1
|
Pirnia A, Maqdisi R, Mittal S, Sener M, Singharoy A. Perspective on Integrative Simulations of Bioenergetic Domains. J Phys Chem B 2024; 128:3302-3319. [PMID: 38562105 DOI: 10.1021/acs.jpcb.3c07335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Bioenergetic processes in cells, such as photosynthesis or respiration, integrate many time and length scales, which makes the simulation of energy conversion with a mere single level of theory impossible. Just like the myriad of experimental techniques required to examine each level of organization, an array of overlapping computational techniques is necessary to model energy conversion. Here, a perspective is presented on recent efforts for modeling bioenergetic phenomena with a focus on molecular dynamics simulations and its variants as a primary method. An overview of the various classical, quantum mechanical, enhanced sampling, coarse-grained, Brownian dynamics, and Monte Carlo methods is presented. Example applications discussed include multiscale simulations of membrane-wide electron transport, rate kinetics of ATP turnover from electrochemical gradients, and finally, integrative modeling of the chromatophore, a photosynthetic pseudo-organelle.
Collapse
Affiliation(s)
- Adam Pirnia
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1004, United States
| | - Ranel Maqdisi
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1004, United States
| | - Sumit Mittal
- VIT Bhopal University, Sehore 466114, Madhya Pradesh, India
| | - Melih Sener
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1004, United States
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Abhishek Singharoy
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1004, United States
| |
Collapse
|
2
|
Mamatkulov K, Zavatski S, Arynbek Y, Esawii HA, Burko A, Bandarenka H, Arzumanyan G. Conformational analysis of lipid membrane mimetics modified with A β42 peptide by Raman spectroscopy and computer simulations. J Biomol Struct Dyn 2024:1-14. [PMID: 38520152 DOI: 10.1080/07391102.2024.2330706] [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: 12/20/2023] [Accepted: 03/08/2024] [Indexed: 03/25/2024]
Abstract
Peptide-lipid interactions play an important role in maintaining the integrity and function of the cell membrane. Even slight changes in these interactions can induce the development of various diseases. Specifically, peptide misfolding and aggregation in the membrane is considered to be one of the triggers of Alzheimer's disease (AD), however its exact mechanism is still unclear. To this end, an increase of amyloid-beta (Aβ) peptide concentration in the human brain is widely accepted to gradually produce cytotoxic Aβ aggregates (plaques). These plaques initiate a sequence of pathogenic events ending up in observable symptoms of dementia. Understanding the mechanism of the Aβ interaction with cells is crucial for early detection and prevention of Alzheimer's disease. Hence, in this work, a comprehensive Raman analysis of the Aβ42 conformational dynamics in water and in liposomes and lipodiscs that mimic the membrane system is presented. The obtained results show that the secondary structure of Aβ42 in liposomes is dominated by the α-helix conformation, which remains stable over time. However, it comes as a surprise to reveal that the lipodisc environment induces the transformation of the Aβ42 secondary structure to a β-turn/random coil. Our Raman spectroscopy findings are supported with molecular dynamics (MD) and density functional theory (DFT) simulations, showing their good agreement.Communicated by Ramaswamy H. Sarma.
Collapse
Affiliation(s)
- Kahramon Mamatkulov
- Laboratory of Neutron Physics, Sector of Raman Spectroscopy, Joint Institute for Nuclear Research, Dubna, Russia
| | - Siarhei Zavatski
- Applied Plasmonics Laboratory, Belarusian State University of Informatics and Radioelectronics, Minsk, Belarus
| | - Yersultan Arynbek
- Laboratory of Neutron Physics, Sector of Raman Spectroscopy, Joint Institute for Nuclear Research, Dubna, Russia
- Faculty of Physics and Technology, al-Farabi, Kazakh National University, Almaty, Kazakhstan
| | - Heba A Esawii
- Laboratory of Neutron Physics, Sector of Raman Spectroscopy, Joint Institute for Nuclear Research, Dubna, Russia
- Biophysics Department, Faculty of Science, Cairo University, Egypt
| | - Aliaksandr Burko
- Applied Plasmonics Laboratory, Belarusian State University of Informatics and Radioelectronics, Minsk, Belarus
| | - Hanna Bandarenka
- Applied Plasmonics Laboratory, Belarusian State University of Informatics and Radioelectronics, Minsk, Belarus
| | - Grigory Arzumanyan
- Laboratory of Neutron Physics, Sector of Raman Spectroscopy, Joint Institute for Nuclear Research, Dubna, Russia
| |
Collapse
|
3
|
Melancon K, Pliushcheuskaya P, Meiler J, Künze G. Targeting ion channels with ultra-large library screening for hit discovery. Front Mol Neurosci 2024; 16:1336004. [PMID: 38249296 PMCID: PMC10796734 DOI: 10.3389/fnmol.2023.1336004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 12/05/2023] [Indexed: 01/23/2024] Open
Abstract
Ion channels play a crucial role in a variety of physiological and pathological processes, making them attractive targets for drug development in diseases such as diabetes, epilepsy, hypertension, cancer, and chronic pain. Despite the importance of ion channels in drug discovery, the vastness of chemical space and the complexity of ion channels pose significant challenges for identifying drug candidates. The use of in silico methods in drug discovery has dramatically reduced the time and cost of drug development and has the potential to revolutionize the field of medicine. Recent advances in computer hardware and software have enabled the screening of ultra-large compound libraries. Integration of different methods at various scales and dimensions is becoming an inevitable trend in drug development. In this review, we provide an overview of current state-of-the-art computational chemistry methodologies for ultra-large compound library screening and their application to ion channel drug discovery research. We discuss the advantages and limitations of various in silico techniques, including virtual screening, molecular mechanics/dynamics simulations, and machine learning-based approaches. We also highlight several successful applications of computational chemistry methodologies in ion channel drug discovery and provide insights into future directions and challenges in this field.
Collapse
Affiliation(s)
- Kortney Melancon
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Center for Structural Biology, Vanderbilt University, Nashville, TN, United States
| | | | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, TN, United States
- Center for Structural Biology, Vanderbilt University, Nashville, TN, United States
- Medical Faculty, Institute for Drug Discovery, Leipzig University, Leipzig, Germany
- Center for Scalable Data Analytics and Artificial Intelligence, Leipzig University, Leipzig, Germany
| | - Georg Künze
- Medical Faculty, Institute for Drug Discovery, Leipzig University, Leipzig, Germany
- Center for Scalable Data Analytics and Artificial Intelligence, Leipzig University, Leipzig, Germany
- Interdisciplinary Center for Bioinformatics, Leipzig University, Leipzig, Germany
| |
Collapse
|
4
|
Ingólfsson H, Bhatia H, Aydin F, Oppelstrup T, López CA, Stanton LG, Carpenter TS, Wong S, Di Natale F, Zhang X, Moon JY, Stanley CB, Chavez JR, Nguyen K, Dharuman G, Burns V, Shrestha R, Goswami D, Gulten G, Van QN, Ramanathan A, Van Essen B, Hengartner NW, Stephen AG, Turbyville T, Bremer PT, Gnanakaran S, Glosli JN, Lightstone FC, Nissley DV, Streitz FH. Machine Learning-Driven Multiscale Modeling: Bridging the Scales with a Next-Generation Simulation Infrastructure. J Chem Theory Comput 2023; 19:2658-2675. [PMID: 37075065 PMCID: PMC10173464 DOI: 10.1021/acs.jctc.2c01018] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Indexed: 04/20/2023]
Abstract
Interdependence across time and length scales is common in biology, where atomic interactions can impact larger-scale phenomenon. Such dependence is especially true for a well-known cancer signaling pathway, where the membrane-bound RAS protein binds an effector protein called RAF. To capture the driving forces that bring RAS and RAF (represented as two domains, RBD and CRD) together on the plasma membrane, simulations with the ability to calculate atomic detail while having long time and large length- scales are needed. The Multiscale Machine-Learned Modeling Infrastructure (MuMMI) is able to resolve RAS/RAF protein-membrane interactions that identify specific lipid-protein fingerprints that enhance protein orientations viable for effector binding. MuMMI is a fully automated, ensemble-based multiscale approach connecting three resolution scales: (1) the coarsest scale is a continuum model able to simulate milliseconds of time for a 1 μm2 membrane, (2) the middle scale is a coarse-grained (CG) Martini bead model to explore protein-lipid interactions, and (3) the finest scale is an all-atom (AA) model capturing specific interactions between lipids and proteins. MuMMI dynamically couples adjacent scales in a pairwise manner using machine learning (ML). The dynamic coupling allows for better sampling of the refined scale from the adjacent coarse scale (forward) and on-the-fly feedback to improve the fidelity of the coarser scale from the adjacent refined scale (backward). MuMMI operates efficiently at any scale, from a few compute nodes to the largest supercomputers in the world, and is generalizable to simulate different systems. As computing resources continue to increase and multiscale methods continue to advance, fully automated multiscale simulations (like MuMMI) will be commonly used to address complex science questions.
Collapse
Affiliation(s)
- Helgi
I. Ingólfsson
- Physical
and Life Sciences (PLS) Directorate, Lawrence
Livermore National Laboratory, Livermore, California 94550, United States
| | - Harsh Bhatia
- Computing
Directorate, Lawrence Livermore National
Laboratory, Livermore, California 94550, United States
| | - Fikret Aydin
- Physical
and Life Sciences (PLS) Directorate, Lawrence
Livermore National Laboratory, Livermore, California 94550, United States
| | - Tomas Oppelstrup
- Physical
and Life Sciences (PLS) Directorate, Lawrence
Livermore National Laboratory, Livermore, California 94550, United States
| | - Cesar A. López
- Theoretical
Biology and Biophysics Group, Los Alamos
National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Liam G. Stanton
- Department
of Mathematics and Statistics, San José
State University, San José, California 95192, United States
| | - Timothy S. Carpenter
- Physical
and Life Sciences (PLS) Directorate, Lawrence
Livermore National Laboratory, Livermore, California 94550, United States
| | - Sergio Wong
- Physical
and Life Sciences (PLS) Directorate, Lawrence
Livermore National Laboratory, Livermore, California 94550, United States
| | - Francesco Di Natale
- Computing
Directorate, Lawrence Livermore National
Laboratory, Livermore, California 94550, United States
| | - Xiaohua Zhang
- Physical
and Life Sciences (PLS) Directorate, Lawrence
Livermore National Laboratory, Livermore, California 94550, United States
| | - Joseph Y. Moon
- Computing
Directorate, Lawrence Livermore National
Laboratory, Livermore, California 94550, United States
| | - Christopher B. Stanley
- Computational
Sciences and Engineering Division, Oak Ridge
National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Joseph R. Chavez
- Computing
Directorate, Lawrence Livermore National
Laboratory, Livermore, California 94550, United States
| | - Kien Nguyen
- Theoretical
Biology and Biophysics Group, Los Alamos
National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Gautham Dharuman
- Physical
and Life Sciences (PLS) Directorate, Lawrence
Livermore National Laboratory, Livermore, California 94550, United States
| | - Violetta Burns
- Theoretical
Biology and Biophysics Group, Los Alamos
National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Rebika Shrestha
- RAS Initiative,
The Cancer Research Technology Program, Frederick National Laboratory, Frederick, Maryland 21701, United States
| | - Debanjan Goswami
- RAS Initiative,
The Cancer Research Technology Program, Frederick National Laboratory, Frederick, Maryland 21701, United States
| | - Gulcin Gulten
- RAS Initiative,
The Cancer Research Technology Program, Frederick National Laboratory, Frederick, Maryland 21701, United States
| | - Que N. Van
- RAS Initiative,
The Cancer Research Technology Program, Frederick National Laboratory, Frederick, Maryland 21701, United States
| | - Arvind Ramanathan
- Computing,
Environment & Life Sciences (CELS) Directorate, Argonne National Laboratory, Lemont, Illinois 60439, United States
| | - Brian Van Essen
- Computing
Directorate, Lawrence Livermore National
Laboratory, Livermore, California 94550, United States
| | - Nicolas W. Hengartner
- Theoretical
Biology and Biophysics Group, Los Alamos
National Laboratory, Los Alamos, New Mexico 87545, United States
| | - Andrew G. Stephen
- RAS Initiative,
The Cancer Research Technology Program, Frederick National Laboratory, Frederick, Maryland 21701, United States
| | - Thomas Turbyville
- RAS Initiative,
The Cancer Research Technology Program, Frederick National Laboratory, Frederick, Maryland 21701, United States
| | - Peer-Timo Bremer
- Computing
Directorate, Lawrence Livermore National
Laboratory, Livermore, California 94550, United States
| | - S. Gnanakaran
- Theoretical
Biology and Biophysics Group, Los Alamos
National Laboratory, Los Alamos, New Mexico 87545, United States
| | - James N. Glosli
- Physical
and Life Sciences (PLS) Directorate, Lawrence
Livermore National Laboratory, Livermore, California 94550, United States
| | - Felice C. Lightstone
- Physical
and Life Sciences (PLS) Directorate, Lawrence
Livermore National Laboratory, Livermore, California 94550, United States
| | - Dwight V. Nissley
- RAS Initiative,
The Cancer Research Technology Program, Frederick National Laboratory, Frederick, Maryland 21701, United States
| | - Frederick H. Streitz
- Physical
and Life Sciences (PLS) Directorate, Lawrence
Livermore National Laboratory, Livermore, California 94550, United States
| |
Collapse
|
5
|
De Rosa A, McGaughey S, Magrath I, Byrt C. Molecular membrane separation: plants inspire new technologies. THE NEW PHYTOLOGIST 2023; 238:33-54. [PMID: 36683439 DOI: 10.1111/nph.18762] [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: 08/07/2022] [Accepted: 01/06/2023] [Indexed: 06/17/2023]
Abstract
Plants draw up their surrounding soil solution to gain water and nutrients required for growth, development and reproduction. Obtaining adequate water and nutrients involves taking up both desired and undesired elements from the soil solution and separating resources from waste. Desirable and undesirable elements in the soil solution can share similar chemical properties, such as size and charge. Plants use membrane separation mechanisms to distinguish between different molecules that have similar chemical properties. Membrane separation enables distribution or retention of resources and efflux or compartmentation of waste. Plants use specialised membrane separation mechanisms to adapt to challenging soil solution compositions and distinguish between resources and waste. Coordination and regulation of these mechanisms between different tissues, cell types and subcellular membranes supports plant nutrition, environmental stress tolerance and energy management. This review considers membrane separation mechanisms in plants that contribute to specialised separation processes and highlights mechanisms of interest for engineering plants with enhanced performance in challenging conditions and for inspiring the development of novel industrial membrane separation technologies. Knowledge gained from studying plant membrane separation mechanisms can be applied to developing precision separation technologies. Separation technologies are needed for harvesting resources from industrial wastes and transitioning to a circular green economy.
Collapse
Affiliation(s)
- Annamaria De Rosa
- Division of Plant Science, Research School of Biology, Australian National University, 2601, ACT, Acton, Australia
| | - Samantha McGaughey
- Division of Plant Science, Research School of Biology, Australian National University, 2601, ACT, Acton, Australia
| | - Isobel Magrath
- Division of Plant Science, Research School of Biology, Australian National University, 2601, ACT, Acton, Australia
| | - Caitlin Byrt
- Division of Plant Science, Research School of Biology, Australian National University, 2601, ACT, Acton, Australia
| |
Collapse
|
6
|
Situ AJ, Kim J, An W, Kim C, Ulmer TS. Insight Into Pathological Integrin αIIbβ3 Activation From Safeguarding The Inactive State. J Mol Biol 2021; 433:166832. [PMID: 33539882 PMCID: PMC11025565 DOI: 10.1016/j.jmb.2021.166832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 01/01/2021] [Accepted: 01/12/2021] [Indexed: 11/20/2022]
Abstract
The inhibition of physiological activation pathways of the platelet adhesion receptor integrin αIIbβ3 may fail to prevent fatal thrombosis, suggesting that the receptor is at risk of activation by yet an unidentified pathway. Here, we report the discovery and characterization of a structural motif that safeguards the receptor by selectively destabilizing its inactive state. At the extracellular membrane border, an overpacked αIIb(W968)-β3(I693) contact prevents αIIb(Gly972) from optimally assembling the αIIbβ3 transmembrane complex, which maintains the inactive state. This destabilization of approximately 1.0 kcal/mol could be mitigated by hydrodynamic forces but not physiological agonists, thereby identifying hydrodynamic forces as pathological activation stimulus. As reproductive life spans are not generally limited by cardiovascular disease, it appears that the evolution of the safeguard was driven by fatal, hydrodynamic force-mediated integrin αIIbβ3 activation in the healthy cardiovascular system. The triggering of the safeguard solely by pathological stimuli achieves an effective increase of the free energy barrier between inactive and active receptor states without incurring an increased risk of bleeding. Thus, integrin αIIbβ3 has evolved an effective way to protect receptor functional states that indicates the availability of a mechanical activation pathway when hydrodynamic forces exceed physiological margins.
Collapse
Affiliation(s)
- Alan J Situ
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Jiyoon Kim
- Department of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Woojin An
- Department of Biochemistry and Molecular Medicine, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA, USA
| | - Chungho Kim
- Department of Life Sciences, Korea University, Seoul, Republic of Korea.
| | - Tobias S Ulmer
- Department of Physiology and Neuroscience, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
| |
Collapse
|
7
|
Esmaile SC, Bezerra KS, de Oliveira Campos DM, da Silva MK, Neto JXL, Manzoni V, Fulco UL, Oliveira JIN. Quantum binding energy features of the drug olmesartan bound to angiotensin type-1 receptors in the therapeutics of stroke. NEW J CHEM 2021. [DOI: 10.1039/d1nj03975j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We investigated the binding energies of 105 residues within a 10 Å pocket radius, predicted the energetic relevance of olmesartan regions, and the influence of individual protein segments on OLM -AT1 binding.
Collapse
Affiliation(s)
- Stephany Campanelli Esmaile
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN, Brazil
| | - Katyanna Sales Bezerra
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN, Brazil
| | | | - Maria Karolaynne da Silva
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN, Brazil
| | - José Xavier Lima Neto
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN, Brazil
| | - Vinicius Manzoni
- Instituto de Física, Universidade Federal de Alagoas, 57072-970, Maceio, AL, Brazil
| | - Umberto Laino Fulco
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN, Brazil
| | - Jonas Ivan Nobre Oliveira
- Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN, Brazil
| |
Collapse
|
8
|
Abstract
Molecular dynamics simulations of membrane proteins have grown dramatically in the last 20 years. Running these simulations first requires embedding the protein's three-dimensional structure in a lipid bilayer of a suitable composition, one that resembles its native environment. This step is far from trivial, especially for modeling heterogeneous mixtures of lipids. CHARMM-GUI, a webserver for simulation system preparation greatly simplifies this step, allowing for the construction of complex heterogeneous and/or asymmetric membranes. Here, we demonstrate how to use CHARMM-GUI to build the membrane for the outer-membrane protein BamA.
Collapse
|
9
|
King GM, Kosztin I. Towards a Quantitative Understanding of Protein-Lipid Bilayer Interactions at the Single Molecule Level: Opportunities and Challenges. J Membr Biol 2020; 254:17-28. [PMID: 33196888 DOI: 10.1007/s00232-020-00151-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 11/04/2020] [Indexed: 11/28/2022]
Abstract
Protein-lipid interfaces are among the most fundamental in biology. Yet applying conventional techniques to study the biophysical attributes of these systems is challenging and has left many unknowns. For example, what is the kinetic pathway and energy landscape experienced by a polypeptide chain when in close proximity to a fluid lipid bilayer? Here we review the experimental and theoretical progress we have made in addressing this question from a single molecule perspective. Some remaining impediments are also discussed.
Collapse
Affiliation(s)
- Gavin M King
- Department of Physics and Astronomy, University of Missouri-Columbia, Columbia, MO, 65211, USA. .,Department of Biochemistry, University of Missouri-Columbia, Columbia, MO, 65211, USA.
| | - Ioan Kosztin
- Department of Physics and Astronomy, University of Missouri-Columbia, Columbia, MO, 65211, USA.
| |
Collapse
|
10
|
Marrink SJ, Corradi V, Souza PC, Ingólfsson HI, Tieleman DP, Sansom MS. Computational Modeling of Realistic Cell Membranes. Chem Rev 2019; 119:6184-6226. [PMID: 30623647 PMCID: PMC6509646 DOI: 10.1021/acs.chemrev.8b00460] [Citation(s) in RCA: 432] [Impact Index Per Article: 86.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 12/15/2022]
Abstract
Cell membranes contain a large variety of lipid types and are crowded with proteins, endowing them with the plasticity needed to fulfill their key roles in cell functioning. The compositional complexity of cellular membranes gives rise to a heterogeneous lateral organization, which is still poorly understood. Computational models, in particular molecular dynamics simulations and related techniques, have provided important insight into the organizational principles of cell membranes over the past decades. Now, we are witnessing a transition from simulations of simpler membrane models to multicomponent systems, culminating in realistic models of an increasing variety of cell types and organelles. Here, we review the state of the art in the field of realistic membrane simulations and discuss the current limitations and challenges ahead.
Collapse
Affiliation(s)
- Siewert J. Marrink
- Groningen
Biomolecular Sciences and Biotechnology Institute & Zernike Institute
for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Valentina Corradi
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Paulo C.T. Souza
- Groningen
Biomolecular Sciences and Biotechnology Institute & Zernike Institute
for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Helgi I. Ingólfsson
- Biosciences
and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - D. Peter Tieleman
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Mark S.P. Sansom
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
| |
Collapse
|
11
|
Ganesan P, Ramalingam R. Investigation of structural stability and functionality of homodimeric gramicidin towards peptide‐based drug: a molecular simulation approach. J Cell Biochem 2018; 120:4903-4911. [DOI: 10.1002/jcb.27765] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 09/06/2018] [Indexed: 12/17/2022]
Affiliation(s)
- Pavithrra Ganesan
- Bioinformatics Lab, Department of Biotechnology, School of Biosciences and Technology Vellore Institute of Technology (VIT) Vellore India
| | - Rajasekaran Ramalingam
- Bioinformatics Lab, Department of Biotechnology, School of Biosciences and Technology Vellore Institute of Technology (VIT) Vellore India
| |
Collapse
|
12
|
Earnest TM, Cole JA, Luthey-Schulten Z. Simulating biological processes: stochastic physics from whole cells to colonies. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2018; 81:052601. [PMID: 29424367 DOI: 10.1088/1361-6633/aaae2c] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The last few decades have revealed the living cell to be a crowded spatially heterogeneous space teeming with biomolecules whose concentrations and activities are governed by intrinsically random forces. It is from this randomness, however, that a vast array of precisely timed and intricately coordinated biological functions emerge that give rise to the complex forms and behaviors we see in the biosphere around us. This seemingly paradoxical nature of life has drawn the interest of an increasing number of physicists, and recent years have seen stochastic modeling grow into a major subdiscipline within biological physics. Here we review some of the major advances that have shaped our understanding of stochasticity in biology. We begin with some historical context, outlining a string of important experimental results that motivated the development of stochastic modeling. We then embark upon a fairly rigorous treatment of the simulation methods that are currently available for the treatment of stochastic biological models, with an eye toward comparing and contrasting their realms of applicability, and the care that must be taken when parameterizing them. Following that, we describe how stochasticity impacts several key biological functions, including transcription, translation, ribosome biogenesis, chromosome replication, and metabolism, before considering how the functions may be coupled into a comprehensive model of a 'minimal cell'. Finally, we close with our expectation for the future of the field, focusing on how mesoscopic stochastic methods may be augmented with atomic-scale molecular modeling approaches in order to understand life across a range of length and time scales.
Collapse
Affiliation(s)
- Tyler M Earnest
- Department of Chemistry, University of Illinois, Urbana, IL, 61801, United States of America. National Center for Supercomputing Applications, University of Illinois, Urbana, IL, 61801, United States of America
| | | | | |
Collapse
|
13
|
Chipot C, Dehez F, Schnell JR, Zitzmann N, Pebay-Peyroula E, Catoire LJ, Miroux B, Kunji ERS, Veglia G, Cross TA, Schanda P. Perturbations of Native Membrane Protein Structure in Alkyl Phosphocholine Detergents: A Critical Assessment of NMR and Biophysical Studies. Chem Rev 2018; 118:3559-3607. [PMID: 29488756 PMCID: PMC5896743 DOI: 10.1021/acs.chemrev.7b00570] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Indexed: 12/25/2022]
Abstract
Membrane proteins perform a host of vital cellular functions. Deciphering the molecular mechanisms whereby they fulfill these functions requires detailed biophysical and structural investigations. Detergents have proven pivotal to extract the protein from its native surroundings. Yet, they provide a milieu that departs significantly from that of the biological membrane, to the extent that the structure, the dynamics, and the interactions of membrane proteins in detergents may considerably vary, as compared to the native environment. Understanding the impact of detergents on membrane proteins is, therefore, crucial to assess the biological relevance of results obtained in detergents. Here, we review the strengths and weaknesses of alkyl phosphocholines (or foscholines), the most widely used detergent in solution-NMR studies of membrane proteins. While this class of detergents is often successful for membrane protein solubilization, a growing list of examples points to destabilizing and denaturing properties, in particular for α-helical membrane proteins. Our comprehensive analysis stresses the importance of stringent controls when working with this class of detergents and when analyzing the structure and dynamics of membrane proteins in alkyl phosphocholine detergents.
Collapse
Affiliation(s)
- Christophe Chipot
- SRSMC, UMR 7019 Université de Lorraine CNRS, Vandoeuvre-les-Nancy F-54500, France
- Laboratoire
International Associé CNRS and University of Illinois at Urbana−Champaign, Vandoeuvre-les-Nancy F-54506, France
- Department
of Physics, University of Illinois at Urbana−Champaign, 1110 West Green Street, Urbana, Illinois 61801, United States
| | - François Dehez
- SRSMC, UMR 7019 Université de Lorraine CNRS, Vandoeuvre-les-Nancy F-54500, France
- Laboratoire
International Associé CNRS and University of Illinois at Urbana−Champaign, Vandoeuvre-les-Nancy F-54506, France
| | - Jason R. Schnell
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Nicole Zitzmann
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | | | - Laurent J. Catoire
- Laboratory
of Biology and Physico-Chemistry of Membrane Proteins, Institut de Biologie Physico-Chimique (IBPC), UMR
7099 CNRS, Paris 75005, France
- University
Paris Diderot, Paris 75005, France
- PSL
Research University, Paris 75005, France
| | - Bruno Miroux
- Laboratory
of Biology and Physico-Chemistry of Membrane Proteins, Institut de Biologie Physico-Chimique (IBPC), UMR
7099 CNRS, Paris 75005, France
- University
Paris Diderot, Paris 75005, France
- PSL
Research University, Paris 75005, France
| | - Edmund R. S. Kunji
- Medical
Research Council Mitochondrial Biology Unit, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Gianluigi Veglia
- Department
of Biochemistry, Molecular Biology, and Biophysics, and Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Timothy A. Cross
- National
High Magnetic Field Laboratory, Florida
State University, Tallahassee, Florida 32310, United States
| | - Paul Schanda
- Université
Grenoble Alpes, CEA, CNRS, IBS, Grenoble F-38000, France
| |
Collapse
|
14
|
Li B, Fooksa M, Heinze S, Meiler J. Finding the needle in the haystack: towards solving the protein-folding problem computationally. Crit Rev Biochem Mol Biol 2018; 53:1-28. [PMID: 28976219 PMCID: PMC6790072 DOI: 10.1080/10409238.2017.1380596] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 08/22/2017] [Accepted: 09/13/2017] [Indexed: 12/22/2022]
Abstract
Prediction of protein tertiary structures from amino acid sequence and understanding the mechanisms of how proteins fold, collectively known as "the protein folding problem," has been a grand challenge in molecular biology for over half a century. Theories have been developed that provide us with an unprecedented understanding of protein folding mechanisms. However, computational simulation of protein folding is still difficult, and prediction of protein tertiary structure from amino acid sequence is an unsolved problem. Progress toward a satisfying solution has been slow due to challenges in sampling the vast conformational space and deriving sufficiently accurate energy functions. Nevertheless, several techniques and algorithms have been adopted to overcome these challenges, and the last two decades have seen exciting advances in enhanced sampling algorithms, computational power and tertiary structure prediction methodologies. This review aims at summarizing these computational techniques, specifically conformational sampling algorithms and energy approximations that have been frequently used to study protein-folding mechanisms or to de novo predict protein tertiary structures. We hope that this review can serve as an overview on how the protein-folding problem can be studied computationally and, in cases where experimental approaches are prohibitive, help the researcher choose the most relevant computational approach for the problem at hand. We conclude with a summary of current challenges faced and an outlook on potential future directions.
Collapse
Affiliation(s)
- Bian Li
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Michaela Fooksa
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
- Chemical and Physical Biology Graduate Program, Vanderbilt University, Nashville, TN, USA
| | - Sten Heinze
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Jens Meiler
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| |
Collapse
|
15
|
Reid KA, Davis CM, Dyer RB, Kindt JT. Binding, folding and insertion of a β-hairpin peptide at a lipid bilayer surface: Influence of electrostatics and lipid tail packing. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1860:792-800. [PMID: 29291379 DOI: 10.1016/j.bbamem.2017.12.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 12/12/2017] [Accepted: 12/25/2017] [Indexed: 12/11/2022]
Abstract
Antimicrobial peptides (AMPs) act as host defenses against microbial pathogens. Here we investigate the interactions of SVS-1 (KVKVKVKVdPlPTKVKVKVK), an engineered AMP and anti-cancer β-hairpin peptide, with lipid bilayers using spectroscopic studies and atomistic molecular dynamics simulations. In agreement with literature reports, simulation and experiment show preferential binding of SVS-1 peptides to anionic over neutral bilayers. Fluorescence and circular dichroism studies of a Trp-substituted SVS-1 analogue indicate, however, that it will bind to a zwitterionic DPPC bilayer under high-curvature conditions and folds into a hairpin. In bilayers formed from a 1:1 mixture of DPPC and anionic DPPG lipids, curvature and lipid fluidity are also observed to promote deeper insertion of the fluorescent peptide. Simulations using the CHARMM C36m force field offer complementary insight into timescales and mechanisms of folding and insertion. SVS-1 simulated at an anionic mixed POPC/POPG bilayer folded into a hairpin over a microsecond, the final stage in folding coinciding with the establishment of contact between the peptide's valine sidechains and the lipid tails through a "flip and dip" mechanism. Partial, transient folding and superficial bilayer contact are seen in simulation of the peptide at a zwitterionic POPC bilayer. Only when external surface tension is applied does the peptide establish lasting contact with the POPC bilayer. Our findings reveal the influence of disruption to lipid headgroup packing (via curvature or surface tension) on the pathway of binding and insertion, highlighting the collaborative effort of electrostatic and hydrophobic interactions on interaction of SVS-1 with lipid bilayers.
Collapse
Affiliation(s)
- Keon A Reid
- Department of Chemistry, Emory University, 201 Dowman Drive, Atlanta, GA 30322, United States
| | - Caitlin M Davis
- Department of Chemistry, Emory University, 201 Dowman Drive, Atlanta, GA 30322, United States; Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States
| | - R Brian Dyer
- Department of Chemistry, Emory University, 201 Dowman Drive, Atlanta, GA 30322, United States
| | - James T Kindt
- Department of Chemistry, Emory University, 201 Dowman Drive, Atlanta, GA 30322, United States.
| |
Collapse
|
16
|
Singh A, Vanga SK, Orsat V, Raghavan V. Application of molecular dynamic simulation to study food proteins: A review. Crit Rev Food Sci Nutr 2017; 58:2779-2789. [DOI: 10.1080/10408398.2017.1341864] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Ashutosh Singh
- School of Engineering, University of Guelph, Guelph, Ontario, Canada
| | - Sai Kranthi Vanga
- Faculty of Agriculture and Environmental Studies, Department of Bioresource Engineering, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Valerie Orsat
- Faculty of Agriculture and Environmental Studies, Department of Bioresource Engineering, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| | - Vijaya Raghavan
- Faculty of Agriculture and Environmental Studies, Department of Bioresource Engineering, McGill University, Sainte-Anne-de-Bellevue, QC, Canada
| |
Collapse
|
17
|
Huber RG, Marzinek JK, Holdbrook DA, Bond PJ. Multiscale molecular dynamics simulation approaches to the structure and dynamics of viruses. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 128:121-132. [DOI: 10.1016/j.pbiomolbio.2016.09.010] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 09/06/2016] [Accepted: 09/27/2016] [Indexed: 12/15/2022]
|
18
|
Interactions stabilizing the C-terminal helix of human phospholipid scramblase 1 in lipid bilayers: A computational study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1200-1210. [DOI: 10.1016/j.bbamem.2017.03.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 03/09/2017] [Accepted: 03/29/2017] [Indexed: 12/19/2022]
|
19
|
Chai M, Liu B, Sun F, Wei P, Chen P, Xu L, Luo SZ. Insights into the transmembrane helix associations of kit ligand by molecular dynamics simulation and TOXCAT. Proteins 2017; 85:1362-1370. [DOI: 10.1002/prot.25297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Revised: 02/18/2017] [Accepted: 03/27/2017] [Indexed: 12/24/2022]
Affiliation(s)
- Mengya Chai
- Beijing Key Laboratory of Bioprocess College of Life Science and Technology; Beijing, University of Chemical Technology; Beijing 100029 China
| | - Bo Liu
- Beijing Key Laboratory of Bioprocess College of Life Science and Technology; Beijing, University of Chemical Technology; Beijing 100029 China
| | - Fude Sun
- Beijing Key Laboratory of Bioprocess College of Life Science and Technology; Beijing, University of Chemical Technology; Beijing 100029 China
| | - Peng Wei
- Beijing Key Laboratory of Bioprocess College of Life Science and Technology; Beijing, University of Chemical Technology; Beijing 100029 China
- School of Basic Medical Science; Beijing University of Chinese Medicine; Beijing 100029 China
| | - Peng Chen
- Beijing Key Laboratory of Bioprocess College of Life Science and Technology; Beijing, University of Chemical Technology; Beijing 100029 China
| | - Lida Xu
- Beijing Key Laboratory of Bioprocess College of Life Science and Technology; Beijing, University of Chemical Technology; Beijing 100029 China
| | - Shi-Zhong Luo
- Beijing Key Laboratory of Bioprocess College of Life Science and Technology; Beijing, University of Chemical Technology; Beijing 100029 China
| |
Collapse
|
20
|
Yelshanskaya MV, Mesbahi-Vasey S, Kurnikova MG, Sobolevsky AI. Role of the Ion Channel Extracellular Collar in AMPA Receptor Gating. Sci Rep 2017; 7:1050. [PMID: 28432359 PMCID: PMC5430913 DOI: 10.1038/s41598-017-01146-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 03/21/2017] [Indexed: 11/09/2022] Open
Abstract
AMPA subtype ionotropic glutamate receptors mediate fast excitatory neurotransmission and are implicated in numerous neurological diseases. Ionic currents through AMPA receptor channels can be allosterically regulated via different sites on the receptor protein. We used site-directed mutagenesis and patch-clamp recordings to probe the ion channel extracellular collar, the binding region for noncompetitive allosteric inhibitors. We found position and substitution-dependent effects for introduced mutations at this region on AMPA receptor gating. The results of mutagenesis suggested that the transmembrane domains M1, M3 and M4, which contribute to the ion channel extracellular collar, undergo significant relative displacement during gating. We used molecular dynamics simulations to predict an AMPA receptor open state structure and rationalize the results of mutagenesis. We conclude that the ion channel extracellular collar plays a distinct role in gating and represents a hub for powerful allosteric modulation of AMPA receptor function that can be used for developing novel therapeutics.
Collapse
Affiliation(s)
- Maria V Yelshanskaya
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY, 10032, USA
| | - Samaneh Mesbahi-Vasey
- Chemistry Department, Carnegie Mellon University, 4400 Fifth Ave, Pittsburgh, PA, 15213, USA
| | - Maria G Kurnikova
- Chemistry Department, Carnegie Mellon University, 4400 Fifth Ave, Pittsburgh, PA, 15213, USA.
| | - Alexander I Sobolevsky
- Department of Biochemistry and Molecular Biophysics, Columbia University, 650 West 168th Street, New York, NY, 10032, USA.
| |
Collapse
|
21
|
Kamiya M, Hayashi S. Photoactivation Intermediates of a G-Protein Coupled Receptor Rhodopsin Investigated by a Hybrid Molecular Simulation. J Phys Chem B 2017; 121:3842-3852. [PMID: 28240904 DOI: 10.1021/acs.jpcb.6b13050] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Rhodopsin is a G-protein coupled receptor functioning as a photoreceptor for vision through photoactivation of a covalently bound ligand of a retinal protonated Schiff base chromophore. Despite the availability of structural information on the inactivated and activated forms of the receptor, the transition processes initiated by the photoabsorption have not been well understood. Here we theoretically examined the photoactivation processes by means of molecular dynamics (MD) simulations and ab initio quantum mechanical/molecular mechanical (QM/MM) free energy geometry optimizations which enabled accurate geometry determination of the ligand molecule in ample statistical conformational samples of the protein. Structures of the intermediate states of the activation process, blue-shifted intermediate and Lumi, as well as the dark state first generated by MD simulations and then refined by the QM/MM free energy geometry optimizations were characterized by large displacement of the β-ionone ring of retinal along with change in the hydrogen bond of the protonated Schiff base. The ab initio calculations of vibrational and electronic spectroscopic properties of those states well reproduced the experimental observations and successfully identified the molecular origins underlying the spectroscopic features. The structural evolution in the formation of the intermediates provides a molecular insight into the efficient activation processes of the receptor.
Collapse
Affiliation(s)
- Motoshi Kamiya
- Department of Chemistry, Graduate School of Science, Kyoto University , Kyoto 606-8502, Japan
| | - Shigehiko Hayashi
- Department of Chemistry, Graduate School of Science, Kyoto University , Kyoto 606-8502, Japan
| |
Collapse
|
22
|
Maingi V, Burns JR, Uusitalo JJ, Howorka S, Marrink SJ, Sansom MSP. Stability and dynamics of membrane-spanning DNA nanopores. Nat Commun 2017; 8:14784. [PMID: 28317903 PMCID: PMC5364398 DOI: 10.1038/ncomms14784] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 01/31/2017] [Indexed: 01/05/2023] Open
Abstract
Recently developed DNA-based analogues of membrane proteins have advanced synthetic biology. A fundamental question is how hydrophilic nanostructures reside in the hydrophobic environment of the membrane. Here, we use multiscale molecular dynamics (MD) simulations to explore the structure, stability and dynamics of an archetypical DNA nanotube inserted via a ring of membrane anchors into a phospholipid bilayer. Coarse-grained MD reveals that the lipids reorganize locally to interact closely with the membrane-spanning section of the DNA tube. Steered simulations along the bilayer normal establish the metastable nature of the inserted pore, yielding a force profile with barriers for membrane exit due to the membrane anchors. Atomistic, equilibrium simulations at two salt concentrations confirm the close packing of lipid around of the stably inserted DNA pore and its cation selectivity, while revealing localized structural fluctuations. The wide-ranging and detailed insight informs the design of next-generation DNA pores for synthetic biology or biomedicine. Although DNA nanopores are widely explored as synthetic membrane proteins, it is still unclear how the anionic DNA assemblies stably reside within the hydrophobic core of a lipid bilayer. Here, the authors use molecular dynamics simulations to reveal the key dynamic interactions and energetics stabilizing the nanopore-membrane interaction.
Collapse
Affiliation(s)
- Vishal Maingi
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Jonathan R Burns
- Department of Chemistry, Institute of Structural Molecular Biology, University College London, London WC1H 0AJ, UK
| | - Jaakko J Uusitalo
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Stefan Howorka
- Department of Chemistry, Institute of Structural Molecular Biology, University College London, London WC1H 0AJ, UK
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| |
Collapse
|
23
|
Kitjaruwankul S, Khrutto C, Sompornpisut P, Farmer BL, Pandey RB. Asymmetry in structural response of inner and outer transmembrane segments of CorA protein by a coarse-grain model. J Chem Phys 2016; 145:135101. [PMID: 27782431 DOI: 10.1063/1.4963807] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Structure of CorA protein and its inner (i.corA) and outer (o.corA) transmembrane (TM) components are investigated as a function of temperature by a coarse-grained Monte Carlo simulation. Thermal response of i.corA is found to differ considerably from that of the outer component, o.corA. Analysis of the radius of gyration reveals that the inner TM component undergoes a continuous transition from a globular conformation to a random coil structure on raising the temperature. In contrast, the outer transmembrane component exhibits an abrupt (nearly discontinuous) thermal response in a narrow range of temperature. Scaling of the structure factor shows a globular structure of i.corA at a low temperature with an effective dimension D ∼ 3 and a random coil at a high temperature with D ∼ 2. The residue distribution in o.corA is slightly sparser than that of i.corA in a narrow thermos-responsive regime. The difference in thermos-response characteristics of these components (i.corA and o.corA) may reflect their unique transmembrane functions.
Collapse
Affiliation(s)
- Sunan Kitjaruwankul
- Faculty of Science at Sriracha, Kasetsart University Sriracha Campus, Chonburi 20230, Thailand
| | - Channarong Khrutto
- Department of Chemistry, Chulalongkorn University, Bangkok 10330, Thailand
| | | | - B L Farmer
- Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright Patterson, Air Force Base, Ohio 45433, USA
| | - R B Pandey
- Department of Physics and Astronomy, University of Southern Mississippi, Hattiesburg, Mississippi 39406, USA
| |
Collapse
|
24
|
Structure and dynamics of a free aquaporin (AQP1) by a coarse-grained Monte Carlo simulation. Struct Chem 2016. [DOI: 10.1007/s11224-016-0836-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
|
25
|
Parkin J, Chavent M, Khalid S. Molecular Simulations of Gram-Negative Bacterial Membranes: A Vignette of Some Recent Successes. Biophys J 2016; 109:461-8. [PMID: 26244728 DOI: 10.1016/j.bpj.2015.06.050] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 06/09/2015] [Accepted: 06/24/2015] [Indexed: 01/05/2023] Open
Abstract
In the following review we use recent examples from the literature to discuss progress in the area of atomistic and coarse-grained molecular dynamics simulations of selected bacterial membranes and proteins, with a particular focus on Gram-negative bacteria. As structural biology continues to provide increasingly high-resolution data on the proteins that reside within these membranes, simulations have an important role to play in linking these data with the dynamical behavior and function of these proteins. In particular, in the last few years there has been significant progress in addressing the issue of biochemical complexity of bacterial membranes such that the heterogeneity of the lipid and protein components of these membranes are now being incorporated into molecular-level models. Thus, in future we can look forward to complementary data from structural biology and molecular simulations combining to provide key details of structure-dynamics-function relationships in bacterial membranes.
Collapse
Affiliation(s)
- Jamie Parkin
- School of Chemistry, University of Southampton, Southampton, UK
| | | | - Syma Khalid
- School of Chemistry, University of Southampton, Southampton, UK.
| |
Collapse
|
26
|
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.
Collapse
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.
| |
Collapse
|
27
|
Postic G, Ghouzam Y, Guiraud V, Gelly JC. Membrane positioning for high- and low-resolution protein structures through a binary classification approach. Protein Eng Des Sel 2015; 29:87-91. [PMID: 26685702 DOI: 10.1093/protein/gzv063] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 11/08/2015] [Indexed: 11/13/2022] Open
Abstract
The critical importance of algorithms for orienting proteins in the lipid bilayer stems from the extreme difficulty in obtaining experimental data about the membrane boundaries. Here, we present a computational method for positioning protein structures in the membrane, based on the sole alpha carbon coordinates and, therefore, compatible with both high and low structural resolutions. Our algorithm follows a new and simple approach, by treating the membrane assignment problem as a binary classification. Compared with the state-of-the-art algorithms, our method achieves similar accuracy, while being faster. Finally, our open-source software is also capable of processing coarse-grained models of protein structures.
Collapse
Affiliation(s)
- Guillaume Postic
- Inserm U1134, Paris, France Univ. Paris Diderot, Sorbonne Paris Cité, UMR_S 1134, Paris, France Institut National de la Transfusion Sanguine, Paris, France Laboratory of Excellence GR-Ex, Paris, France
| | - Yassine Ghouzam
- Inserm U1134, Paris, France Univ. Paris Diderot, Sorbonne Paris Cité, UMR_S 1134, Paris, France Institut National de la Transfusion Sanguine, Paris, France Laboratory of Excellence GR-Ex, Paris, France
| | - Vincent Guiraud
- Inserm U1134, Paris, France Univ. Paris Diderot, Sorbonne Paris Cité, UMR_S 1134, Paris, France Institut National de la Transfusion Sanguine, Paris, France Laboratory of Excellence GR-Ex, Paris, France
| | - Jean-Christophe Gelly
- Inserm U1134, Paris, France Univ. Paris Diderot, Sorbonne Paris Cité, UMR_S 1134, Paris, France Institut National de la Transfusion Sanguine, Paris, France Laboratory of Excellence GR-Ex, Paris, France
| |
Collapse
|
28
|
Bud-neck scaffolding as a possible driving force in ESCRT-induced membrane budding. Biophys J 2015; 108:833-843. [PMID: 25692588 PMCID: PMC4336374 DOI: 10.1016/j.bpj.2014.12.040] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 12/20/2014] [Accepted: 12/23/2014] [Indexed: 01/03/2023] Open
Abstract
Membrane budding is essential for processes such as protein sorting and transport. Recent experimental results with ESCRT proteins reveal a novel budding mechanism, with proteins emerging in bud necks but separated from the entire bud surface. Using an elastic model, we show that ESCRT protein shapes are sufficient to spontaneously create experimentally observed structures, with protein-membrane interactions leading to protein scaffolds in bud-neck regions. Furthermore, the model reproduces experimentally observed budding directions and bud sizes. Finally, our results reveal that membrane-mediated sorting has the capability of creating structures more complicated than previously assumed.
Collapse
|
29
|
Molecular Dynamics Simulation of the Effect of Angle Variation on Water Permeability through Hourglass-Shaped Nanopores. MATERIALS 2015; 8:7257-7268. [PMID: 28793636 PMCID: PMC5458919 DOI: 10.3390/ma8115380] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 10/23/2015] [Indexed: 12/29/2022]
Abstract
Water transport through aquaporin water channels occurs extensively in cell membranes. Hourglass-shaped (biconical) pores resemble the geometry of these aquaporin channels and therefore attract much research attention. We assumed that hourglass-shaped nanopores are capable of high water permeation like biological aquaporins. In order to prove the assumption, we investigated nanoscale water transport through a model hourglass-shaped pore using molecular dynamics simulations while varying the angle of the conical entrance and the total nanopore length. The results show that a minimal departure from optimized cone angle (e.g., 9° for 30 Å case) significantly increases the osmotic permeability and that there is a non-linear relationship between permeability and the cone angle. The analysis of hydrodynamic resistance proves that the conical entrance helps to reduce the hydrodynamic entrance hindrance. Our numerical and analytical results thus confirm our initial assumption and suggest that fast water transport can be achieved by adjusting the cone angle and length of an hourglass-shaped nanopore.
Collapse
|
30
|
Leftin A, Molugu TR, Job C, Beyer K, Brown MF. Area per lipid and cholesterol interactions in membranes from separated local-field (13)C NMR spectroscopy. Biophys J 2015; 107:2274-86. [PMID: 25418296 DOI: 10.1016/j.bpj.2014.07.044] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 06/24/2014] [Accepted: 07/15/2014] [Indexed: 10/24/2022] Open
Abstract
Investigations of lipid membranes using NMR spectroscopy generally require isotopic labeling, often precluding structural studies of complex lipid systems. Solid-state (13)C magic-angle spinning NMR spectroscopy at natural isotopic abundance gives site-specific structural information that can aid in the characterization of complex biomembranes. Using the separated local-field experiment DROSS, we resolved (13)C-(1)H residual dipolar couplings that were interpreted with a statistical mean-torque model. Liquid-disordered and liquid-ordered phases were characterized according to membrane thickness and average cross-sectional area per lipid. Knowledge of such structural parameters is vital for molecular dynamics simulations, and provides information about the balance of forces in membrane lipid bilayers. Experiments were conducted with both phosphatidylcholine (dimyristoylphosphatidylcholine (DMPC) and palmitoyloleoylphosphatidylcholine (POPC)) and egg-yolk sphingomyelin (EYSM) lipids, and allowed us to extract segmental order parameters from the (13)C-(1)H residual dipolar couplings. Order parameters were used to calculate membrane structural quantities, including the area per lipid and bilayer thickness. Relative to POPC, EYSM is more ordered in the ld phase and experiences less structural perturbation upon adding 50% cholesterol to form the lo phase. The loss of configurational entropy is smaller for EYSM than for POPC, thus favoring its interaction with cholesterol in raftlike lipid systems. Our studies show that solid-state (13)C NMR spectroscopy is applicable to investigations of complex lipids and makes it possible to obtain structural parameters for biomembrane systems where isotope labeling may be prohibitive.
Collapse
Affiliation(s)
- Avigdor Leftin
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Trivikram R Molugu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Constantin Job
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Klaus Beyer
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona; Department of Physics, University of Arizona, Tucson, Arizona.
| |
Collapse
|
31
|
Jefferys E, Sands ZA, Shi J, Sansom MS, Fowler PW. Alchembed: A Computational Method for Incorporating Multiple Proteins into Complex Lipid Geometries. J Chem Theory Comput 2015; 11:2743-2754. [PMID: 26089745 PMCID: PMC4467903 DOI: 10.1021/ct501111d] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Indexed: 02/06/2023]
Abstract
A necessary step prior to starting any membrane protein computer simulation is the creation of a well-packed configuration of protein(s) and lipids. Here, we demonstrate a method, alchembed, that can simultaneously and rapidly embed multiple proteins into arrangements of lipids described using either atomistic or coarse-grained force fields. During a short simulation, the interactions between the protein(s) and lipids are gradually switched on using a soft-core van der Waals potential. We validate the method on a range of membrane proteins and determine the optimal soft-core parameters required to insert membrane proteins. Since all of the major biomolecular codes include soft-core van der Waals potentials, no additional code is required to apply this method. A tutorial is included in the Supporting Information.
Collapse
Affiliation(s)
- Elizabeth Jefferys
- Department
of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Zara A. Sands
- UCB
NewMedicines, Chemin
du Foriest, 1420 Braine-l’Alleud, Belgium
| | - Jiye Shi
- UCB
NewMedicines, Chemin
du Foriest, 1420 Braine-l’Alleud, Belgium
| | - Mark S.
P. Sansom
- Department
of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Philip W. Fowler
- Department
of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| |
Collapse
|
32
|
Debnath A, Schäfer LV. Structure and Dynamics of Phospholipid Nanodiscs from All-Atom and Coarse-Grained Simulations. J Phys Chem B 2015; 119:6991-7002. [PMID: 25978497 DOI: 10.1021/acs.jpcb.5b02101] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We investigated structural and dynamical properties of nanodiscs comprising dimyristoylphosphatidylcholine (DMPC) lipids and major scaffold protein MSP1Δ(1-22) from human apolipoprotein A-1 using combined all-atom and coarse-grained (CG) molecular dynamics (MD) simulations. The computational efficiency of the Martini-CG force field enables the spontaneous self-assembly of lipids and scaffold proteins into stable nanodisc structures on time scales up to tens of microseconds. Subsequent all-atom and CG-MD simulations reveal that the lipids in the nanodisc have lower configurational entropy and higher acyl tail order than in a lamellar bilayer phase. These altered average properties arise from rather differential behavior of lipids, depending on their location in the nanodisc. Since the scaffold proteins exert constrictive forces from the outer rim of the disc toward its center, lipids at the center of the nanodisc are highly ordered, whereas annular lipids that are in contact with the MSP proteins are remarkably disordered due to perturbed packing. Although specific differences between all-atom and CG simulations are also evident, the results obtained at both levels of resolution are in overall good agreement with each other and provide atomic level interpretations of recent experiments. Thus, the present study highlights the applicability of multiscale simulation approaches for nanodisc systems and opens the way for future applications, including the study of nanodisc-embedded membrane proteins.
Collapse
Affiliation(s)
- Ananya Debnath
- †Department of Chemistry, Indian Institute of Technology Jodhpur, Jodhpur 342 011, India
| | - Lars V Schäfer
- ‡Lehrstuhl für Theoretische Chemie, Ruhr-University Bochum, D-44780 Bochum, Germany
| |
Collapse
|
33
|
Schmidt T, Suk JE, Ye F, Situ AJ, Mazumder P, Ginsberg MH, Ulmer TS. Annular anionic lipids stabilize the integrin αIIbβ3 transmembrane complex. J Biol Chem 2015; 290:8283-93. [PMID: 25632962 DOI: 10.1074/jbc.m114.623504] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cationic membrane-proximal amino acids determine the topology of membrane proteins by interacting with anionic lipids that are restricted to the intracellular membrane leaflet. This mechanism implies that anionic lipids interfere with electrostatic interactions of membrane proteins. The integrin αIIbβ3 transmembrane (TM) complex is stabilized by a membrane-proximal αIIb(Arg(995))-β3(Asp(723)) interaction; here, we examine the influence of anionic lipids on this complex. Anionic lipids compete for αIIb(Arg(995)) contacts with β3(Asp(723)) but paradoxically do not diminish the contribution of αIIb(Arg(995))-β3(Asp(723)) to TM complex stability. Overall, anionic lipids in annular positions stabilize the αIIbβ3 TM complex by up to 0.50 ± 0.02 kcal/mol relative to zwitterionic lipids in a headgroup structure-dependent manner. Comparatively, integrin receptor activation requires TM complex destabilization of 1.5 ± 0.2 kcal/mol, revealing a sizeable influence of lipid composition on TM complex stability. We implicate changes in lipid headgroup accessibility to small molecules (physical membrane characteristics) and specific but dynamic protein-lipid contacts in this TM helix-helix stabilization. Thus, anionic lipids in ubiquitous annular positions can benefit the stability of membrane proteins while leaving membrane-proximal electrostatic interactions intact.
Collapse
Affiliation(s)
- Thomas Schmidt
- From the Department of Biochemistry & Molecular Biology and Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033 and
| | - Jae-Eun Suk
- From the Department of Biochemistry & Molecular Biology and Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033 and
| | - Feng Ye
- the Department of Medicine, University of California San Diego, La Jolla, California 92093
| | - Alan J Situ
- From the Department of Biochemistry & Molecular Biology and Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033 and
| | - Parichita Mazumder
- From the Department of Biochemistry & Molecular Biology and Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033 and
| | - Mark H Ginsberg
- the Department of Medicine, University of California San Diego, La Jolla, California 92093
| | - Tobias S Ulmer
- From the Department of Biochemistry & Molecular Biology and Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90033 and
| |
Collapse
|
34
|
Abstract
Membrane protein structures are underrepresented in the Protein Data Bank (PDB) due to difficulties associated with expression and crystallization. As such, it is one area where computational studies, particularly Molecular Dynamics (MD) simulations, can provide useful additional information. Recently, there has been substantial progress in the simulation of lipid bilayers and membrane proteins embedded within them. Initial efforts at simulating membrane proteins embedded within a lipid bilayer were relatively slow and interactive processes, but recent advances now mean that the setup and running of membrane protein simulations is somewhat more straightforward, though not without its problems. In this chapter, we outline practical methods for setting up and running MD simulations of a membrane protein embedded within a lipid bilayer and discuss methodologies that are likely to contribute future improvements.
Collapse
|
35
|
Jo S, Wu EL, Stuhlsatz D, Klauda JB, Widmalm G, Im W. Lipopolysaccharide membrane building and simulation. Methods Mol Biol 2015; 1273:391-406. [PMID: 25753722 PMCID: PMC4484582 DOI: 10.1007/978-1-4939-2343-4_24] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
While membrane simulations are widely employed to study the structure and dynamics of various lipid bilayers and membrane proteins in the bilayers, simulations of lipopolysaccharides (LPS) in membrane environments have been limited due to their structural complexity, difficulties in building LPS-membrane systems, and lack of the appropriate molecular force fields. In this work, as a first step to extend CHARMM-GUI Membrane Builder to incorporate LPS molecules and to explore their structures and dynamics in membrane environments using molecular dynamics simulations, we describe step-by-step procedures to build LPS bilayer systems using CHARMM and the recently developed CHARMM carbohydrate and lipid force fields. Such procedures are illustrated by building various bilayers of Escherichia coli R1.O6 LPS and the presentation of preliminary simulation results in terms of per-LPS area and density distributions of various components along the membrane normal.
Collapse
Affiliation(s)
- Sunhwan Jo
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, 2030 Becker Drive Lawrence, KS 66045, USA
| | - Emilia L. Wu
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, 2030 Becker Drive Lawrence, KS 66045, USA
| | - Danielle Stuhlsatz
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, 2030 Becker Drive Lawrence, KS 66045, USA
| | - Jeffery B. Klauda
- Department of Chemical and Biomolecular Engineering, The University of Maryland, 2113 Chemical and Nuclear Engineering, College Park, MD 20742, USA
| | - Göran Widmalm
- Department of Organic Chemistry and Stockholm Center for Biomembrane Research, Arrhenius Laboratory, Stockholm University, S106-91 Stockholm, Sweden
| | - Wonpil Im
- Department of Molecular Biosciences and Center for Bioinformatics, The University of Kansas, 2030 Becker Drive Lawrence, KS 66045, USA
| |
Collapse
|
36
|
Kinnun JJ, Mallikarjunaiah KJ, Petrache HI, Brown MF. Elastic deformation and area per lipid of membranes: atomistic view from solid-state deuterium NMR spectroscopy. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1848:246-59. [PMID: 24946141 DOI: 10.1016/j.bbamem.2014.06.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Accepted: 06/06/2014] [Indexed: 12/17/2022]
Abstract
This article reviews the application of solid-state ²H nuclear magnetic resonance (NMR) spectroscopy for investigating the deformation of lipid bilayers at the atomistic level. For liquid-crystalline membranes, the average structure is manifested by the segmental order parameters (SCD) of the lipids. Solid-state ²H NMR yields observables directly related to the stress field of the lipid bilayer. The extent to which lipid bilayers are deformed by osmotic pressure is integral to how lipid-protein interactions affect membrane functions. Calculations of the average area per lipid and related structural properties are pertinent to bilayer remodeling and molecular dynamics (MD) simulations of membranes. To establish structural quantities, such as area per lipid and volumetric bilayer thickness, a mean-torque analysis of ²H NMR order parameters is applied. Osmotic stress is introduced by adding polymer solutions or by gravimetric dehydration, which are thermodynamically equivalent. Solid-state NMR studies of lipids under osmotic stress probe membrane interactions involving collective bilayer undulations, order-director fluctuations, and lipid molecular protrusions. Removal of water yields a reduction of the mean area per lipid, with a corresponding increase in volumetric bilayer thickness, by up to 20% in the liquid-crystalline state. Hydrophobic mismatch can shift protein states involving mechanosensation, transport, and molecular recognition by G-protein-coupled receptors. Measurements of the order parameters versus osmotic pressure yield the elastic area compressibility modulus and the corresponding bilayer thickness at an atomistic level. Solid-state ²H NMR thus reveals how membrane deformation can affect protein conformational changes within the stress field of the lipid bilayer.
Collapse
Affiliation(s)
- Jacob J Kinnun
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | | | - Horia I Petrache
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Michael F Brown
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, USA; Department of Physics, University of Arizona, Tucson, AZ 85721, USA.
| |
Collapse
|
37
|
Kar P, Gopal SM, Cheng YM, Panahi A, Feig M. Transferring the PRIMO Coarse-Grained Force Field to the Membrane Environment: Simulations of Membrane Proteins and Helix-Helix Association. J Chem Theory Comput 2014; 10:3459-3472. [PMID: 25136271 PMCID: PMC4132866 DOI: 10.1021/ct500443v] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Indexed: 12/03/2022]
Abstract
![]()
An
extension of the recently developed PRIMO coarse-grained force
field to membrane environments, PRIMO-M, is described. The membrane
environment is modeled with the heterogeneous dielectric generalized
Born (HDGB) methodology that simply replaces the standard generalized
Born model in PRIMO without further parametrization. The resulting
model was validated by comparing amino acid insertion free energy
profiles and application in molecular dynamics simulations of membrane
proteins and membrane-interacting peptides. Membrane proteins with
148–661 amino acids show stable root-mean-squared-deviations
(RMSD) between 2 and 4 Å for most systems. Transmembrane helical
peptides maintain helical shape and exhibit tilt angles in good agreement
with experimental or other simulation data. The association of two
glycophorin A (GpA) helices was simulated using replica exchange molecular
dynamics simulations yielding the correct dimer structure with a crossing
angle in agreement with previous studies. Finally, conformational
sampling of the influenza fusion peptide also generates structures
in agreement with previous studies. Overall, these findings suggest
that PRIMO-M can be used to study membrane bound peptides and proteins
and validates the transferable nature of the PRIMO coarse-grained
force field.
Collapse
Affiliation(s)
- Parimal Kar
- Department of Biochemistry and Molecular Biology and Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States
| | - Srinivasa Murthy Gopal
- Department of Biochemistry and Molecular Biology and Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States
| | - Yi-Ming Cheng
- Department of Biochemistry and Molecular Biology and Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States
| | - Afra Panahi
- Departments of Chemistry and Biophysics, University of Michigan , Ann Arbor, Michigan 48109, United States
| | - Michael Feig
- Department of Biochemistry and Molecular Biology and Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States ; Department of Biochemistry and Molecular Biology and Department of Chemistry, Michigan State University , East Lansing, Michigan 48824, United States
| |
Collapse
|
38
|
Carballo-Pacheco M, Vancea I, Strodel B. Extension of the FACTS Implicit Solvation Model to Membranes. J Chem Theory Comput 2014; 10:3163-76. [DOI: 10.1021/ct500084y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Martín Carballo-Pacheco
- Forschungszentrum Jülich GmbH, Institute of Complex
Systems: Structural Biochemistry (ICS-6), 52425 Jülich, Germany
| | - Ioan Vancea
- Forschungszentrum Jülich GmbH, Institute of Complex
Systems: Structural Biochemistry (ICS-6), 52425 Jülich, Germany
| | - Birgit Strodel
- Forschungszentrum Jülich GmbH, Institute of Complex
Systems: Structural Biochemistry (ICS-6), 52425 Jülich, Germany
- Institute
of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Universitätstrasse 1, 40225 Düsseldorf, Germany
| |
Collapse
|
39
|
Javanainen M. Universal Method for Embedding Proteins into Complex Lipid Bilayers for Molecular Dynamics Simulations. J Chem Theory Comput 2014; 10:2577-82. [DOI: 10.1021/ct500046e] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
|
40
|
Song J, Ji C, Zhang JZH. Unveiling the gating mechanism of ECF transporter RibU. Sci Rep 2013; 3:3566. [PMID: 24356467 PMCID: PMC3868957 DOI: 10.1038/srep03566] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 12/04/2013] [Indexed: 11/11/2022] Open
Abstract
Energy-coupling factor (ECF) transporters are responsible for uptake of micronutrients in prokaryotes. The recently reported crystal structure of an ECF transporter RibU provided a foundation for understanding the structure and transport mechanism of ECF transporters. In the present study, molecular dynamics (MD) was carried out to study the conformational changes of the S component RibU upon binding by riboflavin. Our result and analysis revealed a critically important gating mechanism, in which part of loop5 (L5′) (eleven residues, missing in the crystal structure) between TM5 and TM6 is dynamically flexible and serves as a gate. Specifically, the L5′ opens a large cavity accessible to riboflavin from the extracellular space in Apo-RibU and closes the cavity upon riboflavin binding through hydrophobic packing with riboflavin. Thus, L5′is proposed to be the gate for riboflavin binding. In addition, steered molecular dynamics (SMD) simulation is employed to investigate the translocation dynamics of RibU during riboflavin transport. The simulation result does not show evidence that the S component alone can carry out the transport function. Since loop regions are very flexible and therefore could not be resolved by crystallography, their dynamics are hard to predict based on crystal structure alone.
Collapse
Affiliation(s)
- Jianing Song
- State Key Laboratory of Precision Spectroscopy, Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062, China
| | - Changge Ji
- 1] State Key Laboratory of Precision Spectroscopy, Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062, China [2] Institutes for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, China [3] NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai, China 200062
| | - John Z H Zhang
- 1] State Key Laboratory of Precision Spectroscopy, Department of Physics, Institute of Theoretical and Computational Science, East China Normal University, Shanghai 200062, China [2] Institutes for Advanced Interdisciplinary Research, East China Normal University, Shanghai 200062, China [3] NYU-ECNU Center for Computational Chemistry at NYU Shanghai, Shanghai, China 200062
| |
Collapse
|
41
|
Ru Q, Fadda HM, Li C, Paul D, Khaw PT, Brocchini S, Zloh M. Molecular dynamic simulations of ocular tablet dissolution. J Chem Inf Model 2013; 53:3000-8. [PMID: 24073784 DOI: 10.1021/ci4002348] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Small tablets for implantation into the subconjunctival space in the eye are being developed to inhibit scarring after glaucoma filtration surgery (GFS). There is a need to evaluate drug dissolution at the molecular level to determine how the chemical structure of the active may correlate with dissolution in the nonsink conditions of the conjunctival space. We conducted molecular dynamics simulations to study the dissolution process of tablets derived from two drugs that can inhibit fibrosis after GFS, 5-fluorouracil (5-FU) and the matrix metalloprotease inhibitor (MMPi), ilomastat. The dissolution was simulated in the presence of simple point charge (SPC) water molecules, and the liquid turnover of the aqueous humor in the subconjunctival space was simulated by removal of the dissolved drug molecules at regular intervals and replacement by new water molecules. At the end of the simulation, the total molecular solvent accessible surface area of 5-FU tablets increased by 60 times more than that of ilomastat as a result of tablet swelling and release of molecules into solution. The tablet dissolution pattern shown in our molecular dynamic simulations tends to correlate with experimental release profiles. This work indicates that a series of molecular dynamic simulations can be used to predict the influence of the molecular properties of a drug on its dissolution profile and could be useful during preformulation where sufficient amounts of the drug are not always available to perform dissolution studies.
Collapse
Affiliation(s)
- Qian Ru
- UCL School of Pharmacy , 29/39 Brunswick Square, London WC1N 1AX, United Kingdom
| | | | | | | | | | | | | |
Collapse
|
42
|
Zhu S, Brown MF, Feller SE. Retinal conformation governs pKa of protonated Schiff base in rhodopsin activation. J Am Chem Soc 2013; 135:9391-8. [PMID: 23701524 PMCID: PMC5176254 DOI: 10.1021/ja4002986] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have explored the relationship between conformational energetics and the protonation state of the Schiff base in retinal, the covalently bound ligand responsible for activating the G protein-coupled receptor rhodopsin, using quantum chemical calculations. Guided by experimental structural determinations and large-scale molecular simulations on this system, we examined rotation about each bond in the retinal polyene chain, for both the protonated and deprotonated states that represent the dark and photoactivated states, respectively. Particular attention was paid to the torsional degrees of freedom that determine the shape of the molecule, and hence its interactions with the protein binding pocket. While most torsional degrees of freedom in retinal are characterized by large energetic barriers that minimize structural fluctuations under physiological temperatures, the C6-C7 dihedral defining the relative orientation of the β-ionone ring to the polyene chain has both modest barrier heights and a torsional energy surface that changes dramatically with protonation of the Schiff base. This surprising coupling between conformational degrees of freedom and protonation state is further quantified by calculations of the pKa as a function of the C6-C7 dihedral angle. Notably, pKa shifts of greater than two units arise from torsional fluctuations observed in molecular dynamics simulations of the full ligand-protein-membrane system. It follows that fluctuations in the protonation state of the Schiff base occur prior to forming the activated MII state. These new results shed light on important mechanistic aspects of retinal conformational changes that are involved in the activation of rhodopsin in the visual process.
Collapse
Affiliation(s)
- Shengshuang Zhu
- Department of Chemistry, Wabash College, Crawfordsville IN 47933
| | - Michael F. Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson AZ 85721
- Department of Physics, University of Arizona, Tucson AZ 85721
| | - Scott E. Feller
- Department of Chemistry, Wabash College, Crawfordsville IN 47933
| |
Collapse
|
43
|
Yatawara A, Wilson JL, Taylor L, Polgar P, Mierke DF. C-terminus of ETA/ETB receptors regulate endothelin-1 signal transmission. J Pept Sci 2013; 19:257-62. [PMID: 23436727 PMCID: PMC3770155 DOI: 10.1002/psc.2499] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 01/18/2013] [Accepted: 01/23/2013] [Indexed: 11/08/2022]
Abstract
The dimerization of the G protein-coupled receptors for endothelin-1 (ET-1), endothelin A receptor (ETA) and endolethin B receptor (ETB), is well established. However, the signaling consequences of the homodimerization and heterodimerization of ETA and ETB is not well understood. Here, we demonstrate that peptides derived from the C-termini of these receptors regulate the signaling capacity of ET-1. The C-termini of the ETA and ETB receptors are believed to consist of three α-helices, which may serve as points of interaction between the receptors. The third α-helix in the C-terminus is of particular interest because of its amphipathic nature. In a cell line expressing only the ETA receptor, expression of residues Y430-S442, representing the third helix of the ETB C-terminus, leads to a dramatic increase in the signaling induced by ET-1. In contrast, in a cell line containing only ETB , Y430-S442 has an antagonistic effect, slightly reducing the ET-1 induced signal. Computational docking results suggest that the α-helical ETB -derived peptide binds to the second and third intracellular loops of the ETA receptor consistent with the alteration of its signaling capacity. Our results described here provide important insight into ETA /ETB receptor interactions and possibly a new approach to regulate specific G protein-coupled receptor signal transmission.
Collapse
Affiliation(s)
- Achani Yatawara
- Department of Chemistry, Dartmouth College, Hanover, NH, USA
| | - Jamie L. Wilson
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - Linda Taylor
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - Peter Polgar
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - Dale F. Mierke
- Department of Chemistry, Dartmouth College, Hanover, NH, USA
| |
Collapse
|
44
|
Wassenaar TA, Ingólfsson HI, Priess M, Marrink SJ, Schäfer LV. Mixing MARTINI: electrostatic coupling in hybrid atomistic-coarse-grained biomolecular simulations. J Phys Chem B 2013; 117:3516-30. [PMID: 23406326 DOI: 10.1021/jp311533p] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Hybrid molecular dynamics simulations of atomistic (AA) solutes embedded in coarse-grained (CG) environment can substantially reduce the computational cost with respect to fully atomistic simulations. However, interfacing both levels of resolution is a major challenge that includes a balanced description of the relevant interactions. This is especially the case for polar solvents such as water, which screen the electrostatic interactions and thus require explicit electrostatic coupling between AA and CG subsystems. Here, we present and critically test computationally efficient hybrid AA/CG models. We combined the Gromos atomistic force field with the MARTINI coarse-grained force field. To enact electrostatic coupling, two recently developed CG water models with explicit electrostatic interactions were used: the polarizable MARTINI water model and the BMW model. The hybrid model was found to be sensitive to the strength of the AA-CG electrostatic coupling, which was adjusted through the relative dielectric permittivity εr(AA-CG). Potentials of mean force (PMFs) between pairs of amino acid side chain analogues in water and partitioning free enthalpies of uncharged amino acid side chain analogues between apolar solvent and water show significant differences between the hybrid simulations and the fully AA or CG simulations, in particular for charged and polar molecules. For apolar molecules, the results obtained with the hybrid AA/CG models are in better agreement with the fully atomistic results. The structures of atomistic ubiquitin solvated in CG water and of a single atomistic transmembrane α-helix and the transmembrane portion of an atomistic mechanosensitive channel in CG lipid bilayers were largely maintained during 50-100 ns of AA/CG simulations, partly due to an overstabilization of intramolecular interactions. This work highlights some key challenges on the way toward hybrid AA/CG models that are both computationally efficient and sufficiently accurate for biomolecular simulations.
Collapse
Affiliation(s)
- Tsjerk A Wassenaar
- Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | | | | | | | | |
Collapse
|
45
|
Zhang Y, Romsted LS, Zhuang L, de Jong S. Simultaneous determination of interfacial molarities of amide bonds, carboxylate groups, and water by chemical trapping in micelles of amphiphiles containing peptide bond models. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:534-544. [PMID: 23237147 DOI: 10.1021/la3040819] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Chemical trapping is a powerful approach for obtaining experimental estimates of interfacial molarities of weakly basic nucleophiles in the interfacial regions of amphiphile aggregates. Here, we demonstrate that the chemical probe 4-hexadecyl-2,6-dimethylbenzenediazonium ion (16-ArN(2)(+)) reacts competitively with interfacial water, with the amide carbonyl followed by cleavage of the headgroups from the tail at the amide oxygen, and with the terminal carboxylate groups in micelles of two N-acyl amino-acid amphiphiles, sodium N-lauroylsarcosinate (SLS) and sodium N-lauroylglycinate (SLG), simple peptide bond model amphiphiles. Interfacial molarities (in moles per liter of interfacial volume) of these three groups were obtained from product yields, assuming that selectivity toward a particular nucleophile compared to water is the same in an aqueous reference solution and in the interfacial region. Interfacial carboxylate group molarities are ~1.5 M in both SLS and SLG micelles, but the concentration of the amide carbonyl for SLS micelles is ~4.6-5 times less (ca. 0.7 M) than that of SLG micelles (~3 M). The proton on the secondary N of SLG helps solubilize the amide bond in the aqueous region, but the methyl on the tertiary N of SLS helps solubilize the amide bond in the micellar core, reducing its reaction with 16-ArN(2)(+). Application of chemical trapping to proteins in membrane mimetic interfaces should provide insight into the topology of the protein within the interface because trapping of the amide carbonyl and cleavage at the C-N bond occurs only within the interface, and fragment characterization marks those peptide bonds located within the interface.
Collapse
Affiliation(s)
- Yongliang Zhang
- Department of Chemistry and Chemical Biology, Wright-Rieman Laboratories, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08903, United States
| | | | | | | |
Collapse
|
46
|
Paramo T, Garzón D, Holdbrook DA, Khalid S, Bond PJ. The simulation approach to lipid-protein interactions. Methods Mol Biol 2013; 974:435-455. [PMID: 23404287 DOI: 10.1007/978-1-62703-275-9_19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The interactions between lipids and proteins are crucial for a range of biological processes, from the folding and stability of membrane proteins to signaling and metabolism facilitated by lipid-binding proteins. However, high-resolution structural details concerning functional lipid/protein interactions are scarce due to barriers in both experimental isolation of native lipid-bound complexes and subsequent biophysical characterization. The molecular dynamics (MD) simulation approach provides a means to complement available structural data, yielding dynamic, structural, and thermodynamic data for a protein embedded within a physiologically realistic, modelled lipid environment. In this chapter, we provide a guide to current methods for setting up and running simulations of membrane proteins and soluble, lipid-binding proteins, using standard atomistically detailed representations, as well as simplified, coarse-grained models. In addition, we outline recent studies that illustrate the power of the simulation approach in the context of biologically relevant lipid/protein interactions.
Collapse
Affiliation(s)
- Teresa Paramo
- Department of Chemistry, Unilever Centre for Molecular Informatics, University of Cambridge, Cambridge, UK
| | | | | | | | | |
Collapse
|
47
|
Abstract
The time and length scales accessible by biomolecular simulations continue to increase. This is in part due to improvements in algorithms and computing performance, but is also the result of the emergence of coarse-grained (CG) potentials, which complement and extend the information obtainable from fully detailed models. CG methods have already proven successful for a range of applications that benefit from the ability to rapidly simulate spontaneous self-assembly within a lipid membrane environment, including the insertion and/or oligomerization of a range of "toy models," transmembrane peptides, and single- and multi-domain proteins. While these simplified approaches sacrifice atomistic level detail, it is now straightforward to "reverse map" from CG to atomistic descriptions, providing a strategy to assemble membrane proteins within a lipid environment, prior to all-atom simulation. Moreover, recent developments have been made in "dual resolution" techniques, allowing different molecules in the system to be modeled with atomistic or CG resolution simultaneously.
Collapse
Affiliation(s)
- Syma Khalid
- School of Chemistry, University of Southampton, Southampton, UK
| | | |
Collapse
|
48
|
Maffeo C, Bhattacharya S, Yoo J, Wells D, Aksimentiev A. Modeling and simulation of ion channels. Chem Rev 2012; 112:6250-84. [PMID: 23035940 PMCID: PMC3633640 DOI: 10.1021/cr3002609] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Christopher Maffeo
- Department of Physics, University of Illinois, 1110 W. Green St., Urbana, IL
| | - Swati Bhattacharya
- Department of Physics, University of Illinois, 1110 W. Green St., Urbana, IL
| | - Jejoong Yoo
- Department of Physics, University of Illinois, 1110 W. Green St., Urbana, IL
| | - David Wells
- Department of Physics, University of Illinois, 1110 W. Green St., Urbana, IL
| | - Aleksei Aksimentiev
- Department of Physics, University of Illinois, 1110 W. Green St., Urbana, IL
| |
Collapse
|
49
|
Abstract
Membrane biochemists are becoming increasingly aware of the role of lipid-protein interactions in diverse cellular functions. This review describes how conformational changes in membrane proteins, involving folding, stability, and membrane shape transitions, potentially involve elastic remodeling of the lipid bilayer. Evidence suggests that membrane lipids affect proteins through interactions of a relatively long-range nature, extending beyond a single annulus of next-neighbor boundary lipids. It is assumed the distance scale of the forces is large compared to the molecular range of action. Application of the theory of elasticity to flexible soft surfaces derives from classical physics and explains the polymorphism of both detergents and membrane phospholipids. A flexible surface model (FSM) describes the balance of curvature and hydrophobic forces in lipid-protein interactions. Chemically nonspecific properties of the lipid bilayer modulate the conformational energetics of membrane proteins. The new biomembrane model challenges the standard model (the fluid mosaic model) found in biochemistry texts. The idea of a curvature force field based on data first introduced for rhodopsin gives a bridge between theory and experiment. Influences of bilayer thickness, nonlamellar-forming lipids, detergents, and osmotic stress are all explained by the FSM. An increased awareness of curvature forces suggests that research will accelerate as structural biology becomes more closely entwined with the physical chemistry of lipids in explaining membrane structure and function.
Collapse
Affiliation(s)
- Michael F Brown
- Department of Chemistry and Biochemistry and Department of Physics, University of Arizona, Tucson, AZ 85721, USA.
| |
Collapse
|
50
|
Jämbeck JPM, Lyubartsev AP. Another Piece of the Membrane Puzzle: Extending Slipids Further. J Chem Theory Comput 2012; 9:774-84. [PMID: 26589070 DOI: 10.1021/ct300777p] [Citation(s) in RCA: 210] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
To be able to model complex biological membranes in a more realistic manner, the force field Slipids (Stockholm lipids) has been extended to include parameters for sphingomyelin (SM), phosphatidylglycerol (PG), phosphatidylserine (PS) lipids, and cholesterol. Since the parametrization scheme was faithful to the scheme used in previous editions of Slipids, all parameters are consistent and fully compatible. The results of careful validation of a number of key structural properties for one and two component lipid bilayers are in excellent agreement with experiments. Potentials of mean force for transferring water across binary mixtures of lipids and cholesterol were also computed in order to compare water permeability rates to experiments. In agreement with experimental and simulation studies, it was found that the permeability and partitioning of water is affected by cholesterol in lipid bilayers made of saturated lipids to the largest extent. With the extensions of Slipids presented here, it is now possible to study complex systems containing many different lipids and proteins in a fully atomistic resolution in the isothermic-isobaric (NPT) ensemble, which is the proper ensemble for membrane simulations.
Collapse
Affiliation(s)
- Joakim P M Jämbeck
- Division of Physical Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, SE-10691, Sweden
| | - Alexander P Lyubartsev
- Division of Physical Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, SE-10691, Sweden
| |
Collapse
|