1
|
Vaiwala R, Ayappa KG. Martini-3 Coarse-Grained Models for the Bacterial Lipopolysaccharide Outer Membrane of Escherichia coli. J Chem Theory Comput 2024; 20:1704-1716. [PMID: 37676287 DOI: 10.1021/acs.jctc.3c00471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
The outer lipopolysaccharide (LPS) membrane of Gram-negative bacteria forms the main barrier for transport of antimicrobial molecules into the bacterial cell. In this study we develop coarse-grained models for the outer membrane of Escherichia coli in the Martini-3 framework. The coarse-grained model force field was parametrized and validated using all-atom simulations of symmetric membranes of lipid A and rough LPS as well as a complete asymmetric membrane of LPS with the O-antigen. The bonded parameters were obtained using an iterative refinement procedure with target bonded distributions obtained from all-atom simulations. The membrane thickness, area of the LPS, and density distributions for the different regions as well as the water and ion densities in Martini-3 simulations show excellent agreement with the all-atom data. Additionally the solvent accessible surface area for individual molecules in water was found to be in good agreement. The binding of calcium ions with phosphate and carboxylate moieties of LPS is accurately captured in the Martini-3 model, indicative of the integrity of the highly negatively charged LPS molecules in the outer membranes of Gram-negative bacteria. The melting transition of the coarse-grained lipid A membrane model was found to occur between 300 and 310 K, and the model captured variations in area per LPS, order parameter, and membrane thickness across the melting transition. Our study reveals that the proposed Martini-3 models for LPS are able to capture the physicochemical balance of the complex sugar architecture of the outer membrane of Escherichia coli. The coarse-grained models developed in this study would be useful for determining membrane protein interactions and permeation of potential antimicrobials through bacterial membranes at mesoscopic spatial and temporal scales.
Collapse
Affiliation(s)
- Rakesh Vaiwala
- Department of Chemical Engineering, Indian Institute of Science, Bangalore 560012, India
| | - K Ganapathy Ayappa
- Department of Chemical Engineering, Indian Institute of Science, Bangalore 560012, India
| |
Collapse
|
2
|
Mai TL, Derreumaux P, Nguyen PH. Structure and Elasticity of Mitochondrial Membranes: A Molecular Dynamics Simulation Study. J Phys Chem B 2023; 127:10778-10791. [PMID: 38084584 DOI: 10.1021/acs.jpcb.3c05112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
Mitochondria are known as the powerhouse of the cell because they produce energy in the form of adenosine triphosphate. They also have other crucial functions such as regulating apoptosis, calcium homeostasis, and reactive oxygen species production. To perform these diverse functions, mitochondria adopt specific structures and frequently undergo dynamic shape changes, indicating that their mechanical properties play an essential role in their functions. To gain a detailed understanding at the molecular level of the structure and mechanical properties of mitochondria, we carry out atomistic molecular dynamics simulations for three inner mitochondrial membranes and three outer mitochondrial membrane models. These models take into account variations in cardiolipin and cholesterol concentrations as well as the symmetry/asymmetry between the two leaflets. Our simulations allow us to calculate various structural quantities and the bending, twisting, and tilting elastic moduli of the membrane models. Our results indicate that the structures of the inner and outer mitochondrial membranes are quite similar and do not depend much on the variation in lipid compositions. However, the bending modulus of the membranes increases with increasing concentrations of cardiolipin or cholesterol but decreases with a membrane asymmetry. Notably, we found that the dipole potential of the membrane increases with an increasing cardiolipin concentration. Finally, possible roles of cardiolipin in regulating ion and proton currents and maintaining the cristate are discussed in some details.
Collapse
Affiliation(s)
- Thi Ly Mai
- CNRS, Université Paris Cité, UPR9080, Laboratoire de Biochimie Théorique, Institute de Biologie Physico-Chimique, Fondation Edmond de Rothschild, 13 rue Pierre et Marie Curie, Paris 75005, France
| | - Philippe Derreumaux
- CNRS, Université Paris Cité, UPR9080, Laboratoire de Biochimie Théorique, Institute de Biologie Physico-Chimique, Fondation Edmond de Rothschild, 13 rue Pierre et Marie Curie, Paris 75005, France
- Institut Universitaire de France (IUF), Paris 75005, France
| | - Phuong H Nguyen
- CNRS, Université Paris Cité, UPR9080, Laboratoire de Biochimie Théorique, Institute de Biologie Physico-Chimique, Fondation Edmond de Rothschild, 13 rue Pierre et Marie Curie, Paris 75005, France
| |
Collapse
|
3
|
Grillo DA, Albano JMR, Valladares T. RE, Mocskos EE, Facelli JC, Pickholz M, Ferraro MB. Molecular dynamics study of the mechanical properties of drug loaded model systems: A comparison of a polymersome with a bilayer. J Chem Phys 2023; 159:174908. [PMID: 37929867 PMCID: PMC10629967 DOI: 10.1063/5.0165478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 10/16/2023] [Indexed: 11/07/2023] Open
Abstract
In this work we implement a new methodology to study structural and mechanical properties of systems having spherical and planar symmetries throughout Molecular Dynamics simulations. This methodology is applied here to a drug delivery system based in polymersomes, as an example. The chosen model drug was the local anesthetic prilocaine due to previous parameterization within the used coarse grain scheme. In our approach, mass density profiles (MDPs) are used to obtain key structural parameters of the systems, and pressure profiles are used to estimate the curvature elastic parameters. The calculation of pressure profiles and radial MPDs required the development of specific methods, which were implemented in an in-house built version of the GROMACS 2018 code. The methodology presented in this work is applied to characterize poly(ethylene oxide)-poly(butadiene) polymersomes and bilayers loaded with the model drug prilocaine. Our results show that structural properties of the polymersome membrane could be obtained from bilayer simulations, with significantly lower computational cost compared to whole polymersome simulations, but the bilayer simulations are insufficient to get insights on their mechanical aspects, since the elastic parameters are canceled out for the complete bilayer (as consequence of the symmetry). The simulations of entire polymersomes, although more complex, offer a complementary approach to get insights on the mechanical behavior of the systems.
Collapse
Affiliation(s)
| | - Juan M. R. Albano
- CONICET - Universidad de Buenos Aires, Instituto de Física de Buenos Aires (IFIBA), Buenos Aires, Argentina
| | - Rufino E. Valladares T.
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Física, Buenos Aires, Argentina
| | | | - Julio C. Facelli
- Department of Biomedical Informatics, University of Utah, 421 Wakara Way, Suite 140, Salt Lake City, Utah 84108, USA
| | | | | |
Collapse
|
4
|
Na H, Song G. Coarse-Graining Waters: Unveiling The Effective Hydrophilicity/Hydrophobicity of Individual Protein Atoms and The Roles of Waters' Hydrogens. J Chem Theory Comput 2023; 19:7307-7323. [PMID: 37782694 PMCID: PMC10601925 DOI: 10.1021/acs.jctc.3c00700] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Indexed: 10/04/2023]
Abstract
There have been many coarse-graining methods developed that aim to reduce the sizes of simulated systems and their computational costs. In this work, we develop a new coarse-graining method, called coarse-graining-delta (or δ-CG in short), that reduces the degrees of freedom of the potential energy surface by coarse-graining relative locations of atoms from their unit centers. Our method extends and generalizes the methods used in the coarse-grained normal mode analysis and enables us to study the roles of the individual removed atoms in a system, which have been difficult to study in molecular dynamics simulations. By applying δ-CG to coarse-grain three-point water molecules into single-point solvent particles, we successfully identify the effective hydrophilicity and hydrophobicity of all the individual protein atom types, which collectively correlate well with the known hydrophilic, hydrophobic, and amphipathic characteristics of amino acids. Moreover, our investigation shows that water's hydrogens have two roles in interacting with protein atoms. First, water molecules adjust their poses around different amino acids and their atoms, and the statistical preferences of the hydrogen poses near the atoms determine the effective hydrophilicity and hydrophobicity of the atoms, which have not been successfully addressed before. Second, the collective dynamics of the hydrogens assist the water molecules in escaping from the potential energy wells of the hydrophilic atoms. Our method also shows that coarse-graining a system mathematically leads to breaking antisymmetry of the nonbonded interactions; as a result, two interacting coarse-grained units exert different forces on each other. Our study indicates that the accuracy of coarse-grained force fields, such as the MARTINI force field and the UNRES force field, can be improved in two ways: (i) refining their potential energy functions and coefficients by analyzing the coarse-grained potential energy surface using δ-CG, and (ii) introducing non-antisymmetric interactions.
Collapse
Affiliation(s)
- Hyuntae Na
- Department
of Computer Science, Penn State Harrisburg, Middletown, Pennsylvania 17057, United States
| | - Guang Song
- Department
of Mathematics and Computer Science, Westmont
College, Santa
Barbara, California 93108, United States
| |
Collapse
|
5
|
Ouyang J, Sheng Y, Wang W. Recent Advances of Studies on Cell-Penetrating Peptides Based on Molecular Dynamics Simulations. Cells 2022; 11:cells11244016. [PMID: 36552778 PMCID: PMC9776715 DOI: 10.3390/cells11244016] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/09/2022] [Accepted: 12/10/2022] [Indexed: 12/14/2022] Open
Abstract
With the ability to transport cargo molecules across cell membranes with low toxicity, cell-penetrating peptides (CPPs) have become promising candidates for next generation peptide-based drug delivery vectors. Over the past three decades since the first CPP was discovered, a great deal of work has been done on the cellular uptake mechanisms and the applications for the delivery of therapeutic molecules, and significant advances have been made. But so far, we still do not have a precise and unified understanding of the structure-activity relationship of the CPPs. Molecular dynamics (MD) simulations provide a method to reveal peptide-membrane interactions at the atomistic level and have become an effective complement to experiments. In this paper, we review the progress of the MD simulations on CPP-membrane interactions, including the computational methods and technical improvements in the MD simulations, the research achievements in the CPP internalization mechanism, CPP decoration and coupling, and the peptide-induced membrane reactions during the penetration process, as well as the comparison of simulated and experimental results.
Collapse
Affiliation(s)
- Jun Ouyang
- School of Public Courses, Bengbu Medical College, Bengbu 233030, China
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing 210093, China
| | - Yuebiao Sheng
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing 210093, China
- High Performance Computing Center, Nanjing University, Nanjing 210093, China
- Correspondence: (Y.S.); (W.W.)
| | - Wei Wang
- Collaborative Innovation Center of Advanced Microstructures, National Laboratory of Solid State Microstructure, Department of Physics, Nanjing University, Nanjing 210093, China
- Correspondence: (Y.S.); (W.W.)
| |
Collapse
|
6
|
Membrane Lipid Reshaping Underlies Oxidative Stress Sensing by the Mitochondrial Proteins UCP1 and ANT1. Antioxidants (Basel) 2022; 11:antiox11122314. [PMID: 36552523 PMCID: PMC9774536 DOI: 10.3390/antiox11122314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 11/17/2022] [Accepted: 11/18/2022] [Indexed: 11/24/2022] Open
Abstract
Oxidative stress and ROS are important players in the pathogenesis of numerous diseases. In addition to directly altering proteins, ROS also affects lipids with negative intrinsic curvature such as phosphatidylethanolamine (PE), producing PE adducts and lysolipids. The formation of PE adducts potentiates the protonophoric activity of mitochondrial uncoupling proteins, but the molecular mechanism remains unclear. Here, we linked the ROS-mediated change in lipid shape to the mechanical properties of the membrane and the function of uncoupling protein 1 (UCP1) and adenine nucleotide translocase 1 (ANT1). We show that the increase in the protonophoric activity of both proteins occurs due to the decrease in bending modulus in lipid bilayers in the presence of lysophosphatidylcholines (OPC and MPC) and PE adducts. Moreover, MD simulations showed that modified PEs and lysolipids change the lateral pressure profile of the membrane in the same direction and by the similar amplitude, indicating that modified PEs act as lipids with positive intrinsic curvature. Both results indicate that oxidative stress decreases stored curvature elastic stress (SCES) in the lipid bilayer membrane. We demonstrated that UCP1 and ANT1 sense SCES and proposed a novel regulatory mechanism for the function of these proteins. The new findings should draw the attention of the scientific community to this important and unexplored area of redox biochemistry.
Collapse
|
7
|
Medjmedj A, Ngalle-Loth A, Clemençon R, Hamacek J, Pichon C, Perche F. In Cellulo and In Vivo Comparison of Cholesterol, Beta-Sitosterol and Dioleylphosphatidylethanolamine for Lipid Nanoparticle Formulation of mRNA. NANOMATERIALS 2022; 12:nano12142446. [PMID: 35889670 PMCID: PMC9317807 DOI: 10.3390/nano12142446] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 07/13/2022] [Accepted: 07/14/2022] [Indexed: 12/10/2022]
Abstract
Lipid Nanoparticles (LNPs) are a leading class of mRNA delivery systems. LNPs are made of an ionizable lipid, a polyethyleneglycol (PEG)-lipid conjugate and helper lipids. The success of LNPs is due to proprietary ionizable lipids and appropriate helper lipids. Using a benchmark lipid (D-Lin-MC3) we compared the ability of three helper lipids to transfect dendritic cells in cellulo and in vivo. Studies revealed that the choice of helper lipid does not influence the transfection efficiency of immortalized cells but, LNPs prepared with DOPE (dioleylphosphatidylethanolamine) and β-sitosterol were more efficient for mRNA transfection in murine dendritic cells than LNPs containing DSPC (distearoylphosphatidylcholine). This higher potency of DOPE and β-sitosterol LNPs for mRNA expression was also evident in vivo but only at low mRNA doses. Overall, these data provide valuable insight for the design of novel mRNA LNP vaccines.
Collapse
Affiliation(s)
- Ayoub Medjmedj
- Centre de Biophysique Moléculaire, UPR4301 CNRS, Rue Charles Sadron, 45071 Orléans, France; (A.M.); (A.N.-L.); (R.C.); (J.H.); (C.P.)
| | - Albert Ngalle-Loth
- Centre de Biophysique Moléculaire, UPR4301 CNRS, Rue Charles Sadron, 45071 Orléans, France; (A.M.); (A.N.-L.); (R.C.); (J.H.); (C.P.)
| | - Rudy Clemençon
- Centre de Biophysique Moléculaire, UPR4301 CNRS, Rue Charles Sadron, 45071 Orléans, France; (A.M.); (A.N.-L.); (R.C.); (J.H.); (C.P.)
| | - Josef Hamacek
- Centre de Biophysique Moléculaire, UPR4301 CNRS, Rue Charles Sadron, 45071 Orléans, France; (A.M.); (A.N.-L.); (R.C.); (J.H.); (C.P.)
- Centre de Biophysique Moléculaire, University of Orléans, 45100 Orléans, France
| | - Chantal Pichon
- Centre de Biophysique Moléculaire, UPR4301 CNRS, Rue Charles Sadron, 45071 Orléans, France; (A.M.); (A.N.-L.); (R.C.); (J.H.); (C.P.)
- Centre de Biophysique Moléculaire, University of Orléans, 45100 Orléans, France
| | - Federico Perche
- Centre de Biophysique Moléculaire, UPR4301 CNRS, Rue Charles Sadron, 45071 Orléans, France; (A.M.); (A.N.-L.); (R.C.); (J.H.); (C.P.)
- Correspondence: ; Tel.: +33-2-38-25-55-44
| |
Collapse
|
8
|
Parchekani J, Allahverdi A, Taghdir M, Naderi-Manesh H. Design and simulation of the liposomal model by using a coarse-grained molecular dynamics approach towards drug delivery goals. Sci Rep 2022; 12:2371. [PMID: 35149771 PMCID: PMC8837752 DOI: 10.1038/s41598-022-06380-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 01/27/2022] [Indexed: 12/19/2022] Open
Abstract
The simulated liposome models provide events in molecular biological science and cellular biology. These models may help to understand the cell membrane mechanisms, biological cell interactions, and drug delivery systems. In addition, the liposomes model may resolve specific issues such as membrane transports, ion channels, drug penetration in the membrane, vesicle formation, membrane fusion, and membrane protein function mechanism. One of the approaches to investigate the lipid membranes and the mechanism of their formation is by molecular dynamics (MD) simulations. In this study, we used the coarse-grained MD simulation approach and designed a liposome model system. To simulate the liposome model, we used phospholipids that are present in the structure of natural cell membranes (1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-Dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE)). Simulation conditions such as temperature, ions, water, lipid concentration were performed based on experimental conditions. Our results showed a liposome model (ellipse vesicle structure) during the 2100 ns was formed. Moreover, the analysis confirmed that the stretched and ellipse structure is the best structure that could be formed. The eukaryotic and even the bacterial cells have elliptical and flexible structures. Usually, an elliptical structure is more stable than other assembled structures. The results indicated the assembly of the lipids is directed through short-range interactions (electrostatic interactions and, van der Waals interactions). Total energy (Van der Waals and electrostatic interaction energy) confirmed the designed elliptical liposome structure has suitable stability at the end of the simulation process. Our findings confirmed that phospholipids DOPC and DOPE have a good tendency to form bilayer membranes (liposomal structure) based on their geometric shapes and chemical-physical properties. Finally, we expected the simulated liposomal structure as a simple model to be useful in understanding the function and structure of biological cell membranes. Furthermore, it is useful to design optimal, suitable, and biocompatible liposomes as potential drug carriers.
Collapse
Affiliation(s)
- Jalil Parchekani
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, 14115-154, Iran
| | - Abdollah Allahverdi
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, 14115-154, Iran
| | - Majid Taghdir
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, 14115-154, Iran.
| | - Hossein Naderi-Manesh
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, 14115-154, Iran.
- Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, 14115-154, Iran.
| |
Collapse
|
9
|
Chng CP, Wang K, Ma W, Hsia KJ, Huang C. Chloroplast membrane lipid remodeling protects against dehydration by limiting membrane fusion and distortion. PLANT PHYSIOLOGY 2022; 188:526-539. [PMID: 34730798 PMCID: PMC8774810 DOI: 10.1093/plphys/kiab512] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Accepted: 10/06/2021] [Indexed: 06/13/2023]
Abstract
Dehydration damages the structural integrity of the chloroplast membrane and, consequently, the normal photosynthetic function of this organelle. Remodeling of galactolipids by converting monogalactosyl-diacylglycerol (MGDG) to digalactosyl-diacylglycerol (DGDG) and oligo-galactolipids is an effective adaptation strategy for protecting against dehydration damage to the chloroplast membrane. However, detailed molecular mechanisms are missing. In this study, by performing molecular-level simulations of bi-lamellar membranes under various dehydration conditions, we find that MGDG-to-DGDG remodeling protects the chloroplast membrane in a unique manner by simultaneously dictating both the extent and the pattern of fusion stalks formed with the apposed membrane. Specifically, MGDG-rich membranes form elongated stalks at a moderate dehydration level, whereas DGDG-rich membranes form smaller, rounded stalks. Simulations of wild-type and mutant Arabidopsis (Arabidopsis thaliana) outer chloroplast membranes further confirm that the mutant membrane without galactolipid remodeling is more susceptible to membrane fusion due to its higher MGDG content. Our work reveals the underlying physical mechanisms that govern the pattern and extent of membrane fusion structures, paving the way for rational genetic engineering of crops with improved dehydration tolerance.
Collapse
Affiliation(s)
- Choon-Peng Chng
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Republic of Singapore
| | - Kun Wang
- Department of Molecular Metabolism, Harvard T. H. Chan School of Public Health, Boston MA 02115, USA
- Department of Cell Biology, Harvard Medical School, Boston MA 02115, USA
| | - Wei Ma
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Republic of Singapore
| | - K Jimmy Hsia
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Republic of Singapore
- School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Republic of Singapore
| | - Changjin Huang
- School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798, Republic of Singapore
| |
Collapse
|
10
|
Mahmoudzadeh M, Magarkar A, Koivuniemi A, Róg T, Bunker A. Mechanistic Insight into How PEGylation Reduces the Efficacy of pH-Sensitive Liposomes from Molecular Dynamics Simulations. Mol Pharm 2021; 18:2612-2621. [PMID: 34096310 PMCID: PMC8289284 DOI: 10.1021/acs.molpharmaceut.1c00122] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Liposome-based drug
delivery systems composed of DOPE stabilized
with cholesteryl hemisuccinate (CHMS) have been proposed as a drug
delivery mechanism with pH-triggered release as the anionic form (CHSa)
is protonated (CHS) at reduced pH; PEGylation is known to decrease
this pH sensitivity. In this manuscript, we set out to use molecular
dynamics (MD) simulations with a model with all-atom resolution to
provide insight into why incorporation of poly(ethyleneglycol) (PEG)
into DOPE–CHMS liposomes reduces their pH sensitivity; we also
address two additional questions: (1) How CHSa stabilizes DOPE bilayers
into a lamellar conformation at a physiological pH of 7.4? and (2)
how the change from CHSa to CHS at acidic pH triggers the destabilization
of DOPE bilayers? We found that (A) CHSa stabilizes the DOPE lipid
membrane by increasing the hydrophilicity of the bilayer surface,
(B) when CHSa changes to CHS by pH reduction, DOPE bilayers are destabilized
due to a reduction in bilayer hydrophilicity and a reduction in the
area per lipid, and (C) PEG stabilizes DOPE bilayers into the lamellar
phase, thus reducing the pH sensitivity of the liposomes by increasing
the area per lipid through penetration into the bilayer, which is
our main focus.
Collapse
Affiliation(s)
- Mohammad Mahmoudzadeh
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, 00100 Helsinki, Finland
| | - Aniket Magarkar
- Medicinal Chemistry, Boehringer Ingelheim Pharma GmbH & Co. KG, Birkendorfer Strasse 65, D-88397 Biberach a.d. Riss, Germany
| | - Artturi Koivuniemi
- Drug Research Program, Division of Pharmaceutical Biosciences, Faculty of Pharmacy, University of Helsinki, 00100 Helsinki, Finland
| | - Tomasz Róg
- Faculty of Pharmacy, University of Helsinki, P.O. Box 56, Viikinkaarie 5 E, FI-00014 Helsinki, Finland
| | - Alex Bunker
- Faculty of Pharmacy, University of Helsinki, P.O. Box 56, Viikinkaarie 5 E, FI-00014 Helsinki, Finland
| |
Collapse
|
11
|
Bozelli JC, Aulakh SS, Epand RM. Membrane shape as determinant of protein properties. Biophys Chem 2021; 273:106587. [PMID: 33865153 DOI: 10.1016/j.bpc.2021.106587] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/26/2021] [Accepted: 03/26/2021] [Indexed: 11/30/2022]
Abstract
Membrane lipids play a role in the modulation of a variety of biological processes. This is often achieved through fine-tuned changes in membrane physical and chemical properties. While some membrane physical properties (e.g., curvature, lipid domains, fluidity) have received increased scientific attention over the years, only recently has membrane shape emerged as an active modulator of protein properties. Biological membranes are mostly found organized into a lipid bilayer arrangement, in which the spontaneous shape is an intrinsically flat, planar morphology (in relation to the size of proteins). However, it is known that many cells and organelles have non-planar morphologies. In addition, perturbations in membrane morphology occur in a variety of biological processes. Recent studies have shown that membrane shape can modulate a variety of biological processes by determining protein properties. While membrane shape generation modulates proteins via changes in membrane mechanical properties, membrane shape recognition regulates proteins by providing the optimal surface for interaction. Hence, membranes have evolved an elegant mechanism to couple mesoscopic perturbations to molecular properties and vice-versa. In this review, the regulation of the enzymatic properties of two isoforms of mammalian diacylglycerol kinase, which play important roles in cellular signal transductions, will be used to exemplify the recent advancements in the field of membrane shape recognition, as well as future challenges and perspectives.
Collapse
Affiliation(s)
- José Carlos Bozelli
- Department of Biochemistry and Biomedical Sciences, McMaster University, Health Sciences Centre, Hamilton, Ontario, Canada.
| | - Sukhvershjit S Aulakh
- Department of Biochemistry and Biomedical Sciences, McMaster University, Health Sciences Centre, Hamilton, Ontario, Canada
| | - Richard M Epand
- Department of Biochemistry and Biomedical Sciences, McMaster University, Health Sciences Centre, Hamilton, Ontario, Canada.
| |
Collapse
|
12
|
Noh SY, Notman R. Comparison of umbrella sampling and steered molecular dynamics methods for computing free energy profiles of aromatic substrates through phospholipid bilayers. J Chem Phys 2021; 153:034115. [PMID: 32716163 DOI: 10.1063/5.0016114] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Understanding the permeation of molecules through lipid membranes is fundamental for predicting the cellular uptake of solutes and drug delivery mechanisms. In molecular simulations, the usual approach is to compute the free energy (FE) profile of a molecule across a model lipid bilayer, which can then be used to estimate the permeability of the molecule. Umbrella Sampling (US), which involves carrying out a series of biased simulations along a defined reaction coordinate (usually the bilayer normal direction), is a popular method for the computation of such FE profiles. However, US can be challenging to implement because the results are dependent on the strength of the biasing potential and the spacing of windows along the reaction coordinate, which, in practice, are usually optimized by an inefficient trial and error approach. The Steered Molecular Dynamics implementation of the Jarzynski Equality (JE-SMD) has been identified as an alternative to equilibrium sampling methods for measuring the FE change across a reaction coordinate. In the JE-SMD approach, equilibrium FE values are evaluated from the average of rapid non-equilibrium trajectories, thus avoiding the practical issues that come with US. Here, we use three different corrections of the JE-SMD method to calculate the FE change for the translocation of two aromatic substrates, phenylalanine and toluene, across a lipid bilayer and compare the accuracy and computational efficiency of these approaches to the results obtained using US. We show evidence that when computing the free energy profile, the JE-SMD approach suffers from insufficient sampling convergence of the bilayer environment and is dependent on the characteristic of the aromatic substrate itself. We deduce that, despite its drawbacks, US remains the more viable approach of the two for computing the FE profile.
Collapse
Affiliation(s)
- Sang Young Noh
- Department of Chemistry, University of Warwick, Coventry, United Kingdom
| | - Rebecca Notman
- Department of Chemistry, University of Warwick, Coventry, United Kingdom
| |
Collapse
|
13
|
Löffler PMG, Rabe A, Vogel S. Lipid-Modified Peptide Nucleic Acids: Synthesis and Application to Programmable Liposome Fusion. Methods Mol Biol 2021; 2105:75-96. [PMID: 32088865 DOI: 10.1007/978-1-0716-0243-0_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Peptide nucleic acids (PNAs) can be modified with aliphatic lipid chains and designed to be water soluble and able to spontaneously insert into phospholipid bilayers. Liposomes with 1.5% negatively charged POPG can be driven to fuse and mix their inner content volumes via functionalization with such lipidated peptide nucleic acids (LiPNAs). During fusion, only low amounts of leakage occur (<5%). We describe here the synthesis and purification of such LiPNAs using an automated peptide synthesizer and the preparation of LiPNA functionalized liposomes. Further, we describe the measurement of LiPNA-induced fusion using a fluorescence-based assay for the content mixing between a liposome population with an encapsulated self-quenching fluorescent dye (SRB) and a buffer-filled liposome population.
Collapse
Affiliation(s)
- Philipp M G Löffler
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Alexander Rabe
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark
| | - Stefan Vogel
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense, Denmark.
| |
Collapse
|
14
|
Jing H, Wang Y, Desai PR, Ramamurthi KS, Das S. Formation and Properties of a Self-Assembled Nanoparticle-Supported Lipid Bilayer Probed through Molecular Dynamics Simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:5524-5533. [PMID: 32362127 PMCID: PMC7494177 DOI: 10.1021/acs.langmuir.0c00593] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We have carried out coarse-grained molecular dynamics (MD) simulations to study the self-assembly procedure of a system of randomly placed lipid molecules, water beads, and a nanoparticle (NP). The self-assembly results in the formation of the nanoparticle-supported lipid bilayer (NPSLBL), with the self-assembly mechanism being driven by events such as the formation of small lipid clusters, merging of the lipid clusters in the vicinity of the NP to form NP-embedded vesicle with a pore, and collapsing of that pore to eventually form the equilibrated NPSLBL system overcoming a large free-energy barrier. Subsequently, we quantify the properties and the configurations of this NPSLBL system. We reveal that unlike our proposition of an equal number of lipid molecules occupying the inner and outer leaflets in a recent report studying the properties of a preassembled lipid bilayer, the equilibrated self-assembled NPSLBL system demonstrates a much larger number of lipid molecules occupying the outer leaflet as compared to the inner leaflet. Second, the thickness of the water layer entrapped between the NP and the inner leaflet shows similar values as predicted by experiments and our previous study. Finally, we reveal that, similar to our previous study, the diffusivity of the lipid molecules in the outer leaflet is larger than that in the inner leaflet but, due to higher temperature employed during our simulations, are even larger than that predicted by our previous study.
Collapse
Affiliation(s)
- Haoyuan Jing
- Department of Mechanical Engineering, University of Maryland, 4298 Campus Drive, College Park, MD 20742
| | - Yanbin Wang
- Department of Mechanical Engineering, University of Maryland, 4298 Campus Drive, College Park, MD 20742
| | - Parth Rakesh Desai
- Department of Mechanical Engineering, University of Maryland, 4298 Campus Drive, College Park, MD 20742
| | - Kumaran S. Ramamurthi
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Siddhartha Das
- Department of Mechanical Engineering, University of Maryland, 4298 Campus Drive, College Park, MD 20742
| |
Collapse
|
15
|
de Souza RM, Ratochinski RH, Karttunen M, Dias LG. Self-Assembly of Phosphocholine Derivatives Using the ELBA Coarse-Grained Model: Micelles, Bicelles, and Reverse Micelles. J Chem Inf Model 2020; 60:522-536. [PMID: 31714768 DOI: 10.1021/acs.jcim.9b00790] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The ELBA coarse-grained force field was originally developed for lipids, and its water model is described as a single-site Lennard-Jones particle with electrostatics modeled by an embedded point-dipole, while other molecules in this force field have a three (or four)-to-one mapping scheme. Here, ELBA was applied to investigate the self-assembly processes of dodecyl-phosphocholine (DPC) micelle, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/1,2-dihexaoyl-sn-glycero-3-phosphocholine (DPPC/DHPC) bicelles, and DPPC/cyclohexane/water reverse micelles through coarse-grained molecular dynamics (MD) simulations. New parameters were obtained using a simplex algorithm-based calibration procedure to determine the Lennard-Jones parameters for cyclohexane, dodecane, and cyclohexane-dodecane cross-interactions. Density, self-diffusion coefficient, surface tension, and mixture excess volume were found to be in fair agreement with experimental data. These new parameters were used in the simulations, and the obtained structures were analyzed for shape, size, volume, and surface area. Except for the shape of DPC micelles, all other properties match well with available experimental data and all-atom simulations. Remarkably, in agreement with experiments the rodlike shape of the DPPC reverse micelle is well described by ELBA, while all-atom data in the literature predicts a disclike shape. To further check the consistency of the force field in reproducing the correct shapes of reverse micelles, additional simulations were performed doubling the system size. Two distinct reverse micelles were obtained both presenting the rodlike shape and correct aggregation number.
Collapse
Affiliation(s)
- R M de Souza
- Department of Chemistry , The University of Western Ontario , London , Ontario , Canada N6A 3K7.,Departamento de Química, FFCLRP , Universidade de São Paulo , Avenida Bandeirantes 3900 , 14040-901 Ribeirão Preto , SP , Brazil.,The Center for Advanced Materials and Biomaterials Research , The University of Western Ontario , London , Ontario , Canada N6K 3K7
| | - R H Ratochinski
- Departamento de Química, FFCLRP , Universidade de São Paulo , Avenida Bandeirantes 3900 , 14040-901 Ribeirão Preto , SP , Brazil
| | - Mikko Karttunen
- Department of Chemistry , The University of Western Ontario , London , Ontario , Canada N6A 3K7.,The Center for Advanced Materials and Biomaterials Research , The University of Western Ontario , London , Ontario , Canada N6K 3K7.,Department of Applied Mathematics , The University of Western Ontario , London , Ontario , Canada N6A 5B7
| | - L G Dias
- Departamento de Química, FFCLRP , Universidade de São Paulo , Avenida Bandeirantes 3900 , 14040-901 Ribeirão Preto , SP , Brazil
| |
Collapse
|
16
|
Tietz S, Leuenberger M, Höhner R, Olson AH, Fleming GR, Kirchhoff H. A proteoliposome-based system reveals how lipids control photosynthetic light harvesting. J Biol Chem 2020; 295:1857-1866. [PMID: 31929108 DOI: 10.1074/jbc.ra119.011707] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/09/2020] [Indexed: 11/06/2022] Open
Abstract
Integral membrane proteins are exposed to a complex and dynamic lipid environment modulated by nonbilayer lipids that can influence protein functions by lipid-protein interactions. The nonbilayer lipid monogalactosyldiacylglycerol (MGDG) is the most abundant lipid in plant photosynthetic thylakoid membranes, but its impact on the functionality of energy-converting membrane protein complexes is unknown. Here, we optimized a detergent-based reconstitution protocol to develop a proteoliposome technique that incorporates the major light-harvesting complex II (LHCII) into compositionally well-defined large unilamellar lipid bilayer vesicles to study the impact of MGDG on light harvesting by LHCII. Using steady-state fluorescence spectroscopy, CD spectroscopy, and time-correlated single-photon counting, we found that both chlorophyll fluorescence quantum yields and fluorescence lifetimes clearly indicate that the presence of MGDG in lipid bilayers switches LHCII from a light-harvesting to a more energy-quenching mode that dissipates harvested light into heat. It is hypothesized that in the in vitro system developed here, MGDG controls light harvesting of LHCII by modulating the hydrostatic lateral membrane pressure profile in the lipid bilayer sensed by LHCII-bound peripheral pigments.
Collapse
Affiliation(s)
- Stefanie Tietz
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, 99164-6340
| | - Michelle Leuenberger
- Department of Chemistry, University of California, Berkeley, California 94720; Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Ricarda Höhner
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, 99164-6340
| | - Alice H Olson
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, 99164-6340
| | - Graham R Fleming
- Department of Chemistry, University of California, Berkeley, California 94720; Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Helmut Kirchhoff
- Institute of Biological Chemistry, Washington State University, Pullman, Washington, 99164-6340.
| |
Collapse
|
17
|
Löffler PMG, Ries O, Vogel S. DNA-Mediated Liposome Fusion Observed by Fluorescence Spectrometry. Methods Mol Biol 2019; 2063:101-118. [PMID: 31667766 DOI: 10.1007/978-1-0716-0138-9_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
DNA-programmed and controlled fusion of lipid membranes have recently been optimized to reliably mix the contents between two populations of liposomes, each functionalized with complementary lipidated DNA (LiNA) oligomer. In this chapter we describe a procedure for DNA-controlled fusion of liposomes mediated by LiNAs that are designed to force bilayers into close proximity. Using a self-quenching fluorescent dye (Sulforhodamine B) to monitor both the mixing of the internal volumes and leakage of the dye into the outer volume we measure the efficiency of content mixing in the bulk population, allowing for direct comparison between different LiNA designs. By generating samples for calibration corresponding to different amounts of content mixing, the average number of fusion events per labeled liposome can be estimated.
Collapse
Affiliation(s)
- Philipp M G Löffler
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense M, Denmark
| | - Oliver Ries
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense M, Denmark
| | - Stefan Vogel
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Odense M, Denmark.
| |
Collapse
|
18
|
Rivera JL, Douglas JF. Reducing uncertainty in simulation estimates of the surface tension through a two-scale finite-size analysis: thicker is better. RSC Adv 2019; 9:35803-35812. [PMID: 35528077 PMCID: PMC9074429 DOI: 10.1039/c9ra07058c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 10/29/2019] [Indexed: 12/21/2022] Open
Abstract
Recent simulation studies of the surface tension γ, and other properties of thin free-standing films, have revealed unexpected finite size effects in which the variance of the properties vary monotonically with the in-plane width of the films, complicating the extrapolation of estimates of film properties to the thermodynamic limit. We carried out molecular dynamics simulations to determine the origin of this phenomenon, and to address the practical problem of developing a more reliable methodology for estimating γ in the thermodynamic limit. We find that there are two distinct finite size effects that must be addressed in a finite size analysis of γ in thin films. The first finite size scale is the in-plane width of the films and the second scale is the simulation cell size in the transverse direction. Increasing the first scale enhances fluctuations in γ, measured by the standard deviation of their distribution, while increasing the second reduces γ fluctuations due to a corresponding increased 'freedom' of the film to fluctuate out of plane. We find that using progressively large simulation cells in the transverse direction, while keeping the film width fixed to an extent in which the full bulk liquid zone is developed, allows us to obtain a smooth extrapolation to the thermodynamic limit, enabling a reduction of the γ uncertainty to a magnitude on the order of 1% for systems having a reasonably large size, i.e., O (1 μm).
Collapse
Affiliation(s)
- José L Rivera
- Laboratorio de Modelamiento y Simulación Molecular, Universidad Michoacana de San Nicolás de Hidalgo Morelia Michoacán 58000 Mexico
| | - Jack F Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology Gaithersburg Maryland 20899 USA
| |
Collapse
|
19
|
Shahane G, Ding W, Palaiokostas M, Azevedo HS, Orsi M. Interaction of Antimicrobial Lipopeptides with Bacterial Lipid Bilayers. J Membr Biol 2019; 252:317-329. [PMID: 31098677 PMCID: PMC6790193 DOI: 10.1007/s00232-019-00068-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 05/03/2019] [Indexed: 02/07/2023]
Abstract
The resistance of pathogens to traditional antibiotics is currently a global issue of enormous concern. As the discovery and development of new antibiotics become increasingly challenging, synthetic antimicrobial lipopeptides (AMLPs) are now receiving renewed attention as a new class of antimicrobial agents. In contrast to traditional antibiotics, AMLPs act by physically disrupting the cell membrane (rather than targeting specific proteins), thus reducing the risk of inducing bacterial resistance. In this study, we use microsecond-timescale atomistic molecular dynamics simulations to quantify the interaction of a short AMLP (C16-KKK) with model bacterial lipid bilayers. In particular, we investigate how fundamental transmembrane properties change in relation to a range of lipopeptide concentrations. A number of structural, mechanical, and dynamical features are found to be significantly altered in a non-linear fashion. At 10 mol% concentration, lipopeptides have a condensing effect on bacterial bilayers, characterized by a decrease in the area per lipid and an increase in the bilayer order. Higher AMLP concentrations of 25 and 40 mol% destabilize the membrane by disrupting the bilayer core structure, inducing membrane thinning and water leakage. Important transmembrane properties such as the lateral pressure and dipole potential profiles are also affected. Potential implications on membrane function and associated proteins are discussed.
Collapse
Affiliation(s)
- Ganesh Shahane
- Institute of Bioengineering, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Wei Ding
- School of Engineering & Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Michail Palaiokostas
- School of Engineering & Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Helena S Azevedo
- School of Engineering & Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Mario Orsi
- Department of Applied Sciences, University of the West of England, Coldharbour Lane, Bristol, BS16 1QY, UK.
| |
Collapse
|
20
|
Rivera JL, Douglas JF. Influence of film thickness on the stability of free-standing Lennard-Jones fluid films. J Chem Phys 2019; 150:144705. [DOI: 10.1063/1.5086284] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- José L. Rivera
- Laboratorio de Modelamiento y Simulación Molecular, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán 58000, Mexico
| | - Jack F. Douglas
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| |
Collapse
|
21
|
Mortezazadeh S, Jamali Y, Naderi-Manesh H, Lyubartsev AP. Implicit solvent systematic coarse-graining of dioleoylphosphatidylethanolamine lipids: From the inverted hexagonal to the bilayer structure. PLoS One 2019; 14:e0214673. [PMID: 30951539 PMCID: PMC6450619 DOI: 10.1371/journal.pone.0214673] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Accepted: 03/18/2019] [Indexed: 11/21/2022] Open
Abstract
Lamellar and hexagonal lipid structures are of particular importance in the biological processes such as membrane fusion and budding. Atomistic simulations of formation of these phases and transitions between them are computationally prohibitive, hence development of coarse-grained models is an important part of the methodological development in this area. Here we apply systematic bottom-up coarse-graining to model different phase structures formed by 1,2-dioleoylphosphatidylethanolamine (DOPE) lipid molecules. We started from atomistic simulations of DOPE lipids in water carried out at two different water/lipid molar ratio corresponding to the lamellar Lα and inverted hexagonal HII structures at low and high lipid concentrations respectively. The atomistic trajectories were mapped to coarse-grained trajectories, in which each lipid was represented by 14 coarse-grained sites. Then the inverse Monte Carlo method was used to compute the effective coarse-grained potentials which for the coarse-grain model reproduce the same structural properties as the atomistic simulations. The potentials derived from the low concentration atomistic simulation were only able to form a bilayer structure, while both Lα and HII lipid phases were formed in simulations with potentials obtained at high concentration. The typical atomistic configurations of lipids at high concentration combine fragments of both lamellar and non-lamellar structures, that is reflected in the extracted coarse-grained potentials which become transferable and can form a wide range of structures including the inverted hexagonal, bilayer, tubule, vesicle and micellar structures.
Collapse
Affiliation(s)
- Saeed Mortezazadeh
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
| | - Yousef Jamali
- Department of Mathematics, Tarbiat Modares University, Tehran, Iran
| | - Hossein Naderi-Manesh
- Department of Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran
- School of Biological Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran
- * E-mail: (HN); (APL)
| | - Alexander P. Lyubartsev
- Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, Stockholm, Sweden
- * E-mail: (HN); (APL)
| |
Collapse
|
22
|
Shahane G, Ding W, Palaiokostas M, Orsi M. Physical properties of model biological lipid bilayers: insights from all-atom molecular dynamics simulations. J Mol Model 2019; 25:76. [PMID: 30806797 DOI: 10.1007/s00894-019-3964-0] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 02/07/2019] [Indexed: 02/04/2023]
Abstract
The physical properties of lipid bilayers are sensitive to the specific type and composition of the lipids that make up the many different types of cell membranes. Studying model bilayers of representative heterogeneous compositions can provide key insights into membrane functionality. In this work, we use atomistic molecular dynamics simulations to characterize key properties in a number of bilayer membranes of varying composition. We first examine basic properties, such as lipid area, volume, and bilayer thickness, of simple, homogeneous bilayers comprising several lipid types, which are prevalent in biological membranes. Such lipids are then used in simulations of heterogeneous systems representative of bacterial, mammalian, and cancer membranes. Our analysis is especially focused on depth-dependent, transmembrane profiles; in particular, we calculate lateral pressure and dipole potential profiles, two fundamental properties which play key roles in a large number of biological functions.
Collapse
Affiliation(s)
- Ganesh Shahane
- Institute of Bioengineering, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Wei Ding
- School of Engineering & Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Michail Palaiokostas
- School of Engineering & Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS, UK
| | - Mario Orsi
- Department of Applied Sciences, University of the West of England, Coldharbour Lane, Bristol, BS16 1QY, UK.
| |
Collapse
|
23
|
Palaiokostas M, Ding W, Shahane G, Orsi M. Effects of lipid composition on membrane permeation. SOFT MATTER 2018; 14:8496-8508. [PMID: 30346462 DOI: 10.1039/c8sm01262h] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Passive permeation through lipid membranes is an essential process in biology. In vivo membranes typically consist of mixtures of lamellar and nonlamellar lipids. Lamellar lipids are characterized by their tendency to form lamellar sheet-like structures, which are predominant in nature. Nonlamellar lipids, when isolated, instead form more geometrically complex nonlamellar phases. While mixed lamellar/nonlamellar lipid membranes tend to adopt the ubiquitous lamellar bilayer structure, the presence of nonlamellar lipids is known to have profound effects on key membrane properties, such as internal distributions of stress and elastic properties, which in turn may alter related biological processes. This work focuses on one such process, i.e., permeation, by utilising atomistic molecular dynamics simulations in order to obtain transfer free energy profiles, diffusion profiles and permeation coefficients for a series of thirteen small molecules and drugs. Each permeant is tested on two bilayer membranes of different lipid composition, i.e., purely lamellar and mixed lamellar/nonlamellar. Our results indicate that the presence of nonlamellar lipids reduces permeation for smaller molecules (molecular weight < 100) but facilitates it for the largest ones (molecular weight > 100). This work represents an advancement towards the development of more realistic in silico permeability assays, which may have a substantial future impact in the area of rational drug design.
Collapse
Affiliation(s)
- Michail Palaiokostas
- School of Engineering and Materials Science, Queen Mary University of London, London, UK
| | | | | | | |
Collapse
|
24
|
Grillo DA, Albano JMR, Mocskos EE, Facelli JC, Pickholz M, Ferraro MB. Mechanical properties of drug loaded diblock copolymer bilayers: A molecular dynamics study. J Chem Phys 2018; 148:214901. [PMID: 29884038 DOI: 10.1063/1.5028377] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In this work, we present results of coarse-grained simulations to study the encapsulation of prilocaine (PLC), both neutral and protonated, on copolymer bilayers through molecular dynamics simulations. Using a previously validated membrane model, we have simulated loaded bilayers at different drug concentrations and at low (protonated PLC) and high (neutral PLC) pH levels. We have characterized key structural parameters of the loaded bilayers in order to understand the effects of encapsulation of PLC on the bilayer structure and mechanical properties. Neutral PLC was encapsulated in the hydrophobic region leading to a thickness increase, while the protonated species partitioned between the water phase and the poly(ethylene oxide)-poly(butadiene) (PBD) interface, relaxing the PBD region and leading to a decrease in the thickness. The tangential pressures of the studied systems were calculated, and their components were decomposed in order to gain insights on their compensation. In all cases, it is observed that the loading of the membrane does not significantly decrease the stability of the bilayer, indicating that the system could be used for drug delivery.
Collapse
Affiliation(s)
- Damián A Grillo
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Juan M R Albano
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Esteban E Mocskos
- Departamento de Computación, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Julio C Facelli
- Department of Biomedical Informatics, University of Utah, 421 Wakara Way, Suite 140, Salt Lake City, Utah 84108, USA
| | - Mónica Pickholz
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Marta B Ferraro
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| |
Collapse
|
25
|
Grasso G, Muscat S, Rebella M, Morbiducci U, Audenino A, Danani A, Deriu MA. Cell penetrating peptide modulation of membrane biomechanics by Molecular dynamics. J Biomech 2018; 73:137-144. [PMID: 29631749 DOI: 10.1016/j.jbiomech.2018.03.036] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 03/14/2018] [Accepted: 03/21/2018] [Indexed: 11/17/2022]
Abstract
The efficacy of a pharmaceutical treatment is often countered by the inadequate membrane permeability, that prevents drugs from reaching their specific intracellular targets. Cell penetrating peptides (CPPs) are able to route across cells' membrane various types of cargo, including drugs and nanoparticles. However, CPPs internalization mechanisms are not yet fully understood and depend on a wide variety of aspects. In this contest, the entry of a CPP into the lipid bilayer might induce molecular conformational changes, including marked variations on membrane's mechanical properties. Understanding how the CPP does influence the mechanical properties of cells membrane is crucial to design, engineer and improve new and existing penetrating peptides. Here, all atom Molecular Dynamics (MD) simulations were used to investigate the interaction between different types of CPPs embedded in a lipid bilayer of dioleoyl phosphatidylcholine (DOPC). In a greater detail, we systematically highlighted how CPP properties are responsible for modulating the membrane bending modulus. Our findings highlighted the CPP hydropathy strongly correlated with penetration of water molecules in the lipid bilayer, thus supporting the hypothesis that the amount of water each CPP can route inside the membrane is modulated by the hydrophobic and hydrophilic character of the peptide. Water penetration promoted by CPPs leads to a local decrease of the lipid order, which emerges macroscopically as a reduction of the membrane bending modulus.
Collapse
Affiliation(s)
- Gianvito Grasso
- Istituto Dalle Molle di Studi sull'Intelligenza Artificiale (IDSIA), Scuola universitaria professionale della Svizzera italiana (SUPSI), Università della Svizzera Italiana (USI), Centro Galleria 2, Manno CH-6928, Switzerland
| | - Stefano Muscat
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, IT-10128 Torino, Italy
| | - Martina Rebella
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, IT-10128 Torino, Italy
| | - Umberto Morbiducci
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, IT-10128 Torino, Italy
| | - Alberto Audenino
- Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, IT-10128 Torino, Italy
| | - Andrea Danani
- Istituto Dalle Molle di Studi sull'Intelligenza Artificiale (IDSIA), Scuola universitaria professionale della Svizzera italiana (SUPSI), Università della Svizzera Italiana (USI), Centro Galleria 2, Manno CH-6928, Switzerland
| | - Marco A Deriu
- Istituto Dalle Molle di Studi sull'Intelligenza Artificiale (IDSIA), Scuola universitaria professionale della Svizzera italiana (SUPSI), Università della Svizzera Italiana (USI), Centro Galleria 2, Manno CH-6928, Switzerland.
| |
Collapse
|
26
|
Rivera JL, Molina-Rodríguez L, Ramos-Estrada M, Navarro-Santos P, Lima E. Interfacial properties of the ionic liquid [bmim][triflate] over a wide range of temperatures. RSC Adv 2018; 8:10115-10123. [PMID: 35540813 PMCID: PMC9078723 DOI: 10.1039/c8ra00915e] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 02/26/2018] [Indexed: 12/25/2022] Open
Abstract
We carried out molecular dynamics simulations of the liquid/vacuum equilibrium of the ionic liquid [bmim][triflate] in a wide range of temperatures (323.15 to 573.15 K). The results showed liquid phases with high densities even at temperatures close to the decomposition temperature of the liquid. The density and surface tension behaviors are linear across this wide range of temperatures, which is an extension of the behaviors of these systems at low temperatures, where these properties have been experimentally measured. The interfacial region shows peaks of adsorption of the ions; they are ordered, with the alkyl chains of the [bmim] cations pointing out of the liquid, and the tailing angle of the chains becomes 90° at higher temperatures. The alkyl chains are part of the outermost interfacial region, where intra- and intermolecular tangential forces are in equilibrium; thus, they do not contribute to the total surface tension. Unlike simpler organic liquids, the surface tension is composed of positive normal contributions of intermolecular interactions; these are almost in equilibrium with the negative normal contributions of intramolecular interactions, which are mainly vibrations of the distance and the angle of valence. The pressure profiles show that the molecules are in 'crushed' conformations internally in the bulk liquid and even more so in the normal direction at the interface. The total pressure profiles show values with physical meaning, where the tangential peaks show higher values than normal pressures and give rise to the surface tension. Short cutoff radii for the calculation of intermolecular forces (less than 16.5 Å) produce a system that is not mechanically stable in the region of the bulk liquid (confirmed by radial distribution function calculations); this produces a difference between the normal pressure and the average of the tangential pressures, which affects the calculation of the surface tension due to overestimation by up to 20% when using the global expression, which is extensively used for the calculation of surface tension. The use of a sufficiently long cutoff radius avoids these mechanical balance problems.
Collapse
Affiliation(s)
- José L Rivera
- Graduate School of Physics Engineering, Universidad Michoacana de San Nicolás de Hidalgo Morelia C.P. 58000 Michoacán Mexico
- Faculty of Chemical Engineering, Universidad Michoacana de San Nicolás de Hidalgo Morelia C.P. 58000 Michoacán Mexico
| | - Luis Molina-Rodríguez
- Faculty of Chemical Engineering, Universidad Michoacana de San Nicolás de Hidalgo Morelia C.P. 58000 Michoacán Mexico
| | - Mariana Ramos-Estrada
- Faculty of Chemical Engineering, Universidad Michoacana de San Nicolás de Hidalgo Morelia C.P. 58000 Michoacán Mexico
| | - Pedro Navarro-Santos
- Institute of Chemical Biology Sciences, Universidad Michoacana de San Nicolás de Hidalgo Morelia C.P. 58000 Michoacán Mexico
| | - Enrique Lima
- Laboratorio de Fisicoquímica y Reactividad de Superficies (LaFReS), Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México Circuito Exterior S/N, CU, Del. Coyoacán Ciudad de México Mexico
| |
Collapse
|
27
|
Zhang T, Qiu Y, Luo Q, Zhao L, Yan X, Ding Q, Jiang H, Yang H. The Mechanism by Which Luteolin Disrupts the Cytoplasmic Membrane of Methicillin-Resistant Staphylococcus aureus. J Phys Chem B 2018; 122:1427-1438. [PMID: 29309144 DOI: 10.1021/acs.jpcb.7b05766] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most versatile human pathogens. Luteolin (LUT) has anti-MRSA activity by disrupting the MRSA cytoplasmic membrane. However, the mechanism by which luteolin disrupts the membrane remains unclear. Here, we performed differential scanning calorimetry (DSC) and all-atomic molecular dynamics (AA-MD) simulations to investigate the interactions and effects of LUT on model membranes composed of phosphatidylcholine (PC) and phosphatidylglycerol (PG). We detected the transition thermodynamic parameters of dipalmitoylphosphatidylcholine (DPPC) liposomes, dipalmitoylphosphatidylglycerol (DPPG) liposomes, and liposomes composed of both DPPC and DPPG at different LUT concentrations and showed that LUT molecules were located between polar heads and the hydrophobic region of DPPC/DPPG. In the MD trajectories, LUT molecules ranging from 5 to 50 had different effects on the membranes thickness, fluidity and ordered property of lipids, and lateral pressure of lipid bilayers composed of dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylglycerol (DOPG). Also, most LUT molecules were distributed in the region between the phosphorus atoms and C9 atoms of DOPC and DOPG. On the basis of the combination of these results, we conclude that the distinct effects of LUT on lipid bilayers composed of PCs and PGs may elucidate the mechanism by which LUT disrupts the cytoplasmic membrane of MRSA.
Collapse
Affiliation(s)
- Tao Zhang
- School of Pharmacy, East China University of Science and Technology , 130 Meilong Road, Shanghai 200237, China
| | - Yunguang Qiu
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , 555 Zuchongzhi Road, Shanghai 201203, China.,University of Chinese Academy of Sciences , No. 19A Yuquan Road, Beijing 100049, China
| | - Qichao Luo
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , 555 Zuchongzhi Road, Shanghai 201203, China.,University of Chinese Academy of Sciences , No. 19A Yuquan Road, Beijing 100049, China
| | - Lifen Zhao
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , 555 Zuchongzhi Road, Shanghai 201203, China
| | - Xin Yan
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , 555 Zuchongzhi Road, Shanghai 201203, China.,School of Life Science and Technology, ShanghaiTech University , 393 Huaxiazhong Road, Shanghai 201210, China
| | - Qiaoce Ding
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , 555 Zuchongzhi Road, Shanghai 201203, China
| | - Hualiang Jiang
- School of Pharmacy, East China University of Science and Technology , 130 Meilong Road, Shanghai 200237, China.,Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , 555 Zuchongzhi Road, Shanghai 201203, China.,University of Chinese Academy of Sciences , No. 19A Yuquan Road, Beijing 100049, China
| | - Huaiyu Yang
- Drug Discovery and Design Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , 555 Zuchongzhi Road, Shanghai 201203, China.,University of Chinese Academy of Sciences , No. 19A Yuquan Road, Beijing 100049, China
| |
Collapse
|
28
|
|
29
|
Sgouros AP, Vogiatzis GG, Kritikos G, Boziki A, Nikolakopoulou A, Liveris D, Theodorou DN. Molecular Simulations of Free and Graphite Capped Polyethylene Films: Estimation of the Interfacial Free Energies. Macromolecules 2017. [DOI: 10.1021/acs.macromol.7b01808] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- A. P. Sgouros
- School of Chemical Engineering, National Technical University of Athens (NTUA), GR-15780 Athens, Greece
| | - G. G. Vogiatzis
- School of Chemical Engineering, National Technical University of Athens (NTUA), GR-15780 Athens, Greece
| | - G. Kritikos
- School of Chemical Engineering, National Technical University of Athens (NTUA), GR-15780 Athens, Greece
| | - A. Boziki
- School of Chemical Engineering, National Technical University of Athens (NTUA), GR-15780 Athens, Greece
| | - A. Nikolakopoulou
- School of Chemical Engineering, National Technical University of Athens (NTUA), GR-15780 Athens, Greece
| | - D. Liveris
- School of Chemical Engineering, National Technical University of Athens (NTUA), GR-15780 Athens, Greece
| | - D. N. Theodorou
- School of Chemical Engineering, National Technical University of Athens (NTUA), GR-15780 Athens, Greece
| |
Collapse
|
30
|
Ding W, Palaiokostas M, Shahane G, Wang W, Orsi M. Effects of High Pressure on Phospholipid Bilayers. J Phys Chem B 2017; 121:9597-9606. [PMID: 28926699 DOI: 10.1021/acs.jpcb.7b07119] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The response of lipid membranes to changes in external pressure is important for many biological processes, and it can also be exploited for technological applications. In this work, we employ all-atom molecular dynamics simulations to characterize the changes in the physical properties of phospholipid bilayers brought about by high pressure (1000 bar). In particular, we study how the response differs, in relation to different chain unsaturation levels, by comparing monounsaturated 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC) and biunsaturated dioleoyl-phosphatidylcholine (DOPC) bilayers. Various structural, mechanical, and dynamical features are found to be altered by the pressure increase in both bilayers. Notably, for most properties, including bilayer area and thickness, lipid order parameters, lateral pressure profile, and curvature frustration energy, we observe significantly more pronounced effects for monounsaturated POPC than biunsaturated DOPC. Possible biological implications of the results obtained are discussed, especially in relation to how different lipids can control the structure and function of membrane proteins.
Collapse
Affiliation(s)
- Wei Ding
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London E1 4NS, U.K
| | - Michail Palaiokostas
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London E1 4NS, U.K
| | - Ganesh Shahane
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London E1 4NS, U.K
| | - Wen Wang
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London E1 4NS, U.K
| | - Mario Orsi
- Department of Applied Sciences, University of the West of England , Coldharbour Lane, Bristol BS16 1QY, U.K
| |
Collapse
|
31
|
Rodríguez-López T, Khalak Y, Karttunen M. Non-conformal coarse-grained potentials for water. J Chem Phys 2017; 147:134108. [DOI: 10.1063/1.4985914] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Affiliation(s)
- Tonalli Rodríguez-López
- Departamento de Física, Universidad Autónoma Metropolitana, Iztapalapa, Apdo 55 534, Mexico DF 09340, Mexico
- Department of Chemistry and Waterloo Institute of Nanotechnology, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L3G1, Canada
| | - Yuriy Khalak
- Department of Mathematics and Computer Science and Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, MetaForum, 5600 MB Eindhoven, The Netherlands
| | - Mikko Karttunen
- Department of Mathematics and Computer Science and Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, MetaForum, 5600 MB Eindhoven, The Netherlands
- Department of Chemistry, Western University, 1151 Richmond Street, London, Ontario N6A5B7, Canada
- Department of Applied Mathematics, Western University, 1151 Richmond Street, London, Ontario N6A5B7, Canada
| |
Collapse
|
32
|
Membrane Curvature and Lipid Composition Synergize To Regulate N-Ras Anchor Recruitment. Biophys J 2017; 113:1269-1279. [PMID: 28738989 DOI: 10.1016/j.bpj.2017.06.051] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Revised: 06/26/2017] [Accepted: 06/27/2017] [Indexed: 11/22/2022] Open
Abstract
Proteins anchored to membranes through covalently linked fatty acids and/or isoprenoid groups play crucial roles in all forms of life. Sorting and trafficking of lipidated proteins has traditionally been discussed in the context of partitioning to membrane domains of different lipid composition. We recently showed that membrane shape/curvature can in itself mediate the recruitment of lipidated proteins. However, exactly how membrane curvature and composition synergize remains largely unexplored. Here we investigated how three critical structural parameters of lipids, namely acyl chain saturation, headgroup size, and acyl chain length, modulate the capacity of membrane curvature to recruit lipidated proteins. As a model system we used the lipidated minimal membrane anchor of the GTPase, N-Ras (tN-Ras). Our data revealed complex synergistic effects, whereby tN-Ras binding was higher on planar DOPC than POPC membranes, but inversely higher on curved POPC than DOPC membranes. This variation in the binding to both planar and curved membranes leads to a net increase in the recruitment by membrane curvature of tN-Ras when reducing the acyl chain saturation state. Additionally, we found increased recruitment by membrane curvature of tN-Ras when substituting PC for PE, and when decreasing acyl chain length from 14 to 12 carbons (DMPC versus DLPC). However, these variations in recruitment ability had different origins, with the headgroup size primarily influencing tN-Ras binding to planar membranes whereas the change in acyl chain length primarily affected binding to curved membranes. Molecular field theory calculations recapitulated these findings and revealed lateral pressure as an underlying biophysical mechanism dictating how curvature and composition synergize to modulate recruitment of lipidated proteins. Our findings suggest that the different compositions of cellular compartments could modulate the potency of membrane curvature to recruit lipidated proteins and thereby synergistically regulate the trafficking and sorting of lipidated proteins.
Collapse
|
33
|
Schindler T, Kröner D, Steinhauser MO. On the dynamics of molecular self-assembly and the structural analysis of bilayer membranes using coarse-grained molecular dynamics simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1955-1963. [PMID: 27216316 DOI: 10.1016/j.bbamem.2016.05.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 03/27/2016] [Accepted: 05/17/2016] [Indexed: 12/11/2022]
Abstract
We present a molecular dynamics simulation study of the self-assembly of coarse-grained lipid molecules from unbiased random initial configurations. Our lipid model is based on a well-tried CG polymer model with an additional potential that mimics the hydrophobic properties of lipid tails. We find that several stages of self-organization of lipid clusters are involved in the dynamics of bilayer formation and that the resulting equilibrium structures sensitively depend on the strength of hydrophobic interactions hc of the lipid tails and on temperature T. The obtained stable lipid membranes are quantitatively analyzed with respect to their local structure and their degree of order. At equilibrium, we obtain self-stabilizing bilayer membrane structures that exhibit a bending stiffness κB and compression modulus KC comparable to experimental measurements under physiological conditions. We present a phase diagram of our lipid model which covers a sol-gel transition, a liquid (or gel-like) phase including stable bilayer structures and vesicle formation, as well as a quasi-crystalline phase. We also determine the exact conditions for temperature T and degree of hydrophobicity hc for stable bilayer formation including closed vesicles.
Collapse
Affiliation(s)
- Tanja Schindler
- Fraunhofer-Institute for High-Speed Dynamics, Ernst-Mach-Institut, EMI, Eckerstrasse 4, 79104 Freiburg, Germany; Albert-Ludwigs University of Freiburg, Department of Applied Mathematics, Hermann-Herder-Strasse 10, 79104 Freiburg, Germany
| | - Dietmar Kröner
- Albert-Ludwigs University of Freiburg, Department of Applied Mathematics, Hermann-Herder-Strasse 10, 79104 Freiburg, Germany
| | - Martin O Steinhauser
- Fraunhofer-Institute for High-Speed Dynamics, Ernst-Mach-Institut, EMI, Eckerstrasse 4, 79104 Freiburg, Germany; Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland.
| |
Collapse
|
34
|
Hills RD, McGlinchey N. Model parameters for simulation of physiological lipids. J Comput Chem 2016; 37:1112-8. [PMID: 26864972 PMCID: PMC5067697 DOI: 10.1002/jcc.24324] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 12/19/2015] [Accepted: 01/17/2016] [Indexed: 12/16/2022]
Abstract
Coarse grain simulation of proteins in their physiological membrane environment can offer insight across timescales, but requires a comprehensive force field. Parameters are explored for multicomponent bilayers composed of unsaturated lipids DOPC and DOPE, mixed-chain saturation POPC and POPE, and anionic lipids found in bacteria: POPG and cardiolipin. A nonbond representation obtained from multiscale force matching is adapted for these lipids and combined with an improved bonding description of cholesterol. Equilibrating the area per lipid yields robust bilayer simulations and properties for common lipid mixtures with the exception of pure DOPE, which has a known tendency to form nonlamellar phase. The models maintain consistency with an existing lipid-protein interaction model, making the force field of general utility for studying membrane proteins in physiologically representative bilayers.
Collapse
Affiliation(s)
- Ronald D Hills
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New England, 716 Stevens Ave, Portland, Maine, 04103
| | - Nicholas McGlinchey
- Department of Pharmaceutical Sciences, College of Pharmacy, University of New England, 716 Stevens Ave, Portland, Maine, 04103
| |
Collapse
|
35
|
Siani P, de Souza RM, Dias LG, Itri R, Khandelia H. An overview of molecular dynamics simulations of oxidized lipid systems, with a comparison of ELBA and MARTINI force fields for coarse grained lipid simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2498-2511. [PMID: 27058982 DOI: 10.1016/j.bbamem.2016.03.031] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 03/23/2016] [Accepted: 03/24/2016] [Indexed: 11/29/2022]
Abstract
Biological membranes and model lipid systems containing high amounts of unsaturated lipids and sterols are subject to chemical and/or photo-induced lipid oxidation, which leads to the creation of exotic oxidized lipid products (OxPLs). OxPLs are known to have significant physiological impact in cellular systems and also affect physical properties of both biological and model lipid bilayers. In this paper we (i) provide a perspective on the existing literature on simulations of lipid bilayer systems containing oxidized lipid species as well as the main related experimental results, (ii) describe our new data of all-atom and coarse-grained simulations of hydroperoxidized lipid monolayer and bilayer systems and (iii) provide a comparison of the MARTINI and ELBA coarse grained force fields for lipid bilayer systems. We show that the better electrostatic treatment of interactions in ELBA is able to resolve previous conflicts between experiments and simulations. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.
Collapse
Affiliation(s)
- P Siani
- MEMPHYS-Center for Biomembrane Physics, Department of Physics and Chemistry, University of Southern, Denmark; Departamento de Química, FFCLRP, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - R M de Souza
- Departamento de Química, FFCLRP, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - L G Dias
- Departamento de Química, FFCLRP, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - R Itri
- Departamento de Física Aplicada, Instituto de Física, Universidade de São Paulo, São Paulo, SP, Brazil
| | - H Khandelia
- MEMPHYS-Center for Biomembrane Physics, Department of Physics and Chemistry, University of Southern, Denmark.
| |
Collapse
|
36
|
Purushothaman S, Cama J, Keyser UF. Dependence of norfloxacin diffusion across bilayers on lipid composition. SOFT MATTER 2016; 12:2135-2144. [PMID: 26768751 DOI: 10.1039/c5sm02371h] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Antibiotic resistance is a growing concern in medicine and raises the need to develop and design new drug molecules that can efficiently inhibit bacterial replication. Spurring the passive uptake of the drug molecules is an obvious solution. However our limited understanding of drug-membrane interactions due to the presence of an overwhelming variety of lipids constituting cellular membranes and the lack of facile tools to probe the bio-physical interactions between drugs and lipids imposes a major challenge towards developing new drug molecules that can enter the cell via passive diffusion. Here, we used a label-free micro-fluidic platform combined with giant unilamellar lipid vesicles to investigate the permeability of membranes containing mixtures of DOPE and DOPG in DOPC, leading to a label-free measurement of passive membrane-permeability of autofluorescent antibiotics. A fluoroquinolone drug, norfloxacin was used as a case study. Our results indicate that the diffusion of norfloxacin is strongly dependent on the lipid composition which is not expected from the traditional octanol-lipid partition co-efficient assay. The anionic lipid, DOPG, slows the diffusion process whereas the diffusion across liposomes containing DOPE increases with higher DOPE concentration. Our findings emphasise the need to investigate drug-membrane interactions with focus on the specificity of drugs to lipids for efficient drug delivery, drug encapsulation and targeted drug-delivery.
Collapse
Affiliation(s)
- Sowmya Purushothaman
- Biological and Soft Systems, Department of Physics, University of Cambridge, Cavendish Laboratory, JJ Thomson Avenue, Cambridge, CB3 0HE, UK.
| | | | | |
Collapse
|
37
|
Genheden S. Predicting Partition Coefficients with a Simple All-Atom/Coarse-Grained Hybrid Model. J Chem Theory Comput 2015; 12:297-304. [PMID: 26592737 DOI: 10.1021/acs.jctc.5b00963] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The solvation free energy is an essential quantity in force field development and in numerous applications. Here, we present the estimation of solvation free energies in polar (water, hexanol, octanol, and nonanol) and in apolar (hexane, octane, and nonane) media. The estimates are produced using molecular dynamics simulations employing a simple all-atom/coarse-grained hybrid model (AA/ELBA) and are therefore very efficient. More than 150 solutes were taken from the Minnesota solvation database and represent small, organic molecules. The mean absolute deviation for the different solvents ranges between 2.0 and 4.1 kJ/mol, and the correlation coefficient ranges between 0.78 and 0.99, indicating that the predictions are accurate. Outliers are identified, and potential avenues for improvements are discussed. Furthermore, partition coefficients between water and the organic solvents were estimated, and the percentage of the predictions that has the correct sign ranges between 74% (for octane) and 92% (for octanol and hexanol). Finally, membrane/water partition coefficients are replaced with hexane/water and octanol/water partition coefficients, and the latter is found to be as accurate as the expensive membrane calculations, indicating a wider application area.
Collapse
Affiliation(s)
- Samuel Genheden
- Department of Chemistry and Molecular Biology, University of Gothenburg , Box 462, SE-405 30 Göteborg, Sweden
| |
Collapse
|
38
|
Ding W, Palaiokostas M, Wang W, Orsi M. Effects of Lipid Composition on Bilayer Membranes Quantified by All-Atom Molecular Dynamics. J Phys Chem B 2015; 119:15263-74. [PMID: 26560961 DOI: 10.1021/acs.jpcb.5b06604] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Biological bilayer membranes typically contain varying amounts of lamellar and nonlamellar lipids. Lamellar lipids, such as dioleoylphosphatidylcholine (DOPC), are defined by their tendency to form the lamellar phase, ubiquitous in biology. Nonlamellar lipids, such as dioleoylphosphatidylethanolamine (DOPE), prefer instead to form nonlamellar phases, which are mostly nonbiological. However, nonlamellar lipids mix with lamellar lipids in biomembrane structures that remain overall lamellar. Importantly, changes in the lamellar vs nonlamellar lipid composition are believed to affect membrane function and modulate membrane proteins. In this work, we employ atomistic molecular dynamics simulations to quantify how a range of bilayer properties are altered by variations in the lamellar vs nonlamellar lipid composition. Specifically, we simulate five DOPC/DOPE bilayers at mixing ratios of 1/0, 3/1, 1/1, 1/3, and 0/1. We examine properties including lipid area and bilayer thickness, as well as the transmembrane profiles of electron density, lateral pressure, electric field, and dipole potential. While the bilayer structure is only marginally altered by lipid composition changes, dramatic effects are observed for the lateral pressure, electric field, and dipole potential profiles. Possible implications for membrane function are discussed.
Collapse
Affiliation(s)
- Wei Ding
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London, E1 4NS, U.K
| | - Michail Palaiokostas
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London, E1 4NS, U.K
| | - Wen Wang
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London, E1 4NS, U.K
| | - Mario Orsi
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London, E1 4NS, U.K
| |
Collapse
|
39
|
Genheden S, Essex JW. A simple and transferable all-atom/coarse-grained hybrid model to study membrane processes. J Chem Theory Comput 2015; 11:4749-59. [PMID: 26574264 DOI: 10.1021/acs.jctc.5b00469] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We present an efficient all-atom/coarse-grained hybrid model and apply it to membrane processes. This model is an extension of the all-atom/ELBA model applied previously to processes in water. Here, we improve the efficiency of the model by implementing a multiple-time step integrator that allows the atoms and the coarse-grained beads to be propagated at different timesteps. Furthermore, we fine-tune the interaction between the atoms and the coarse-grained beads by computing the potential of mean force of amino acid side chain analogs along the membrane normal and comparing to atomistic simulations. The model was independently validated on the calculation of small-molecule partition coefficients. Finally, we apply the model to membrane peptides. We studied the tilt angle of the Walp23 and Kalp23 helices in two different model membranes and the stability of the glycophorin A dimer. The model is efficient, accurate, and straightforward to use, as it does not require any extra interaction particles, layers of atomistic solvent molecules or tabulated potentials, thus offering a novel, simple approach to study membrane processes.
Collapse
Affiliation(s)
- Samuel Genheden
- School of Chemistry, University of Southampton, Highfield , SO17 1BJ, Southampton, United Kingdom
| | - Jonathan W Essex
- School of Chemistry, University of Southampton, Highfield , SO17 1BJ, Southampton, United Kingdom
| |
Collapse
|
40
|
Baczynski K, Markiewicz M, Pasenkiewicz-Gierula M. A computer model of a polyunsaturated monogalactolipid bilayer. Biochimie 2015; 118:129-40. [PMID: 26348551 DOI: 10.1016/j.biochi.2015.09.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 09/02/2015] [Indexed: 12/21/2022]
Abstract
1,2-di-O-acyl-3-O-β-D-galactopyranosyl-sn-glycerol (MGDG) is the main lipid component of thylakoid membranes of higher plants and algae. This monogalactolipid is thought of as a non-bilayer lipid but actually it can form both lamellar and nonlamellar phases. In this study, molecular dynamics (MD) simulations of the fully hydrated di-18:3 MGDG bilayer in the lamellar phase were carried out at 310 and 295 K for 200 and 450 ns, respectively, using the GROMACS 4 software package and OPLS-AA force field. At both temperatures, the lamellar phase of the systems was stable. The pure di-18:3 MGDG bilayer is the first step towards creating a computer model of the lipid matrix of the thylakoid membrane and the main aim of this study was to validate the computer model of di-18:3 MGDG in the bilayer and also to assess the properties of the bilayer. However, only a few of the predicted properties could be compared with those derived experimentally and in other MD simulations because of insufficient amount of such data. Thus, direct validation of the MGDG bilayer proved difficult. Therefore, in the validation process also an indirect approach was used, in which a computer model of the 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) bilayer simulated at the same temperatures using the same force field as the MGDG bilayer was assessed. Successful validation of the DOPC bilayer parameterized in the OPLS-AA force field and similar properties of the MGDG molecules in the pure 18:3 MGDG and in binary 18:3 MGDG-PC bilayers indicate that the computer model of the MDGD molecule is faithful and the MGDG bilayer is representative on the time scales covered in these MD simulations.
Collapse
Affiliation(s)
- Krzysztof Baczynski
- Department of Computational Biophysics and Bioinformatics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Michal Markiewicz
- Department of Computational Biophysics and Bioinformatics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Marta Pasenkiewicz-Gierula
- Department of Computational Biophysics and Bioinformatics, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland; Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland.
| |
Collapse
|
41
|
|
42
|
Bejagam KK, Balasubramanian S. Supramolecular Polymerization: A Coarse Grained Molecular Dynamics Study. J Phys Chem B 2015; 119:5738-46. [DOI: 10.1021/acs.jpcb.5b01655] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Karteek K. Bejagam
- Chemistry and Physics of
Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
| | - Sundaram Balasubramanian
- Chemistry and Physics of
Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
| |
Collapse
|
43
|
Barriga HMG, Bazin R, Templer RH, Law RV, Ces O. Buffer-induced swelling and vesicle budding in binary lipid mixtures of dioleoylphosphatidylcholine:dioleoylphosphatidylethanolamine and dioleoylphosphatidylcholine:lysophosphatidylcholine using small-angle X-ray scattering and ³¹P static NMR. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:2979-2987. [PMID: 25738977 DOI: 10.1021/la5047996] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
A large variety of data exists on lipid phase behavior; however, it is mostly in nonbuffered systems over nonbiological temperature ranges. We present biophysical data on lipid mixtures of dioleoylphosphatidylcholine (DOPC), dioleoylphosphatidylethanolamine (DOPE), and lysophosphatidylcholine (LysoPC) examining their behaviors in excess water and buffer systems over the temperature range 4-34 °C. These mixtures are commonly used to investigate the effects of spontaneous curvature on integral membrane proteins. Using small-angle X-ray scattering (SAXS) and (31)P NMR, we observed lamellar and vesicle phases, with the buffer causing an increase in the layer spacing. Increasing amounts of DOPE in a DOPC bilayer decreased the layer spacing of the mesophase, while the opposite trend was observed for increasing amounts of LysoPC. (31)P static NMR was used to analyze the DOPC:LysoPC samples to investigate the vesicle sizes present, with evidence of vesicle budding observed at LysoPC concentrations above 30 mol %. NMR line shapes were fitted using an adapted program accounting for the distortion of the lipids within the magnetic field. The distortion of the vesicle, because of magnetic susceptibility, varied with LysoPC content, and a discontinuity was found in both the water and buffer samples. Generally, the distortion increased with LysoPC content; however, at a ratio of DOPC:LysoPC 60:40, the sample showed a level of distortion of the vesicle similar to that of pure DOPC. This implies an increased flexibility in the membrane at this point. Commonly, the assumption is that for increasing LysoPC concentration there is a reduction in membrane tension, implying that estimations of membrane tension based on spontaneous curvature assumptions may not be accurate.
Collapse
Affiliation(s)
- Hanna M G Barriga
- †Department of Chemistry, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Richard Bazin
- ‡Pfizer Global Research and Development, Sandwich, Kent CT13 9NJ, United Kingdom
| | - Richard H Templer
- †Department of Chemistry, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Robert V Law
- †Department of Chemistry, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Oscar Ces
- †Department of Chemistry, Imperial College London, London, SW7 2AZ, United Kingdom
| |
Collapse
|
44
|
Monteiro M, Raiado-Pereira L, Prazeres D, Mateus M. Preparation of liposome membrane adsorbers and testing for plasmid purification. Biochem Eng J 2015. [DOI: 10.1016/j.bej.2014.09.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
|
45
|
|
46
|
Calculation and visualization of atomistic mechanical stresses in nanomaterials and biomolecules. PLoS One 2014; 9:e113119. [PMID: 25503996 PMCID: PMC4263534 DOI: 10.1371/journal.pone.0113119] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 10/23/2014] [Indexed: 11/19/2022] Open
Abstract
Many biomolecules have machine-like functions, and accordingly are discussed in terms of mechanical properties like force and motion. However, the concept of stress, a mechanical property that is of fundamental importance in the study of macroscopic mechanics, is not commonly applied in the biomolecular context. We anticipate that microscopical stress analyses of biomolecules and nanomaterials will provide useful mechanistic insights and help guide molecular design. To enable such applications, we have developed Calculator of Atomistic Mechanical Stress (CAMS), an open-source software package for computing atomic resolution stresses from molecular dynamics (MD) simulations. The software also enables decomposition of stress into contributions from bonded, nonbonded and Generalized Born potential terms. CAMS reads GROMACS topology and trajectory files, which are easily generated from AMBER files as well; and time-varying stresses may be animated and visualized in the VMD viewer. Here, we review relevant theory and present illustrative applications.
Collapse
|
47
|
Orsi M. Molecular dynamics simulation of humic substances. CHEMICAL AND BIOLOGICAL TECHNOLOGIES IN AGRICULTURE 2014; 1:10. [DOI: 10.1186/s40538-014-0010-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
|
48
|
Johnson JC, Korley LTJ, Tsige M. Coarse-Grained Modeling of Peptidic/PDMS Triblock Morphology. J Phys Chem B 2014; 118:13718-28. [DOI: 10.1021/jp506553v] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- J. Casey Johnson
- Department
of Macromolecular Science and Engineering, Case Western Reserve University, 2100 Adelbert Road, Cleveland, Ohio 44106, United States
| | - LaShanda T. J. Korley
- Department
of Macromolecular Science and Engineering, Case Western Reserve University, 2100 Adelbert Road, Cleveland, Ohio 44106, United States
| | - Mesfin Tsige
- Department of Polymer Science, The University of Akron, Goodyear Polymer Center 1021, Akron, Ohio 44325, United States
| |
Collapse
|
49
|
Orsi M, Ding W, Palaiokostas M. Direct Mixing of Atomistic Solutes and Coarse-Grained Water. J Chem Theory Comput 2014; 10:4684-93. [PMID: 26588159 DOI: 10.1021/ct500065k] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present a new dual-resolution approach for coupling atomistic and coarse-grained models in molecular dynamics simulations of hydrated systems. In particular, a coarse-grained point dipolar water model is used to solvate molecules represented with standard all-atom force fields. A unique characteristic of our methodology is that the mixing of resolutions is direct, meaning that no additional or ad hoc scaling factors, intermediate regions, or extra sites are required. To validate the methodology, we compute the hydration free energy of 14 atomistic small molecules (analogs of amino acid side chains) solvated by the coarse-grained water. Remarkably, our predictions reproduce the experimental data as accurately as the predictions from state-of-the-art fully atomistic simulations. We also show that the hydration free energy of the coarse-grained water itself is in comparable or better agreement with the experimental value than the predictions from all but one of the most common multisite atomistic models. The coarse-grained water is then applied to solvate a typical atomistic protein containing both α-helix and β-strand elements. Moreover, parallel tempering simulations are performed to investigate the folding free energy landscape of a representative α helical and a β hairpin structure. For the simulations considered in this work, our dual-resolution method is found to be 3 to 6 times more computationally efficient than corresponding fully atomistic approaches.
Collapse
Affiliation(s)
- Mario Orsi
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London E1 4NS, United Kingdom
| | - Wei Ding
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London E1 4NS, United Kingdom
| | - Michail Palaiokostas
- School of Engineering & Materials Science, Queen Mary University of London , Mile End Road, London E1 4NS, United Kingdom
| |
Collapse
|
50
|
Preclinical development and ocular biodistribution of gemini-DNA nanoparticles after intravitreal and topical administration: towards non-invasive glaucoma gene therapy. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2014; 10:1637-47. [PMID: 24905400 DOI: 10.1016/j.nano.2014.05.010] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 04/16/2014] [Accepted: 05/14/2014] [Indexed: 11/20/2022]
Abstract
UNLABELLED Gene therapy could offer improvement in the treatment of glaucoma compared to the current standard of lowering intraocular pressure. We have developed and characterized non-viral gemini surfactant-phospholipid nanoparticles (GL-NPs) for intravitreal and topical administration. Optimized GL-NPs (size range 150-180 nm) were biocompatible with rat retinal ganglion (RGC-5) cells with >95% viability by PrestoBlue™ assay. GL-NPs carrying Cy5-labeled plasmid DNA demonstrated distinct trafficking behavior and biodisposition within the eye in vivo after intravitreal or topical application with respect to pathways of movement and physicochemical stability. After intravitreal injection in mice, GL-NPs localized within the nerve fiber layer of the retina, whereas after topical application, GL-NPs were located in several anterior chamber tissues, including the limbus, iris and conjunctiva. GL-NPs were thermodynamically stable in the vitreous and tear fluid and were trafficked as single, non-aggregated particles after both types of administration. FROM THE CLINICAL EDITOR In this paper, the development and characterization of non-viral gemini surfactant-phospholipid nanoparticles is reported with the goal of establishing a gene delivery system that addresses glaucoma in a non-invasive fashion. The authors found that after topical application, the concentration of these nanoparticles was higher in anterior chamber-related components of the eye, whereas intra-vitreal administration resulted in accumulation in the retinal nerve fibre layer.
Collapse
|