid A with two deoxy-manno-octulosonyl sugar residues, and Escherichia coli lipopolysaccharide mixed with dilaurylphosphatidylglycerol. We used circular dichroism and x-ray diffuse scattering at low and wide angle in stacked multilayered samples, and neutron reflectivity of single, tethered bilayers mixed with colistin. We found no differences in secondary structure when colistin was bound to G(-) versus G(+) membrane mimics, ruling out a protein conformational change as the cause of this difference. However, bending modulus KC perturbation was quite irregular for the G(-) inner membrane, where colistin produced a softening of the membranes at an intermediate lipid/peptide molar ratio but stiffening at lower and higher peptide concentrations, whereas in G(+) and eukaryotic mimics there was only a slight softening. Acyl chain order in G(-) was perturbed similarly to KC. In G(+), there was only a slight softening and disordering effect, whereas in OM mimics, there was a slight stiffening and ordering of both membranes with increasing colistin. X-ray and neutron reflectivity structural results reveal colistin partitions deepest to reach the hydrocarbon interior in G(-) membranes, but remains in the headgroup region in G(+), OM, and eukaryotic mimics. It is possible that domain formation is responsible for the erratic response of G(-) inner membranes to colistin and for its deeper penetration, which could increase membrane permeability.
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Affiliation(s)
- Fernando G Dupuy
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania; Instituto Superior de Investigaciones Biológicas (INSIBIO) CONICET-UNT and Instituto de Química Biológica "Dr Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, UNT, San Miguel de Tucumán, Argentina
| | - Isabella Pagano
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Kathryn Andenoro
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Maria F Peralta
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania; Instituto de Investigación Médica M y M Ferreyra, CONICET-National University of Córdoba, Córdoba, Argentina
| | - Yasmene Elhady
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Frank Heinrich
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania; National Institute of Standards and Technology Center for Neutron Research, Gaithersburg, Maryland
| | - Stephanie Tristram-Nagle
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, Pennsylvania.
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13
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Khalid S, Piggot TJ, Samsudin F. Atomistic and Coarse Grain Simulations of the Cell Envelope of Gram-Negative Bacteria: What Have We Learned? Acc Chem Res 2019; 52:180-188. [PMID: 30562009 DOI: 10.1021/acs.accounts.8b00377] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Bacterial membranes, and those of Gram-negative bacteria in particular, are some of the most biochemically diverse membranes known. They incorporate a wide range of lipid types and proteins of varying sizes, architectures, and functions. While simpler biological membranes have been the focus of myriad simulation studies over the years that have yielded invaluable details to complement, and often to direct, ongoing experimental studies, simulations of complex bacterial membranes have been slower to emerge. However, the past few years have seen tremendous activity in this area, leading to advances such as the development of atomistic and coarse-grain models of the lipopolysaccharide (LPS) component of the outer membrane that are compatible with widely used simulation codes. In this Account, we review our contributions to the field of molecular simulations of the bacterial cell envelope, including the development of models of both membranes and the cell wall of Gram-negative bacteria, with a predominant focus on E. coli. At the atomistic level, simulations of chemically accurate models of both membranes have revealed the tightly cross-linked nature of the LPS headgroups and have shown that penetration of solutes through these regions is not as straightforward as the route through phospholipids. The energetic differences between the two routes have been calculated. Simulations of native outer membrane proteins in LPS-containing membranes have shown that the conformational dynamics of the proteins is not only slower in LPS but also different compared to in simpler models of phospholipid bilayers. These chemically more complex and consequently biologically more relevant models are leading to details of conformational dynamics that were previously inaccessible from simulations. Coarse-grain models have enabled simulations of multiprotein systems on time scales of microseconds, leading to insights not only into the rates of protein and lipid diffusion but also into the trends in their respective directions of flow. We find that the motions of LPS molecules are highly correlated with each other but also with outer membrane proteins embedded within the membrane. We have shown that the two leaflets of the outer membrane exhibit communication, whereby regions of low disorder in one leaflet correspond to regions of high disorder in the other. The cell wall remains a comparatively neglected component, although models of the E. coli peptidoglycan are now emerging, particularly at the atomistic level. Our simulations of Braun's lipoprotein have shown that bending and tilting of this protein afford a degree of variability in the gap between the cell wall and the OM. The noncovalent interactions with the cell wall of proteins such as OmpA can further influence the width of this gap by extension or contraction of their linker domains. Overall we have shown that the dynamics of proteins, lipids, and other molecular species within the outer membrane cannot be approximated using simpler phospholipid bilayers, if one is addressing questions regarding the in vivo behavior of Gram-negative bacteria. These membranes have their own unique chemical characteristics that cannot be decoupled from their biological functions.
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Affiliation(s)
- Syma Khalid
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
| | - Thomas J Piggot
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
- Chemical Biological and Radiological Sciences, Defence Science and Technology Laboratory, Porton Down, Salisbury, Wiltshire SP4 0JQ, U.K
| | - Firdaus Samsudin
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K
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14
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Li A, Schertzer JW, Yong X. Molecular dynamics modeling of Pseudomonas aeruginosa outer membranes. Phys Chem Chem Phys 2018; 20:23635-23648. [PMID: 30191217 DOI: 10.1039/c8cp04278k] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Pseudomonas aeruginosa is a common Gram-negative bacterium and opportunistic human pathogen. The distinctive structure of its outer membrane (OM) and outer membrane vesicles (OMVs) plays a fundamental role in bacterial virulence, colonization ability, and antibiotic resistance. To provide critical insights into OM and OMV functionality, we conducted an all-atom molecular dynamics study of asymmetric membranes that are biologically relevant to P. aeruginosa. We hybridized a GLYCAM06-based lipopolysaccharides force field with the Stockholm lipids force field (Slipids) to model bilayer membranes with Lipid A molecules in one leaflet and physiologically relevant phospholipid molecules in the other, including 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), 1,2-dipalmitoyl-sn-glycero-3-phosphoglycerol (DPPG), and 1,2-dioleoyl-sn-glycero-3-phosphoglycerol (DOPG). In particular, a membrane with phospholipid composition representing the P. aeruginosa OM was constructed and modeled by mixing the physiologically dominant components. The detailed structure of membranes was characterized by area per lipid, transmembrane mass and charge densities, radial distribution function (RDF), deuterium order parameter (SCD) of acyl chains, and inclination angles of phosphates and disaccharide in Lipid A. The membrane fluidity in equilibrium and the hydration of functional groups were probed and characterized quantitatively. The consistent properties of the Lipid A leaflets in different membranes demonstrate its compatibility with various phospholipids present in the P. aeruginosa OM. The more ordered acyl chains of Lipid A compared to the cytoplasmic cell membrane contribute to the low permeability of bacterial outer membrane. The findings of this computational investigation of P. aeruginosa OM will further the understanding of microbial pathogenesis and enable future study of OMV biogenesis.
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Affiliation(s)
- Ao Li
- Department of Mechanical Engineering, Binghamton University, The State University of New York, Binghamton, New York 13902, USA.
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15
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Saunders GM, Bruce Macdonald HE, Essex JW, Khalid S. Prediction of the Closed Conformation and Insights into the Mechanism of the Membrane Enzyme LpxR. Biophys J 2018; 115:1445-1456. [PMID: 30287112 PMCID: PMC6260217 DOI: 10.1016/j.bpj.2018.09.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Revised: 07/27/2018] [Accepted: 09/06/2018] [Indexed: 01/18/2023] Open
Abstract
Covalent modification of outer membrane lipids of Gram-negative bacteria can impact the ability of the bacterium to develop resistance to antibiotics as well as modulating the immune response of the host. The enzyme LpxR from Salmonella typhimurium is known to deacylate lipopolysaccharide molecules of the outer membrane; however, the mechanism of action is unknown. Here, we employ molecular dynamics and Monte Carlo simulations to study the conformational dynamics and substrate binding of LpxR in representative outer membrane models as well as detergent micelles. We examine the roles of conserved residues and provide an understanding of how LpxR binds its substrate. Our simulations predict that the catalytic H122 must be Nε-protonated for a single water molecule to occupy the space between it and the scissile bond, with a free binding energy of -8.5 kcal mol-1. Furthermore, simulations of the protein within a micelle enable us to predict the structure of the putative "closed" protein. Our results highlight the need for including dynamics, a representative environment, and the consideration of multiple tautomeric and rotameric states of key residues in mechanistic studies; static structures alone do not tell the full story.
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Affiliation(s)
- Graham M Saunders
- Department of Chemistry, University of Southampton, Highfield, Southampton, United Kingdom
| | | | - Jonathan W Essex
- Department of Chemistry, University of Southampton, Highfield, Southampton, United Kingdom
| | - Syma Khalid
- Department of Chemistry, University of Southampton, Highfield, Southampton, United Kingdom.
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16
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Deplazes E. Molecular simulations of venom peptide-membrane interactions: Progress and challenges. Pept Sci (Hoboken) 2018. [DOI: 10.1002/pep2.24060] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Evelyne Deplazes
- School of Pharmacy and Biomedical Sciences; Curtin Health Innovation Research Institute, Curtin Institute for Computation, Curtin University; Bentley, Perth WA 6102 Australia
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17
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Molecular Simulations of Disulfide-Rich Venom Peptides with Ion Channels and Membranes. Molecules 2017; 22:molecules22030362. [PMID: 28264446 PMCID: PMC6155311 DOI: 10.3390/molecules22030362] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 02/23/2017] [Accepted: 02/24/2017] [Indexed: 12/12/2022] Open
Abstract
Disulfide-rich peptides isolated from the venom of arthropods and marine animals are a rich source of potent and selective modulators of ion channels. This makes these peptides valuable lead molecules for the development of new drugs to treat neurological disorders. Consequently, much effort goes into understanding their mechanism of action. This paper presents an overview of how molecular simulations have been used to study the interactions of disulfide-rich venom peptides with ion channels and membranes. The review is focused on the use of docking, molecular dynamics simulations, and free energy calculations to (i) predict the structure of peptide-channel complexes; (ii) calculate binding free energies including the effect of peptide modifications; and (iii) study the membrane-binding properties of disulfide-rich venom peptides. The review concludes with a summary and outlook.
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18
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Pavlova A, Hwang H, Lundquist K, Balusek C, Gumbart JC. Living on the edge: Simulations of bacterial outer-membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1753-9. [PMID: 26826270 DOI: 10.1016/j.bbamem.2016.01.020] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 01/19/2016] [Accepted: 01/20/2016] [Indexed: 01/06/2023]
Abstract
Gram-negative bacteria are distinguished in part by a second, outer membrane surrounding them. This membrane is distinct from others, possessing an outer leaflet composed not of typical phospholipids but rather large, highly charged molecules known as lipopolysaccharides. Therefore, modeling the structure and dynamics of proteins embedded in the outer membrane requires careful consideration of their native environment. In this review, we examine how simulations of such outer-membrane proteins have evolved over the last two decades, culminating most recently in detailed, highly accurate atomistic models of the outer membrane. We also draw attention to how the simulations have coupled with experiments to produce novel insights unattainable through a single approach. This article is part of a Special Issue entitled: Membrane Proteins edited by J.C. Gumbart and Sergei Noskov.
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Affiliation(s)
- Anna Pavlova
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Hyea Hwang
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Karl Lundquist
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - Curtis Balusek
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, United States
| | - James C Gumbart
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, United States.
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19
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Ma H, Irudayanathan FJ, Jiang W, Nangia S. Simulating Gram-Negative Bacterial Outer Membrane: A Coarse Grain Model. J Phys Chem B 2015; 119:14668-82. [DOI: 10.1021/acs.jpcb.5b07122] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Huilin Ma
- Department of Biomedical
and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | | | - Wenjuan Jiang
- Department of Biomedical
and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
| | - Shikha Nangia
- Department of Biomedical
and Chemical Engineering, Syracuse University, Syracuse, New York 13244, United States
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20
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Murzyn K, Pasenkiewicz-Gierula M. Structural Properties of the Water/Membrane Interface of a Bilayer Built of the E. coli Lipid A. J Phys Chem B 2015; 119:5846-56. [DOI: 10.1021/jp5119629] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Krzysztof Murzyn
- Department
of Computational
Biophysics and Bioinformatics, Faculty of Biochemistry,
Biophysics, and Biotechnology, Jagiellonian University, Kraków, Poland
| | - Marta Pasenkiewicz-Gierula
- Department
of Computational
Biophysics and Bioinformatics, Faculty of Biochemistry,
Biophysics, and Biotechnology, Jagiellonian University, Kraków, Poland
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21
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Berglund NA, Piggot TJ, Jefferies D, Sessions RB, Bond PJ, Khalid S. Interaction of the antimicrobial peptide polymyxin B1 with both membranes of E. coli: a molecular dynamics study. PLoS Comput Biol 2015; 11:e1004180. [PMID: 25885324 PMCID: PMC4401565 DOI: 10.1371/journal.pcbi.1004180] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 02/06/2015] [Indexed: 11/17/2022] Open
Abstract
Antimicrobial peptides are small, cationic proteins that can induce lysis of bacterial cells through interaction with their membranes. Different mechanisms for cell lysis have been proposed, but these models tend to neglect the role of the chemical composition of the membrane, which differs between bacterial species and can be heterogeneous even within a single cell. Moreover, the cell envelope of Gram-negative bacteria such as E. coli contains two membranes with differing compositions. To this end, we report the first molecular dynamics simulation study of the interaction of the antimicrobial peptide, polymyxin B1 with complex models of both the inner and outer membranes of E. coli. The results of >16 microseconds of simulation predict that polymyxin B1 is likely to interact with the membranes via distinct mechanisms. The lipopeptides aggregate in the lipopolysaccharide headgroup region of the outer membrane with limited tendency for insertion within the lipid A tails. In contrast, the lipopeptides readily insert into the inner membrane core, and the concomitant increased hydration may be responsible for bilayer destabilization and antimicrobial function. Given the urgent need to develop novel, potent antibiotics, the results presented here reveal key mechanistic details that may be exploited for future rational drug development.
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Affiliation(s)
- Nils A Berglund
- School of Chemistry, University of Southampton, Highfield, Southampton, United Kingdom; Bioinformatics Institute (A*STAR), Singapore
| | - Thomas J Piggot
- School of Chemistry, University of Southampton, Highfield, Southampton, United Kingdom
| | - Damien Jefferies
- School of Chemistry, University of Southampton, Highfield, Southampton, United Kingdom
| | | | - Peter J Bond
- Bioinformatics Institute (A*STAR), Singapore; Department of Biological Sciences, National University of Singapore, Singapore
| | - Syma Khalid
- School of Chemistry, University of Southampton, Highfield, Southampton, United Kingdom
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22
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Anwar MA, Panneerselvam S, Shah M, Choi S. Insights into the species-specific TLR4 signaling mechanism in response to Rhodobacter sphaeroides lipid A detection. Sci Rep 2015; 5:7657. [PMID: 25563849 PMCID: PMC4288214 DOI: 10.1038/srep07657] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 12/03/2014] [Indexed: 11/26/2022] Open
Abstract
TLR4 in complex with MD2 senses the presence of lipid A (LA) and initiates a signaling cascade that curb the infection. This complex is evolutionarily conserved and can initiate the immune system in response to a variety of LAs. In this study, molecular dynamics simulation (25 ns) was performed to elucidate the differential behavior of TLR4/MD2 complex in response to Rhodobacter sphaeroides lipid A (RsLA). Penta-acyl chain-containing RsLA is at the verge of agonist (6 acyl-chains) and antagonist (4 acyl-chains) structure, and activates the TLR4 pathway in horses and hamsters, while inhibiting in humans and murine. In the time-evolved coordinates, the promising factors that dictated the differential response included the local and global mobility pattern of complexes, solvent-accessible surface area of ligand, and surface charge distributions of TLR4 and MD2. We showed that the GlcN1-GlcN2 backbone acquires agonist (3FXI)-like configurations in horses and hamsters, while acquiring antagonist (2E59)-like configurations in humans and murine systems. Moreover, analysis of F126 behavior in the MD2 F126 loop (amino acids 123-129) and loop EF (81-89) suggested that certain sequence variations also contribute to species-specific response. This study underlines the TLR4 signaling mechanism and provides new therapeutic opportunities.
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Affiliation(s)
- Muhammad Ayaz Anwar
- Department of Molecular Science and Technology, Ajou University, Suwon, 443-749, Korea
| | - Suresh Panneerselvam
- Department of Molecular Science and Technology, Ajou University, Suwon, 443-749, Korea
| | - Masaud Shah
- Department of Molecular Science and Technology, Ajou University, Suwon, 443-749, Korea
| | - Sangdun Choi
- Department of Molecular Science and Technology, Ajou University, Suwon, 443-749, Korea
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Dias RP, Lin L, Soares TA, Alexov E. Modeling the electrostatic potential of asymmetric lipopolysaccharide membranes: the MEMPOT algorithm implemented in DelPhi. J Comput Chem 2014; 35:1418-1429. [PMID: 24799021 PMCID: PMC4057312 DOI: 10.1002/jcc.23632] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 04/08/2014] [Accepted: 04/21/2014] [Indexed: 01/10/2023]
Abstract
Four chemotypes of the rough lipopolysaccharides (LPS) membrane from Pseudomonas aeruginosa were investigated by a combined approach of explicit water molecular dynamics (MD) simulations and Poisson-Boltzmann continuum electrostatics with the goal to deliver the distribution of the electrostatic potential across the membrane. For the purpose of this investigation, a new tool for modeling the electrostatic potential profile along the axis normal to the membrane, MEMbrane POTential (MEMPOT), was developed and implemented in DelPhi. Applying MEMPOT on the snapshots obtained by MD simulations, two observations were made: (a) the average electrostatic potential has a complex profile but is mostly positive inside the membrane due to the presence of Ca(2+) ions, which overcompensate for the negative potential created by lipid phosphate groups; and (b) correct modeling of the electrostatic potential profile across the membrane requires taking into account the water phase, while neglecting it (vacuum calculations) results in dramatic changes including a reversal of the sign of the potential inside the membrane. Furthermore, using DelPhi to assign different dielectric constants for different regions of the LPS membranes, it was investigated whether a single frame structure before MD simulations with appropriate dielectric constants for the lipid tails, inner, and the external leaflet regions, can deliver the same average electrostatic potential distribution as obtained from the MD-generated ensemble of structures. Indeed, this can be attained by using smaller dielectric constant for the tail and inner leaflet regions (mostly hydrophobic) than for the external leaflet region (hydrophilic) and the optimal dielectric constant values are chemotype-specific.
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Affiliation(s)
- Roberta P. Dias
- Federal University of Pernambuco, Department of Fundamental Chemistry, Cidade Universitária, Recife, PE 50740-560, Brazil
| | - Lin Lin
- Computational Biophysics and Bioinformatics, Department of Physics, Clemson University, SC 29634, USA
| | - Thereza A. Soares
- Federal University of Pernambuco, Department of Fundamental Chemistry, Cidade Universitária, Recife, PE 50740-560, Brazil
| | - Emil Alexov
- Computational Biophysics and Bioinformatics, Department of Physics, Clemson University, SC 29634, USA
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Dias RP, da Hora GCA, Ramstedt M, Soares TA. Outer Membrane Remodeling: The Structural Dynamics and Electrostatics of Rough Lipopolysaccharide Chemotypes. J Chem Theory Comput 2014; 10:2488-97. [DOI: 10.1021/ct500075h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Roberta P. Dias
- Department
of Fundamental Chemistry, Federal University of Pernambuco, Cidade Universitária, Recife 50740-560, Brazil
| | - Gabriel C. A. da Hora
- Department
of Fundamental Chemistry, Federal University of Pernambuco, Cidade Universitária, Recife 50740-560, Brazil
| | | | - Thereza A. Soares
- Department
of Fundamental Chemistry, Federal University of Pernambuco, Cidade Universitária, Recife 50740-560, Brazil
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25
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Nascimento A, Pontes FJS, Lins RD, Soares TA. Hydration, ionic valence and cross-linking propensities of cations determine the stability of lipopolysaccharide (LPS) membranes. Chem Commun (Camb) 2014; 50:231-3. [DOI: 10.1039/c3cc46918b] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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26
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Garate JA, Oostenbrink C. Lipid A from lipopolysaccharide recognition: structure, dynamics and cooperativity by molecular dynamics simulations. Proteins 2013. [PMID: 23184816 DOI: 10.1002/prot.24223] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Molecular dynamics simulations of Lipid A and its natural precursor Lipid IVA from E.coli have been carried out free in solution, bound to the myeliod differentiation protein 2 (MD2) and in the complex of MD2 with the toll like receptor 4 (TLR4). In addition, simulations of the ligand free MD2 and MD2-TLR4 complex were performed. A structural and energetic characterization of the bound and unbound states of Lipid A/IVA was generated. As the crystal structures depict, the main driving force for MD2-Lipid A/IVA are the hydrophobic interactions between the aliphatic tails and the MD2 cavity. The charged phosphate groups do strongly interact with positively charged residues, located at the surface of MD2. However, they are not essential for keeping the lipids in the cavity, indicating a more prominent role in binding recognition and ionic interactions with TLR4 at the MD2/TLR4 interface. Interestingly, in the absence of any ligand MD2 rapidly closes, blocking the binding cavity. The presence of TLR4, though changing the dynamics, was not able to impede the aforementioned closing event. We hypothesize that fluctuations of the H1 region are essential for this phenomenon, and it is plausible that an equilibrium between the open and closed states exists, although the lengths of our simulations are not sufficient to encompass the reversible process. The MD2/Lipid A-TLR4 complex simulations show that the presence of the ligand energetically stabilizes the complex relative to the ligand-free structures, indicating cooperativity in the binding process.
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Affiliation(s)
- Jose Antonio Garate
- Department of Medical Sciences and Process Engineering, Institute of Molecular Modelling and Simulation, University of Natural Resources and Life Sciences, Vienna, Austria
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27
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Abstract
Complex biological systems are intimately linked to their environment, a very crowded and equally complex solution compartmentalized by fluid membranes. Modeling such systems remains challenging and requires a suitable representation of these solutions and their interfaces. Here, we focus on particle-based modeling at an atomistic level using molecular dynamics (MD) simulations. As an example, we discuss important steps in modeling the solution chemistry of an ion channel of the ligand-gated ion channel receptor family, a major target of many drugs including anesthetics and addiction treatments. The bacterial pentameric ligand-gated ion channel (pLGIC) called GLIC provides clues about the functional importance of solvation, in particular for mechanisms such as permeation and gating. We present some current challenges along with promising novel modeling approaches.
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28
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Kirschner KN, Lins RD, Maass A, Soares TA. A Glycam-Based Force Field for Simulations of Lipopolysaccharide Membranes: Parametrization and Validation. J Chem Theory Comput 2012; 8:4719-31. [DOI: 10.1021/ct300534j] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Karl N. Kirschner
- Fraunhofer-Institute for Algorithms
and Scientific Computing (SCAI), Department of Bioinformatics, Schloss
Birlinghoven, 53754 Sankt Augustin, Germany
| | - Roberto D. Lins
- Department of Fundamental Chemistry,
Federal University of Pernambuco, Cidade Universitária, Recife,
PE 50740-560 Brazil
| | - Astrid Maass
- Fraunhofer-Institute for Algorithms
and Scientific Computing (SCAI), Department of Simulation Engineering,
Schloss Birlinghoven, 53754 Sankt Augustin, Germany
| | - Thereza A. Soares
- Department of Fundamental Chemistry,
Federal University of Pernambuco, Cidade Universitária, Recife,
PE 50740-560 Brazil
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29
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Piggot TJ, Holdbrook DA, Khalid S. Electroporation of the E. coli and S. Aureus Membranes: Molecular Dynamics Simulations of Complex Bacterial Membranes. J Phys Chem B 2011; 115:13381-8. [DOI: 10.1021/jp207013v] [Citation(s) in RCA: 176] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Thomas J. Piggot
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - Daniel A. Holdbrook
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - Syma Khalid
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
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30
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Straatsma T, Bylaska E, van Dam H, Govind N, de Jong W, Kowalski K, Valiev M. Advances in Scalable Computational Chemistry. ACTA ACUST UNITED AC 2011. [DOI: 10.1016/b978-0-444-53835-2.00007-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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31
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One membrane protein, two structures and six environments: a comparative molecular dynamics simulation study of the bacterial outer membrane protein PagP. Mol Membr Biol 2009; 26:205-14. [PMID: 19280380 DOI: 10.1080/09687680902788967] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
PagP is a bacterial outer membrane protein consisting of an 8 stranded transmembrane beta-barrel and an N-terminal alpha-helix. It is an enzyme which catalyses transfer of a palmitoyl chain from a phospholipid to lipid A. Molecular dynamics simulations have been used to compare the dynamic behaviour in simulations starting from two different structures (X-ray vs. NMR) and in six different environments (detergent micelles formed by dodecyl phosphocholine and by octyl glucoside, vs. four species of phospholipid bilayer). Analysis of interactions between the protein and its environment reveals the role played by the N-terminal alpha-helix, which interacts with the lipid headgroups to lock the PagP molecule into the bilayer. The PagP beta-barrel adopts a tilted orientation in lipid bilayers, facilitating access of lipid tails into the mouth of the central binding pocket. In simulations starting from the X-ray structure in lipid bilayer, the L1 and L2 loops move towards one another, leading to the formation of a putative active site by residues H33, D76 and S77 coming closer together.
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32
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Straatsma TP, Soares TA. Characterization of the outer membrane protein OprF of Pseudomonas aeruginosa in a lipopolysaccharide membrane by computer simulation. Proteins 2009; 74:475-88. [PMID: 18655068 DOI: 10.1002/prot.22165] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The N-terminal domain of outer membrane protein OprF of Pseudomonas aeruginosa forms a membrane spanning eight-stranded antiparallel beta-barrel domain that folds into a membrane channel with low conductance. The structure of this protein has been modeled after the crystal structure of the homologous protein OmpA of Escherichia coli. A number of molecular dynamics simulations have been carried out for the homology modeled structure of OprF in an explicit molecular model for the rough lipopolysaccharide (LPS) outer membrane of P. aeruginosa. The structural stability of the outer membrane model as a result of the strong electrostatic interactions compared with simple lipid bilayers is restricting both the conformational flexibility and the lateral diffusion of the porin in the membrane. Constricting side-chain interactions within the pore are similar to those found in reported simulations of the protein in a solvated lipid bilayer membrane. Because of the strong interactions between the loop regions of OprF and functional groups in the saccharide core of the LPS, the entrance to the channel from the extracellular space is widened compared with the lipid bilayer simulations in which the loops are extruding in the solvent. The specific electrostatic signature of the LPS membrane, which results in a net intrinsic dipole across the membrane, is found to be altered by the presence of OprF, resulting in a small electrically positive patch at the position of the channel.
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Affiliation(s)
- T P Straatsma
- Computational Sciences and Mathematics Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
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