201
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Pannuzzo M, McDargh ZA, Deserno M. The role of scaffold reshaping and disassembly in dynamin driven membrane fission. eLife 2018; 7:39441. [PMID: 30561335 PMCID: PMC6355196 DOI: 10.7554/elife.39441] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 12/13/2018] [Indexed: 12/11/2022] Open
Abstract
The large GTPase dynamin catalyzes membrane fission in eukaryotic cells, but despite three decades of experimental work, competing and partially conflicting models persist regarding some of its most basic actions. Here we investigate the mechanical and functional consequences of dynamin scaffold shape changes and disassembly with the help of a geometrically and elastically realistic simulation model of helical dynamin-membrane complexes. Beyond changes of radius and pitch, we emphasize the crucial role of a third functional motion: an effective rotation of the filament around its longitudinal axis, which reflects alternate tilting of dynamin’s PH binding domains and creates a membrane torque. We also show that helix elongation impedes fission, hemifission is reached via a small transient pore, and coat disassembly assists fission. Our results have several testable structural consequences and help to reconcile mutual conflicting aspects between the two main present models of dynamin fission—the two-stage and the constrictase model. When cells take up material from their surroundings, they must first transport this cargo across their outer membrane, a flexible sheet of tightly organized fat molecules that act as a barrier to the environment. Cells can achieve this by letting their membrane surround the object, pulling it inwards until it is contained in a pouch that bulges into the cell. This bag is then corded up so it splits off from the outer membrane. The ‘cord’ is a protein called dynamin, which is thought to form a tight spiral around the bag’s neck, closing it over and pinching it away. The structure of dynamin is fairly well known, and yet several theories compete to explain how it may snap the bag off the outer membrane. Here, Pannuzzo et al. have created a computer simulation that faithfully replicates the geometry and the elasticity of the membrane and of dynamin, and used it to test different ways the protein could work. The first test featured simple constriction, where the dynamin spiral contracts around the membrane to pinch it; this only separated the bag from the membrane after implausibly tight constriction. The second test added elongation, with the spiral lengthening as well as reducing its diameter, but this further reduced the ability for the protein to snap off the membrane. The final test combined constriction and rotation, whereby dynamin ‘twirls’ as it presses on the neck of the bag: this succeeded in efficiently severing the membrane once the dynamin spiral disassembled. Indeed, the simulations suggested that dynamin might start to dismantle while it constricts, without compromising its role. In fact, getting rid of excess length as the protein contracts helps to dissolve any remnants of a membrane connection. Defects in dynamin are associated with conditions such as centronuclear myopathy and Charcot‐Marie‐Tooth peripheral neuropathy. Recent research also indicates that the protein is involved in a much wider range of neurological disorders that include Alzheimer's, Parkinson's, Huntington's, and amyotrophic lateral sclerosis. The models created by Pannuzzo et al. are useful tools to understand how dynamin and similar proteins work and sometimes fail.
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Affiliation(s)
- Martina Pannuzzo
- Department of Physics, Carnegie Mellon University, Pittsburgh, United States
| | - Zachary A McDargh
- Department of Physics, Carnegie Mellon University, Pittsburgh, United States
| | - Markus Deserno
- Department of Physics, Carnegie Mellon University, Pittsburgh, United States
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202
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Liu L, Zhang S, Zhao L, Gu Z, Duan G, Zhou B, Yang Z, Zhou R. Superior Compatibility of C 2 N with Human Red Blood Cell Membranes and the Underlying Mechanism. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1803509. [PMID: 30474237 DOI: 10.1002/smll.201803509] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 10/28/2018] [Indexed: 06/09/2023]
Abstract
The widespread use of nanomaterials, such as carbon based 2D nanomaterials, in biomedical applications, has been accompanied by a growing concern on their biocompatibility, and in particular, on how they may affect the integrity of cell membranes. Herein, the interactions between C2 N, a novel 2D nanomaterial, and human red blood cell membranes are explored using a combined experimental and theoretical approach. The experimental microscopies show that C2 N exerts a negligible hemolysis effect on the blood cells with a superior compatibility to their cell membranes, when compared with the control system, reduced graphene oxide (rGO), which is found to be highly hemolytic. The molecular dynamics simulations further reveal the underlying molecular mechanisms, which indicate that C2 N prefers to be adsorbed flat on the water-membrane interface. Interaction energy analyses demonstrate the crucial role of Coulombic contributions, originating from the unique electrostatic potential surface of C2 N, in preventing C2 N from penetrating into cell membranes. These findings indicate a high compatibility of C2 N with cell membranes, which may provide useful foundation for the future exploration of this 2D nanomaterial in related biomedical applications.
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Affiliation(s)
- Lu Liu
- Institute of Quantitative Biology and Medicine, State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Jiangsu, 215123, China
| | - Shitong Zhang
- Institute of Quantitative Biology and Medicine, State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Jiangsu, 215123, China
| | - Lin Zhao
- Institute of Quantitative Biology and Medicine, State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Jiangsu, 215123, China
| | - Zonglin Gu
- Institute of Quantitative Biology and Medicine, State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Jiangsu, 215123, China
| | - Guangxin Duan
- Institute of Quantitative Biology and Medicine, State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Jiangsu, 215123, China
| | - Bo Zhou
- School of Electronic Engineering, Chengdu Technological University, Chengdu, 611730, China
| | - Zaixing Yang
- Institute of Quantitative Biology and Medicine, State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Jiangsu, 215123, China
| | - Ruhong Zhou
- Institute of Quantitative Biology and Medicine, State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Soochow University, Jiangsu, 215123, China
- IBM Thomas J. Watson Research Center, Yorktown Heights, NY, 10598, USA
- Department of Chemistry, Columbia University, New York, NY, 10027, USA
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203
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Werner S, Ebenhan J, Haupt C, Bacia K. A Quantitative and Reliable Calibration Standard for Dual-Color Fluorescence Cross-Correlation Spectroscopy. Chemphyschem 2018; 19:3436-3444. [PMID: 30489002 DOI: 10.1002/cphc.201800576] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 10/29/2018] [Indexed: 11/06/2022]
Abstract
Dual-color Fluorescence Cross-Correlation Spectroscopy (dcFCCS) allows binding analysis of biomolecules. Combining cross- and autocorrelation amplitudes yields binding degrees and concentrations of bound and unbound species. However, non-ideal detection volume overlap reduces the cross-correlation, causing overestimation of the Kd . The overlap quality factor that relates measured and true cross-correlation amplitudes has been difficult to determine, because neither a perfect 1 : 1 labeled sample nor perfectly overlapping volumes are readily accomplished. Here, we describe how a stochastically labeled sample can be used for quantitative calibration. Lipid vesicles doped with green and red fluorescent dyes yield highly reproducible relative cross-correlations and allow determination of the setup-dependent overlap quality factor. This reliable, affordable and quick-to-prepare calibration standard expedites any quantitative co-localization or binding analysis by dcFCCS.
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Affiliation(s)
- Stefan Werner
- Institute of Chemistry, ZIK HALOmem and Charles-Tanford-Protein Center, University of Halle, Kurt-Mothes-Str. 3a, 06120, Halle, Germany
| | - Jan Ebenhan
- Institute of Chemistry, ZIK HALOmem and Charles-Tanford-Protein Center, University of Halle, Kurt-Mothes-Str. 3a, 06120, Halle, Germany
| | - Caroline Haupt
- Institute of Chemistry, ZIK HALOmem and Charles-Tanford-Protein Center, University of Halle, Kurt-Mothes-Str. 3a, 06120, Halle, Germany
| | - Kirsten Bacia
- Institute of Chemistry, ZIK HALOmem and Charles-Tanford-Protein Center, University of Halle, Kurt-Mothes-Str. 3a, 06120, Halle, Germany
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204
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Vitkova V, Mitkova D, Antonova K, Popkirov G, Dimova R. Sucrose solutions alter the electric capacitance and dielectric permittivity of lipid bilayers. Colloids Surf A Physicochem Eng Asp 2018. [DOI: 10.1016/j.colsurfa.2018.05.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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205
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206
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Ferhan AR, Špačková B, Jackman JA, Ma GJ, Sut TN, Homola J, Cho NJ. Nanoplasmonic Ruler for Measuring Separation Distance between Supported Lipid Bilayers and Oxide Surfaces. Anal Chem 2018; 90:12503-12511. [DOI: 10.1021/acs.analchem.8b02222] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Abdul Rahim Ferhan
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue 639798, Singapore
| | - Barbora Špačková
- Institute of Photonics and Electronics, Czech Academy of Science, Chaberská 57, Prague 8 18251, Czech Republic
| | - Joshua A. Jackman
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue 639798, Singapore
| | - Gamaliel J. Ma
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue 639798, Singapore
| | - Tun Naw Sut
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue 639798, Singapore
| | - Jiří Homola
- Institute of Photonics and Electronics, Czech Academy of Science, Chaberská 57, Prague 8 18251, Czech Republic
| | - Nam-Joon Cho
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue 639798, Singapore
- School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive 637459, Singapore
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207
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Nademi Y, Tang T, Uludağ H. Steered molecular dynamics simulations reveal a self-protecting configuration of nanoparticles during membrane penetration. NANOSCALE 2018; 10:17671-17682. [PMID: 30206609 DOI: 10.1039/c8nr04287j] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Cell entry of polynucleotide-based therapeutic agents can be facilitated by nanoparticle (NP) mediated delivery. In this work, using steered molecular dynamics simulations, we simulated the membrane penetration process of a NP formed by 2 short interfering RNA (siRNA) and 6 polyethylenimine (PEI) molecules. To the best of our knowledge, this is the first set of simulations that explore the direct penetration of an siRNA/PEI NP through a membrane at an all-atom scale. Three types of PEI molecules were used for NP formation: a native PEI, a PEI modified with caprylic acids and a PEI modified with linoleic acids. We found that hydrogen bond formation between the PEIs and the membrane did not lead to instability of the siRNA/PEI NPs during the internalization process. Instead, our results suggested adoption of a "self-protecting" configuration by the siRNA/PEI NP during membrane penetration, where the siRNA/PEI NP becomes more compact and siRNAs become aligned, leading to more stable configurations while detaching from the membrane. The siRNA/PEI NP modified with linoleic acid showed the smallest structural change due to its strong intra-particle lipid associations and the resulting rigidity, while NP modified with caprylic acid showed the largest structural changes. Our observations provide unique insight into the structural changes of siRNA/PEI NPs when crossing the cell membrane, which can be important for the design of new NP carriers for nucleic acid delivery.
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Affiliation(s)
- Yousef Nademi
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Canada.
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208
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Selvam B, Mittal S, Shukla D. Free Energy Landscape of the Complete Transport Cycle in a Key Bacterial Transporter. ACS CENTRAL SCIENCE 2018; 4:1146-1154. [PMID: 30276247 PMCID: PMC6161048 DOI: 10.1021/acscentsci.8b00330] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Indexed: 05/21/2023]
Abstract
PepTSo is a proton-coupled bacterial symporter, from the major facilitator superfamily (MFS), which transports di-/tripeptide molecules. The recently obtained crystal structure of PepTSo provides an unprecedented opportunity to gain an understanding of functional insights of the substrate transport mechanism. Binding of the proton and peptide molecule induces conformational changes into occluded (OC) and outward-facing (OF) states, which we are able to characterize using molecular dynamics (MD) simulations. The structural knowledge of the OC and OF state is important to fully understand the major energy barrier associated with the transport cycle. In order to gain functional insight into the interstate dynamics, we performed extensive all atom MD simulations. The Markov state model was constructed to identify the free energy barriers between the states, and kinetic information on intermediate pathways was obtained using the transition pathway theory (TPT). TPT shows that the OF state is obtained by the movement of TM1 and TM7 at the extracellular side approximately 12-16 Å away from each other, and the inward movement of TM4 and TM10 at the intracellular halves to 3-4 Å characterizes the OC state. Helix distance distributions obtained from MD simulations were compared with experimental double electron-electron resonance spectroscopy and were found to be in excellent agreement with previous studies. We also predicted the optimal positions for placement of methane thiosulfonate spin label probes to capture the slowest protein dynamics. Our finding sheds light on the conformational cycle of this key membrane transporter and the functional relationships between the multiple intermediate states.
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Affiliation(s)
- Balaji Selvam
- Department of Chemical and Biomolecular Engineering, Center for Biophysics and Quantitative
Biology, and Department
of Plant Biology, University of Illinois
at Urbana-Champaign, Urbana, Illinois, United States
| | - Shriyaa Mittal
- Department of Chemical and Biomolecular Engineering, Center for Biophysics and Quantitative
Biology, and Department
of Plant Biology, University of Illinois
at Urbana-Champaign, Urbana, Illinois, United States
| | - Diwakar Shukla
- Department of Chemical and Biomolecular Engineering, Center for Biophysics and Quantitative
Biology, and Department
of Plant Biology, University of Illinois
at Urbana-Champaign, Urbana, Illinois, United States
- E-mail:
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209
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Luchini A, Nzulumike ANO, Lind TK, Nylander T, Barker R, Arleth L, Mortensen K, Cárdenas M. Towards biomimics of cell membranes: Structural effect of phosphatidylinositol triphosphate (PIP 3) on a lipid bilayer. Colloids Surf B Biointerfaces 2018; 173:202-209. [PMID: 30292933 DOI: 10.1016/j.colsurfb.2018.09.031] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 08/31/2018] [Accepted: 09/13/2018] [Indexed: 01/08/2023]
Abstract
Phosphoinositide (PIP) lipids are anionic phospholipids playing a fundamental role for the activity of several transmembrane and soluble proteins. Among all, phosphoinositol-3',4',5'-trisphosphate (PIP3) is a secondary signaling messenger that regulates the function of proteins involved in cell growth and gene transcription. The present study aims to reveal the structure of PIP-containing lipid membranes, which so far has been little explored. For this purpose, supported lipid bilayers (SLBs) containing 1,2-dioleoyl-sn-glycero-3-phospho-(1'-myo-inositol-3',4',5'-trisphosphate (DOPIP3) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) were used as mimics of biomembranes. Surface sensitive techniques, i.e. Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), Atomic Force Microscopy (AFM) and Neutron Reflectometry (NR), provided detailed information on the formation of the SLB and the location of DOPIP3 in the lipid membrane. Specifically, QCM-D and AFM were used to identify the best condition for lipid deposition and to estimate the total bilayer thickness. On the other hand, NR was used to collect experimental structural data on the DOPIP3 location and orientation within the lipid membrane. The two bilayer leaflets showed the same DOPIP3 concentration, thus suggesting the formation of a symmetric bilayer. The headgroup layer thicknesses of the pure POPC and the mixed POPC/DOPIP3 bilayer suggest that the DOPIP3-headgroups have a preferred orientation, which is not perpendicular to the membrane surface, but instead it is close to the surrounding lipid headgroups. These results support the proposed PIP3 tendency to interact with the other lipid headgroups as PC, so far exclusively suggested by MD simulations.
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Affiliation(s)
- Alessandra Luchini
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Achebe N O Nzulumike
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Tania K Lind
- Nano-Science Center and Institute of Chemistry, Copenhagen University, Universitetsparken 5, 2100, Copenhagen, Denmark; Biofilms Research Center for Biointerfaces and Department of Biomedical Science, Faculty of Health and Society, Malmö University, Per Albin Hanssons Väg 35, 214 32, Malmö, Sweden
| | - Tommy Nylander
- Physical Chemistry 1, Lund University, PO Box 124, 221 00, Lund, Sweden
| | - Robert Barker
- Institut Laue-Langevin, 71 Avenue des Martyrs, 38000, Grenoble, France
| | - Lise Arleth
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Kell Mortensen
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen, Denmark
| | - Marité Cárdenas
- Biofilms Research Center for Biointerfaces and Department of Biomedical Science, Faculty of Health and Society, Malmö University, Per Albin Hanssons Väg 35, 214 32, Malmö, Sweden.
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210
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Sajadi F, Rowley CN. Simulations of lipid bilayers using the CHARMM36 force field with the TIP3P-FB and TIP4P-FB water models. PeerJ 2018; 6:e5472. [PMID: 30128211 PMCID: PMC6097494 DOI: 10.7717/peerj.5472] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 07/28/2018] [Indexed: 12/13/2022] Open
Abstract
The CHARMM36 force field for lipids is widely used in simulations of lipid bilayers. The CHARMM family of force fields were developed for use with the mTIP3P water model. This water model has an anomalously high dielectric constant and low viscosity, which limits its accuracy in the calculation of quantities like permeability coefficients. The TIP3P-FB and TIP4P-FB water models are more accurate in terms of the dielectric constant and transport properties, which could allow more accurate simulations of systems containing water and lipids. To test whether the CHARMM36 lipid force field is compatible with the TIP3P-FB and TIP4P-FB water models, we have performed simulations of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine bilayers. The calculated headgroup area, compressibility, order parameters, and X-ray form factors are in good agreement with the experimental values, indicating that these improved water models can be used with the CHARMM36 lipid force field without modification when calculating membrane physical properties. The water permeability predicted by these models is significantly different; the mTIP3P-model diffusion in solution and at the lipid-water interface is anomalously fast due to the spuriously low viscosity of mTIP3P-model water, but the potential of mean force of permeation is higher for the TIP3P-FB and TIP4P-FB models due to their high excess chemical potentials. As a result, the rates of water permeation calculated the FB water models are slower than the experimental value by a factor of 15-17, while simulations with the mTIP3P model only underestimate the water permeability by a factor of 3.
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Affiliation(s)
- Fatima Sajadi
- Department of Chemistry, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Christopher N Rowley
- Department of Chemistry, Memorial University of Newfoundland, St. John's, NL, Canada
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211
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Meker S, Chin H, Sut TN, Cho NJ. Amyloid-β Peptide Triggers Membrane Remodeling in Supported Lipid Bilayers Depending on Their Hydrophobic Thickness. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:9548-9560. [PMID: 30021071 DOI: 10.1021/acs.langmuir.8b01196] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Amyloid-β (Aβ) peptide has been implicated in Alzheimer's disease, which is a leading cause of death worldwide. The interaction of Aβ peptides with the lipid bilayers of neuronal cells is a critical step in disease pathogenesis. Recent evidence indicates that lipid bilayer thickness influences Aβ membrane-associated aggregation, while understanding how Aβ interacts with lipid bilayers remains elusive. To address this question, we employed supported lipid bilayer (SLB) platforms composed of different-length phosphatidylcholine (PC) lipids (C12:0 DLPC, C18:1 DOPC, C18:1-C16:0 POPC), and characterized the resulting interactions with soluble Aβ monomers. Quartz crystal microbalance-dissipation (QCM-D) experiments identified concentration-dependent Aβ peptide adsorption onto all tested SLBs, which was corroborated by fluorescence recovery after photobleaching (FRAP) experiments indicating that higher Aβ concentrations led to decreased membrane fluidity. These commonalities pointed to strong Aβ peptide-membrane interactions in all cases. Notably, time-lapsed fluorescence microscopy revealed major differences in Aβ-induced membrane morphological responses depending on SLB hydrophobic thickness. For thicker DOPC and POPC SLBs, membrane remodeling involved the formation of elongated tubule and globular structures as a passive means to regulate membrane stress depending on Aβ concentration. In marked contrast, thin DLPC SLBs were not able to accommodate extensive membrane remodeling. Taken together, our findings reveal that membrane thickness influences the membrane morphological response triggered upon Aβ adsorption.
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Affiliation(s)
- Sigalit Meker
- School of Materials Science and Engineering , Nanyang Technological University , 639798 , Singapore
- Centre for Biomimetic Sensor Science , Nanyang Technological University , 637553 , Singapore
| | - Hokyun Chin
- School of Materials Science and Engineering , Nanyang Technological University , 639798 , Singapore
- Centre for Biomimetic Sensor Science , Nanyang Technological University , 637553 , Singapore
| | - Tun Naw Sut
- School of Materials Science and Engineering , Nanyang Technological University , 639798 , Singapore
- Centre for Biomimetic Sensor Science , Nanyang Technological University , 637553 , Singapore
| | - Nam-Joon Cho
- School of Materials Science and Engineering , Nanyang Technological University , 639798 , Singapore
- Centre for Biomimetic Sensor Science , Nanyang Technological University , 637553 , Singapore
- School of Chemical and Biomedical Engineering , Nanyang Technological University , 637459 , Singapore
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212
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Khakbaz P, Klauda JB. Investigation of phase transitions of saturated phosphocholine lipid bilayers via molecular dynamics simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1489-1501. [DOI: 10.1016/j.bbamem.2018.04.014] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 04/26/2018] [Accepted: 04/26/2018] [Indexed: 12/01/2022]
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213
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Peralta MF, Smith H, Moody D, Tristram-Nagle S, Carrer DC. Effect of Anti-Leishmania Drugs on the Structural and Elastic Properties of Ultradeformable Lipid Membranes. J Phys Chem B 2018; 122:7332-7339. [PMID: 29972641 DOI: 10.1021/acs.jpcb.8b04001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Drugs for treating Leishmaniasis, a parasitic tropical orphan disease, currently have several limitations on their use, which topical treatments could alleviate. Topical treatment requires penetration of drugs deep into the skin, which is aided by encapsulation within ultradeformable liposomes. Penetrability depends on the flexibility of the lipid membrane, which may be affected by the drugs. We have studied the biophysical effects of four anti-Leishmania drugs (miltefosine (Milt), amphotericin B (AmpB), indole (Ind), and imiquimod (Imiq)) on a soy phosphatidylcholine/sodium cholate membrane. Using diffuse X-ray scattering techniques, we determined bending modulus ( KC) and chain order parameter ( SX-ray) of the membrane at several drug concentrations. Form factor scattering data allowed construction of electron density profiles, which yielded bilayer thickness and area per lipid. Results show that AmpB had the largest effect on KC and SX-ray, causing the bilayer to lose integrity at high concentrations. Imiq and Ind induced slight membrane stiffening, whereas Milt had little effect. Imiq also notably decreased chain order at high concentrations. These results will aid in the design of new topical treatments, where Milt, Ind, and Imiq could be used at any concentration without affecting liposome integrity or physical properties, whereas AmpB should not be used at high concentrations.
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Affiliation(s)
- Ma Florencia Peralta
- Instituto de Investigación Médica M. y M. Ferreyra-INIMEC , CONICET-Universidad Nacional de Córdoba , Córdoba 5000 , Argentina
| | - Hannah Smith
- Biological Physics Group, Physics Department , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Diamond Moody
- Biological Physics Group, Physics Department , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Stephanie Tristram-Nagle
- Biological Physics Group, Physics Department , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States
| | - Dolores C Carrer
- Instituto de Investigación Médica M. y M. Ferreyra-INIMEC , CONICET-Universidad Nacional de Córdoba , Córdoba 5000 , Argentina
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214
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Clustering and separation of hydrophobic nanoparticles in lipid bilayer explained by membrane mechanics. Sci Rep 2018; 8:10810. [PMID: 30018296 PMCID: PMC6050295 DOI: 10.1038/s41598-018-28965-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 07/03/2018] [Indexed: 01/05/2023] Open
Abstract
Small hydrophobic gold nanoparticles with diameter lower than the membrane thickness can form clusters or uniformly distribute within the hydrophobic core of the bilayer. The coexistence of two stable phases (clustered and dispersed) indicates the energy barrier between nanoparticles. We calculated the distance dependence of the membrane-mediated interaction between two adjacent nanoparticles. In our model we consider two deformation modes: the monolayer bending and the hydroxycarbon chain stretching. Existence of an energy barrier between the clustered and the separated state of nanoparticles was predicted. Variation analysis of the membrane mechanical parameters revealed that the energy barrier between two membrane embedded nanoparticles is mainly the consequence of the bending deformation and not change of the thickness of the bilayer in the vicinity of nanoparticles. It is shown, that the forces between the nanoparticles embedded in the biological membrane could be either attractive or repulsive, depending on the mutual distance between them.
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215
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Cardelli C, Barducci A, Procacci P. Lipid tempering simulation of model biological membranes on parallel platforms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1480-1488. [DOI: 10.1016/j.bbamem.2018.04.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/10/2018] [Accepted: 04/25/2018] [Indexed: 11/17/2022]
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216
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Salih R, Matthai CC. Computer simulations of the diffusion of Na + and Cl - ions across POPC lipid bilayer membranes. J Chem Phys 2018; 146:105101. [PMID: 28298128 DOI: 10.1063/1.4977703] [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
We have carried out molecular dynamics simulations using NAMD to study the diffusivity of Na and Cl ions across a POPC lipid bilayer membrane. We show that an imbalance of positively and negatively charged ions on either side of the membrane leads to the diffusion of ions and water molecules. We considered the cases of both weak and very strong charge imbalance across the membrane. The diffusion coefficients of the ions have been determined from the mean square displacements of the particles as a function of time. We find that for strong electrochemical gradients, both the Na and Cl ions diffuse rapidly through pores in the membrane with diffusion coefficients up to ten times larger than in water. Rather surprisingly, we found that although the Na ions are the first to begin the permeation process due to the lower potential barrier that they experience compared to the Cl ions, the latter complete the permeation across the barrier more quickly due to their faster diffusion rates.
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Affiliation(s)
- Rangeen Salih
- Department of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom
| | - C C Matthai
- Department of Physics and Astronomy, Cardiff University, Cardiff, United Kingdom
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217
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Mukherjee P, Madarati H, Ridgway ND, Atkinson J. Lipid and membrane recognition by the oxysterol binding protein and its phosphomimetic mutant using dual polarization interferometry. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:2356-2365. [PMID: 29879417 DOI: 10.1016/j.bbamem.2018.05.022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2018] [Revised: 05/22/2018] [Accepted: 05/31/2018] [Indexed: 10/14/2022]
Abstract
OSBP binds, extracts and transfers sterols and phosphatidylinositol-4-phosphate (PI(4)P between liposomes, but the sequence of steps at the membrane surface leading to ligand removal is poorly characterized. In this study, we used dual polarization interferometry (DPI), a label-free surface analytical technique, to characterize the interaction of recombinant, purified OSBP as it flows over immobilized dioleoyl-phosphatidylcholine (DOPC) bilayers containing PI(4)P, cholesterol or 25-hydroxycholesterol. Kinetics of membrane interaction were analyzed for PI(4)P-binding and phosphorylation mutants of OSBP. Wild-type OSBP demonstrated a distinctive association with immobilized DOPC bilayers containing 1-8 mol% PI(4)P that was characterized by initial saturable binding followed by desorption, indicative of PI(4)P extraction. In support of this conclusion, an OSBP mutant with impaired binding and extraction of PI(4)P was stably absorbed to PI(4)P-containing membranes, while a pleckstrin homology domain mutant did not associate with PI(4)P-containing membranes. The inclusion of >2 mol% cholesterol, but not 25-hydroxycholesterol, in membranes, enhanced the absorption of the wild-type OSBP. A phosphomimetic of OSBP with enhanced in vitro sterol binding activity displayed membrane interaction properties similar to wild-type. These real-time flow studies allow us to dissect the association of OSBP with PI(4)P into discrete components; initial recruitment to PI(4)P membranes by the PH domain, detection and extraction of PI(4)P, and desorption due to ligand depletion.
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Affiliation(s)
- Parthajit Mukherjee
- Department of Chemistry and Centre for Biotechnology, Brock University, St. Catharines, Ontario L2A 3S1, Canada
| | - Hasam Madarati
- Department of Chemistry and Centre for Biotechnology, Brock University, St. Catharines, Ontario L2A 3S1, Canada
| | - Neale D Ridgway
- Department of Pediatrics and Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada
| | - Jeffrey Atkinson
- Department of Chemistry and Centre for Biotechnology, Brock University, St. Catharines, Ontario L2A 3S1, Canada.
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218
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Gupta S, De Mel JU, Perera RM, Zolnierczuk P, Bleuel M, Faraone A, Schneider GJ. Dynamics of Phospholipid Membranes beyond Thermal Undulations. J Phys Chem Lett 2018; 9:2956-2960. [PMID: 29754484 DOI: 10.1021/acs.jpclett.8b01008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We investigated the molecular dynamics of unilamellar liposomes by neutron spin echo spectroscopy. We report the first experimental evidence of a short-range motion at the length scale of the size of the headgroup of a lipid. The associated mean squared displacement shows a t0.26 dependence in the pico- to nanosecond region that indicates another process beyond the predictions of the Zilman-Granek (ZG) model ( t0.66) and translational diffusion ( t1). A comparison with theory shows that the observed low exponent is associated with a non-Gaussian transient trapping of lipid molecules in a local area and supports the continuous time random walk model. The analysis of the mean squared displacement leads to the important conclusion that the friction at the interface between water and liposomes plays a minor role. Center of mass diffusion of liposomes and transient trapping of lipids define the range in which the ZG model can be applied to analyze membrane fluctuations.
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Affiliation(s)
- Sudipta Gupta
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Judith U De Mel
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Rasangi M Perera
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
| | - Piotr Zolnierczuk
- Jülich Centre for Neutron Science (JCNS), Outstation at SNS, POB 2008, 1 Bethel Valley Road , Oak Ridge , Tennessee 37831 , United States
| | - Markus Bleuel
- NIST Center for Neutron Research , National Institute of Standards and Technology , Gaithersburg , Maryland 20899-6100 , United States
| | - Antonio Faraone
- NIST Center for Neutron Research , National Institute of Standards and Technology , Gaithersburg , Maryland 20899-6100 , United States
| | - Gerald J Schneider
- Department of Chemistry , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
- Department of Physics & Astronomy , Louisiana State University , Baton Rouge , Louisiana 70803 , United States
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219
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Gironi B, Paolantoni M, Morresi A, Foggi P, Sassi P. Influence of Dimethyl Sulfoxide on the Low-Temperature Behavior of Cholesterol-Loaded Palmitoyl-oleyl-phosphatidylcholine Membranes. J Phys Chem B 2018; 122:6396-6402. [DOI: 10.1021/acs.jpcb.8b02333] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Beatrice Gironi
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
| | - Marco Paolantoni
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
| | - Assunta Morresi
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
| | - Paolo Foggi
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
- European Laboratory for Non Linear Spectroscopy (LENS), Università di Firenze, via Nello Carrara 1, 50019 Sesto Fiorentino, Florence, Italy
- CNR-INO, Via Nello Carrara 1, 50019 Sesto Fiorentino, Florence, Italy
- CNR-ICCOM, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Florence, Italy
| | - Paola Sassi
- Dipartimento di Chimica, Biologia e Biotecnologie, Università di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
- Centro di Eccellenza sui Materiali Innovativi Nanostrutturati (CEMIN), Università di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
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220
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Tse CH, Comer J, Wang Y, Chipot C. Link between Membrane Composition and Permeability to Drugs. J Chem Theory Comput 2018; 14:2895-2909. [PMID: 29771515 DOI: 10.1021/acs.jctc.8b00272] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Prediction of membrane permeability to small molecules represents an important aspect of drug discovery. First-principles calculations of this quantity require an accurate description of both the thermodynamics and kinetics that underlie translocation of the permeant across the lipid bilayer. In this contribution, the membrane permeability to three drugs, or drug-like molecules, namely, 9-anthroic acid (ANA), 2',3'-dideoxyadenosine (DDA), and hydrocortisone (HYL), are estimated in a pure 1-palmitoyl-2-oleoylphosphatidylcholine (POPC) and in a POPC:cholesterol (2:1) mixture. On the basis of independent 2-5-μs free-energy calculations combined with a time-fractional Smoluchowski determination of the diffusivity, the estimated membrane permeabilities to these chemically diverse permeants fall within an order of magnitude from the experimental values obtained in egg-lecithin bilayers, with the exception of HYL in pure POPC. This exception is particularly interesting because the calculated permeability of the sterol-rich bilayer to HYL, in close agreement with the experimental value, is about 600 times lower than that of the pure POPC bilayer to HYL. In contrast, the permeabilities to ANA and DDA differ by less than a factor of 10 between the pure POPC and POPC:cholesterol bilayers. The unusual behavior of HYL, a large, amphiphilic compound, may be linked with the longer range perturbation of the lipid bilayer it induces, compared to ANA and DDA, suggestive of a possibly different translocation mechanism. We find that the tendency of lower permeabilities of the POPC:cholesterol bilayer relative to those of the pure POPC one is a consequence of increased free-energy barriers. Beyond reporting accurate estimates of the membrane permeability, the present contribution also demonstrates that rigorous free-energy calculations and a fractional-diffusion model are key in revealing the molecular phenomena linking the composition of a membrane to its permeability to drugs.
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Affiliation(s)
- Chi Hang Tse
- Shenzhen Research Institute , The Chinese University of Hong Kong , Shatin , Hong Kong SAR , China.,Department of Physics , The Chinese University of Hong Kong , Shatin , Hong Kong SAR , China
| | - Jeffrey Comer
- Institute of Computational Comparative Medicine and Nanotechnology Innovation Center of Kansas State, Department of Anatomy and Physiology , Kansas State University , Manhattan , Kansas 66506 , United States
| | - Yi Wang
- Shenzhen Research Institute , The Chinese University of Hong Kong , Shatin , Hong Kong SAR , China.,Department of Physics , The Chinese University of Hong Kong , Shatin , Hong Kong SAR , China
| | - Christophe Chipot
- Laboratoire International Associé Centre, National de la Recherche Scientifique et University of Illinois at Urbana-Champaign, Unité Mixte de Recherche No. 7019 , Université de Lorraine , B.P. 70239, 54506 Vandœuvre-lès-Nancy cedex , France.,Theoretical and Computational Biophysics Group, Beckman Institute for Advanced Science and Technology , University of Illinois at Urbana-Champaign , 405 North Mathews Avenue , Urbana , Illinois 61801 , United States.,Department of Physics , University of Illinois at Urbana-Champaign , 1110 West Green Street , Urbana , Illinois 61801 , United States
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221
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Beltramo PJ, Scheidegger L, Vermant J. Toward Realistic Large-Area Cell Membrane Mimics: Excluding Oil, Controlling Composition, and Including Ion Channels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:5880-5888. [PMID: 29715042 DOI: 10.1021/acs.langmuir.8b00837] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Capacitance measurements provide unique insights into the thickness, compressibility, and composition of large-area membrane bilayers and are used here in addition to demonstrate the successful incorporation of model ion channels. The simultaneous ability to control the bilayer size, manipulate tension, and optically monitor and electrically stimulate freestanding membranes enables precise determination of their specific capacitance and thickness across a wide range of areas. We confirm that membranes formed by this recently developed technique have capacitive properties similar to those formed by existing protocols, including solvent-free approaches, and discuss the effect using either hexadecane or squalene as the oil solvent. The results obtained here are relevant for other methods where lipid membranes are reconstituted from a bulk oil solvent. Because biological membranes have a diverse phospholipid profile, we show that the technique can successfully reconstitute membranes with binary composition mixtures. As an outlook, we show the capability of model membrane proteins, specifically α-hemolysin and alamethicin, to be incorporated into the formed bilayers and measure ion transport.
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Affiliation(s)
- Peter J Beltramo
- Department of Chemical Engineering , University of Massachusetts Amherst , Amherst , Massachusetts 01003 , United States
| | - Laura Scheidegger
- Department of Materials , ETH Zürich , Vladimir-Prelog-Weg 5 , 8093 Zürich , Switzerland
| | - Jan Vermant
- Department of Materials , ETH Zürich , Vladimir-Prelog-Weg 5 , 8093 Zürich , Switzerland
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222
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Bolognesi G, Friddin MS, Salehi-Reyhani A, Barlow NE, Brooks NJ, Ces O, Elani Y. Sculpting and fusing biomimetic vesicle networks using optical tweezers. Nat Commun 2018; 9:1882. [PMID: 29760422 PMCID: PMC5951844 DOI: 10.1038/s41467-018-04282-w] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 04/10/2018] [Indexed: 11/16/2022] Open
Abstract
Constructing higher-order vesicle assemblies has discipline-spanning potential from responsive soft-matter materials to artificial cell networks in synthetic biology. This potential is ultimately derived from the ability to compartmentalise and order chemical species in space. To unlock such applications, spatial organisation of vesicles in relation to one another must be controlled, and techniques to deliver cargo to compartments developed. Herein, we use optical tweezers to assemble, reconfigure and dismantle networks of cell-sized vesicles that, in different experimental scenarios, we engineer to exhibit several interesting properties. Vesicles are connected through double-bilayer junctions formed via electrostatically controlled adhesion. Chemically distinct vesicles are linked across length scales, from several nanometres to hundreds of micrometres, by axon-like tethers. In the former regime, patterning membranes with proteins and nanoparticles facilitates material exchange between compartments and enables laser-triggered vesicle merging. This allows us to mix and dilute content, and to initiate protein expression by delivering biomolecular reaction components. Assembly of higher-order artificial vesicles can unlock new applications. Here, the authors use optical tweezers to construct user-defined 2D and 3D architectures of chemically distinct vesicles and demonstrate inter-vesicle communication and light-enabled compartment merging.
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Affiliation(s)
- Guido Bolognesi
- Department of Chemical Engineering, Loughborough University, Loughborough, LE11 3TU, UK
| | - Mark S Friddin
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Ali Salehi-Reyhani
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.,Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.,FABRICELL, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Nathan E Barlow
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.,Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Oscar Ces
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. .,Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. .,FABRICELL, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.
| | - Yuval Elani
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. .,Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. .,FABRICELL, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.
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223
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Percebom AM, Ferreira GA, Catini DR, Bernardes JS, Loh W. Phase Behavior Controlled by the Addition of Long-Chain n-Alcohols in Systems of Cationic Surfactant/Anionic Polyion Complex Salts and Water. J Phys Chem B 2018; 122:4861-4869. [PMID: 29668285 DOI: 10.1021/acs.jpcb.8b01788] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Phase behavior of surfactants in water may be affected by the addition of a third component, and the present study discusses how long-chain n-alcohols affect phase transitions of systems formed by the surfactant hexadecyltrimethylammonium bromide, C16TAB, or its complex salts formed with polyacrylate, C16TAPA30, as well as other previously reported complex salts/water/alcohol systems. Structural characterization by X-ray diffraction patterns at small and wide angles and different temperatures was performed for samples containing n-decanol, n-dodecanol, or n-tetradecanol. Differential scanning calorimetry (DSC) was also used to study the phase transition. The results allowed us to observe and understand the coexistence of lamellar gel (Lβ) and lamellar liquid-crystal (Lα) phases, elucidating the structure of a previously reported mesophase, proposing an alternative assignment. Whereas the chain-melting transition is well-known to be sharp for lipids, we have found that it is broader for C16TAB and C16TAPA in the presence of these n-alcohols. We have investigated the effects of their composition and chain length on the temperature and enthalpy of transition. This elucidates why the addition of n-alcohols with chains slightly shorter than that of the surfactants leads to the formation of an ordered gel-like lamellar phase (Lβ). n-Alcohols act as neutral cosurfactants, leading to more packing, and all of the factors converge to a limit situation, associated with a common critical area occupied by each alkyl chain. We compared our results with other mesophase systems from the literature, demonstrating that the same trends of phase behavior occur for complex salts of other polyelectrolytes with alkyltrimethylammonium surfactants.
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Affiliation(s)
- Ana M Percebom
- Institute of Chemistry , University of Campinas (UNICAMP) , PO Box 6154, 13084-970 Campinas , São Paulo , Brazil.,Department of Chemistry , Pontifical Catholic University of Rio de Janeiro , 22451-900 Rio de Janeiro , Rio de Janeiro , Brazil
| | - Guilherme A Ferreira
- Institute of Chemistry , University of Campinas (UNICAMP) , PO Box 6154, 13084-970 Campinas , São Paulo , Brazil
| | - Daniel Rege Catini
- Institute of Chemistry , University of Campinas (UNICAMP) , PO Box 6154, 13084-970 Campinas , São Paulo , Brazil
| | - Juliana S Bernardes
- Institute of Chemistry , University of Campinas (UNICAMP) , PO Box 6154, 13084-970 Campinas , São Paulo , Brazil.,Brazilian Nanotechnology National Laboratory (LNNano), Brazilian Center for Research in Energy and Materials (CNPEM) , 13083-970 Campinas , São Paulo , Brazil
| | - Watson Loh
- Institute of Chemistry , University of Campinas (UNICAMP) , PO Box 6154, 13084-970 Campinas , São Paulo , Brazil
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224
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Effect of 5-trans Isomer of Arachidonic Acid on Model Liposomal Membranes Studied by a Combined Simulation and Experimental Approach. J Membr Biol 2018; 251:475-489. [PMID: 29610947 DOI: 10.1007/s00232-018-0029-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Accepted: 03/08/2018] [Indexed: 02/07/2023]
Abstract
Unsaturated fatty acids are found in humans predominantly in the cis configuration. Fatty acids in the trans configuration are primarily the result of human processing (trans fats), but can also be formed endogenously by radical stress. The cis-trans isomerization of fatty acids by free radicals could be connected to several pathologies. Trans fats have been linked to an increased risk of coronary artery disease; however, the reasons for the resulting pathogenesis remain unclear. Here, we investigate the effect of a mono-trans isomer of arachidonic acid (C20:4-5trans, 8cis, 11cis, 14cis) produced by free radicals in physiological concentration on a model erythrocyte membrane using a combined experimental and theoretical approach. Molecular Dynamics (MD) simulations of two model lipid bilayers containing arachidonic acid and its 5-trans isomer in 3 mol% were carried out for this purpose. The 5-trans isomer formation in the phospholipids was catalyzed by HOCH2CH2S· radicals, generated from the corresponding thiol by γ-irradiation, in multilamellar vesicles of SAPC. Large unilamellar vesicles were made by the extrusion method (LUVET) as a biomimetic model for cis-trans isomerization. Atomic Force Microscopy and Dynamic Light Scattering were used to measure the average size, morphology, and the z-potential of the liposomes. Both results from MD simulations and experiments are in agreement and indicate that the two model membranes display different physicochemical properties in that the bilayers containing the trans fatty acids were more ordered and more rigid than those containing solely the cis arachidonic acid. Correspondingly, the average size of the liposomes containing trans isomers was smaller than the ones without.
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225
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Jaschonek S, Cascella M, Gauss J, Diezemann G, Milano G. Intramolecular structural parameters are key modulators of the gel-liquid transition in coarse grained simulations of DPPC and DOPC lipid bilayers. Biochem Biophys Res Commun 2018; 498:327-333. [PMID: 29101041 DOI: 10.1016/j.bbrc.2017.10.132] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/29/2017] [Accepted: 10/23/2017] [Indexed: 12/11/2022]
Abstract
The capability of coarse-grained models based on the MARTINI mapping to reproduce the gel-liquid phase transition in saturated and unsaturated model lipids was investigated. We found that the model is able to reproduce a lower critical temperature for 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) with respect to 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). Nonetheless, the appearance of a gel phase for DOPC is strictly dependent on the intramolecular parameters chosen to model its molecular structure. In particular, we show that the bending angle at the coarse-grained bead corresponding to the unsaturated carbon-carbon bond acts as an order parameter determining the temperature of the phase transition. Structural analysis of the molecular dynamics simulations runs evidences that in the gel phase, the packing of the lipophilic tails of DOPC assume a different conformation than in the liquid phase. In the latter phase, the DOPC geometry resembles that of the relaxed free molecule. DPPC:DOPC mixtures show a single phase transition temperature, indicating that the observation of a phase separation between the two lipids requires the simulation of systems with sizes much larger than the ones used here.
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Affiliation(s)
- Stefan Jaschonek
- Institut für Physikalische Chemie, Universität Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany.
| | - Michele Cascella
- Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, Postboks 1033 Blindern, N-0315 Oslo, Norway.
| | - Jürgen Gauss
- Institut für Physikalische Chemie, Universität Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany.
| | - Gregor Diezemann
- Institut für Physikalische Chemie, Universität Mainz, Duesbergweg 10-14, D-55128 Mainz, Germany.
| | - Giuseppe Milano
- Dipartimento di Chimica e Biologia, Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano, Italy.
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226
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Lyu Y, Xiang N, Mondal J, Zhu X, Narsimhan G. Characterization of Interactions between Curcumin and Different Types of Lipid Bilayers by Molecular Dynamics Simulation. J Phys Chem B 2018; 122:2341-2354. [PMID: 29394060 DOI: 10.1021/acs.jpcb.7b10566] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Yuan Lyu
- Department of Agricultural
and Biological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Ning Xiang
- Department of Agricultural
and Biological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jagannath Mondal
- Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, 36/P, Gopanapally Village, Serilingampally Mandal, Ranga Reddy District, Hyderabad 500107, India
| | - Xiao Zhu
- Research
Computing, Rosen Center for Advanced Computing, Purdue University, West Lafayette, Indiana 47907, United States
| | - Ganesan Narsimhan
- Department of Agricultural
and Biological Engineering, Purdue University, West Lafayette, Indiana 47907, United States
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227
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Liu YC, Lee IC, Lei KF. Toward the Development of an Artificial Brain on a Micropatterned and Material-Regulated Biochip by Guiding and Promoting the Differentiation and Neurite Outgrowth of Neural Stem/Progenitor Cells. ACS APPLIED MATERIALS & INTERFACES 2018; 10:5269-5277. [PMID: 29400947 DOI: 10.1021/acsami.7b17863] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
An in vitro model mimicking the in vivo environment of the brain must be developed to study neural communication and regeneration and to obtain an understanding of cellular and molecular responses. In this work, a multilayered neural network was successfully constructed on a biochip by guiding and promoting neural stem/progenitor cell differentiation and network formation. The biochip consisted of 3 × 3 arrays of cultured wells connected with channels. Neurospheroids were cultured on polyelectrolyte multilayer (PEM) films in the culture wells. Neurite outgrowth and neural differentiation were guided and promoted by the micropatterns and the PEM films. After 5 days in culture, a 3 × 3 neural network was constructed on the biochip. The function and the connections of the network were evaluated by immunocytochemistry and impedance measurements. Neurons were generated and produced functional and recyclable synaptic vesicles. Moreover, the electrical connections of the neural network were confirmed by measuring the impedance across the neurospheroids. The current work facilitates the development of an artificial brain on a chip for investigations of electrical stimulations and recordings of multilayered neural communication and regeneration.
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Affiliation(s)
- Yung-Chiang Liu
- Ph.D. Program in Biomedical Engineering, College of Engineering, ‡Graduate Institute of Biochemical and Biomedical Engineering, ∥Graduate Institute of Medical Mechatronics, and ⊥Department of Mechanical Engineering, Chang Gung University , Taoyuan 333, Taiwan
- Neurosurgery Department and #Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou , Taoyuan 333, Taiwan
| | - I-Chi Lee
- Ph.D. Program in Biomedical Engineering, College of Engineering, ‡Graduate Institute of Biochemical and Biomedical Engineering, ∥Graduate Institute of Medical Mechatronics, and ⊥Department of Mechanical Engineering, Chang Gung University , Taoyuan 333, Taiwan
- Neurosurgery Department and #Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou , Taoyuan 333, Taiwan
| | - Kin Fong Lei
- Ph.D. Program in Biomedical Engineering, College of Engineering, ‡Graduate Institute of Biochemical and Biomedical Engineering, ∥Graduate Institute of Medical Mechatronics, and ⊥Department of Mechanical Engineering, Chang Gung University , Taoyuan 333, Taiwan
- Neurosurgery Department and #Department of Radiation Oncology, Chang Gung Memorial Hospital, Linkou , Taoyuan 333, Taiwan
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228
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Doktorova M, Harries D, Khelashvili G. Determination of bending rigidity and tilt modulus of lipid membranes from real-space fluctuation analysis of molecular dynamics simulations. Phys Chem Chem Phys 2018. [PMID: 28627570 DOI: 10.1039/c7cp01921a] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
We have recently developed a novel computational methodology (termed RSF for Real-Space Fluctuations) to quantify the bending rigidity and tilt modulus of lipid membranes from real-space analysis of fluctuations in the tilt and splay degrees of freedom as sampled in molecular dynamics (MD) simulations. In this article, we present a comprehensive study that combines results from the application of the RSF method to a wide range of lipid bilayer systems that encompass membranes of different fluidities and sizes, including lipids with saturated and unsaturated lipid tails, single and multi-component lipid systems, as well as non-standard lipids such as the four-tailed cardiolipin. By comparing the material properties calculated with the RSF method to those obtained from experimental data and from other computational methodologies, we rigorously demonstrate the validity of our approach and show its robustness. This should allow for future applications of even more complex lipidic assemblies, whose material properties are not tractable by other computational techniques. In addition, we discuss the relationship between different definitions of the tilt modulus appearing in current literature to address some important unresolved discrepancies in the field.
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Affiliation(s)
- M Doktorova
- Tri-Institutional PhD Program in Computational Biology and Medicine, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA
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229
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Lee TH, Sani MA, Overall S, Separovic F, Aguilar MI. Effect of phosphatidylcholine bilayer thickness and molecular order on the binding of the antimicrobial peptide maculatin 1.1. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:300-309. [DOI: 10.1016/j.bbamem.2017.10.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 09/18/2017] [Accepted: 10/08/2017] [Indexed: 01/01/2023]
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230
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Mandala VS, Gelenter MD, Hong M. Transport-Relevant Protein Conformational Dynamics and Water Dynamics on Multiple Time Scales in an Archetypal Proton Channel: Insights from Solid-State NMR. J Am Chem Soc 2018; 140:1514-1524. [PMID: 29303574 DOI: 10.1021/jacs.7b12464] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The influenza M2 protein forms a tetrameric proton channel that conducts protons from the acidic endosome into the virion by shuttling protons between water and a transmembrane histidine. Previous NMR studies have shown that this histidine protonates and deprotonates on the microsecond time scale. However, M2's proton conduction rate is 10-1000 s-1, more than 2 orders of magnitude slower than the histidine-water proton-exchange rate. M2 is also known to be conformationally plastic. To address the disparity between the functional time scale and the time scales of protein conformational dynamics and water dynamics, we have now investigated a W41F mutant of the M2 transmembrane domain using solid-state NMR. 13C chemical shifts of the membrane-bound peptide indicate the presence of two distinct tetramer conformations, whose concentrations depend exclusively on pH and hence the charge-state distribution of the tetramers. High-temperature 2D correlation spectra indicate that these two conformations interconvert at a rate of ∼400 s-1 when the +2 and +3 charge states dominate, which gives the first experimental evidence of protein conformational motion on the transport time scale. Protein 13C-detected water 1H T2 relaxation measurements show that channel water relaxes an order of magnitude faster than bulk water and membrane-associated water, indicating that channel water undergoes nanosecond motion in a pH-independent fashion. These results connect motions on three time scales to explain M2's proton-conduction mechanism: picosecond-to-nanosecond motions of water molecules facilitate proton Grotthuss hopping, microsecond motions of the histidine side chain allow water-histidine proton transfer, while millisecond motions of the entire four-helix bundle constitute the rate-limiting step, dictating the number of protons released into the virion.
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Affiliation(s)
- Venkata S Mandala
- Department of Chemistry, Massachusetts Institute of Technology , 170 Albany Street, Cambridge, Massachusetts 02139, United States
| | - Martin D Gelenter
- Department of Chemistry, Massachusetts Institute of Technology , 170 Albany Street, Cambridge, Massachusetts 02139, United States
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology , 170 Albany Street, Cambridge, Massachusetts 02139, United States
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231
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Adam C, Peters AD, Lizio MG, Whitehead GFS, Diemer V, Cooper JA, Cockroft SL, Clayden J, Webb SJ. The Role of Terminal Functionality in the Membrane and Antibacterial Activity of Peptaibol-Mimetic Aib Foldamers. Chemistry 2018; 24:2249-2256. [PMID: 29210477 DOI: 10.1002/chem.201705299] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Indexed: 01/04/2023]
Abstract
Peptaibols are peptide antibiotics that typically feature an N-terminal acetyl cap, a C-terminal aminoalcohol, and a high proportion of α-aminoisobutyric acid (Aib) residues. To establish how each feature might affect the membrane-activity of peptaibols, biomimetic Aib foldamers with different lengths and terminal groups were synthesised. Vesicle assays showed that long foldamers (eleven Aib residues) with hydrophobic termini had the highest ionophoric activity. C-terminal acids or primary amides inhibited activity, while replacement of an N-terminal acetyl with an azide group made little difference. Crystallography showed that N3 Aib11 CH2 OTIPS folded into a 310 helix 2.91 nm long, which is close to the bilayer hydrophobic width. Planar bilayer conductance assays showed discrete ion channels only for N-acetylated foldamers. However long foldamers with hydrophobic termini had the highest antibacterial activity, indicating that ionophoric activity in vesicles was a better indicator of antibacterial activity than the observation of discrete ion channels.
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Affiliation(s)
- Catherine Adam
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
| | - Anna D Peters
- School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.,Manchester Institute of Biotechnology, University of Manchester, 131 Princess St, Manchester, M1 7DN, UK
| | - M Giovanna Lizio
- School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.,Manchester Institute of Biotechnology, University of Manchester, 131 Princess St, Manchester, M1 7DN, UK
| | - George F S Whitehead
- School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK
| | - Vincent Diemer
- School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.,Manchester Institute of Biotechnology, University of Manchester, 131 Princess St, Manchester, M1 7DN, UK
| | - James A Cooper
- EaStCHEM School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, UK
| | - Scott L Cockroft
- EaStCHEM School of Chemistry, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ, UK
| | - Jonathan Clayden
- School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK
| | - Simon J Webb
- School of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, UK.,Manchester Institute of Biotechnology, University of Manchester, 131 Princess St, Manchester, M1 7DN, UK
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232
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Izquierdo C, Gómez-Tamayo JC, Nebel JC, Pardo L, Gonzalez A. Identifying human diamine sensors for death related putrescine and cadaverine molecules. PLoS Comput Biol 2018; 14:e1005945. [PMID: 29324768 PMCID: PMC5783396 DOI: 10.1371/journal.pcbi.1005945] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 01/24/2018] [Accepted: 12/28/2017] [Indexed: 12/21/2022] Open
Abstract
Pungent chemical compounds originating from decaying tissue are strong drivers of animal behavior. Two of the best-characterized death smell components are putrescine (PUT) and cadaverine (CAD), foul-smelling molecules produced by decarboxylation of amino acids during decomposition. These volatile polyamines act as ‘necromones’, triggering avoidance or attractive responses, which are fundamental for the survival of a wide range of species. The few studies that have attempted to identify the cognate receptors for these molecules have suggested the involvement of the seven-helix trace amine-associated receptors (TAARs), localized in the olfactory epithelium. However, very little is known about the precise chemosensory receptors that sense these compounds in the majority of organisms and the molecular basis of their interactions. In this work, we have used computational strategies to characterize the binding between PUT and CAD with the TAAR6 and TAAR8 human receptors. Sequence analysis, homology modeling, docking and molecular dynamics studies suggest a tandem of negatively charged aspartates in the binding pocket of these receptors which are likely to be involved in the recognition of these small biogenic diamines. The distinctive dead smell comes largely from molecules like cadaverine and putrescine that are produced during decomposition of organic tissues. These volatile compounds act as powerful chemical signals important for the survival of a wide range of species. Previous studies have identified the trace amine-associated receptor 13c (or TAAR13c) in zebrafish as the cognate receptor of cadaverine in bony fishes. In this work, we employed computational strategies to disclose the human TAAR6 and TAAR8 receptors as sensors of the putrescine and cadaverine molecules. Our results indicate that several negatively charged residues in the ligand binding pocket of these receptors constitute the molecular basis for recognition of these necromones in humans.
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Affiliation(s)
- Cristina Izquierdo
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
| | - José C. Gómez-Tamayo
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
| | - Jean-Christophe Nebel
- Faculty of Science, Engineering and Computing, Kingston University, London, United Kingdom
| | - Leonardo Pardo
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
| | - Angel Gonzalez
- Laboratori de Medicina Computacional, Unitat de Bioestadística, Facultat de Medicina, Universitat Autònoma de Barcelona, E-08193 Bellaterra, Spain
- * E-mail:
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233
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Mizuguchi T, Matubayasi N. Free-Energy Analysis of Peptide Binding in Lipid Membrane Using All-Atom Molecular Dynamics Simulation Combined with Theory of Solutions. J Phys Chem B 2018; 122:3219-3229. [DOI: 10.1021/acs.jpcb.7b08241] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Tomoko Mizuguchi
- Institute for Molecular Science, Okazaki, Aichi 444-8585, Japan
- Institute for the Promotion of University Strategy, Kyoto Institute of Technology, Kyoto 606-8585, Japan
| | - Nobuyuki Matubayasi
- Division of Chemical Engineering, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
- Elements Strategy Initiative for Catalysts and Batteries, Kyoto University, Katsura, Kyoto 615-8520, Japan
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234
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Dotson RJ, Pias SC. Reduced Oxygen Permeability upon Protein Incorporation Within Phospholipid Bilayers. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1072:405-411. [PMID: 30178379 DOI: 10.1007/978-3-319-91287-5_65] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Intracellular oxygenation is key to energy metabolism as well as tumor radiation therapy. Although integral proteins are ubiquitous in membranes, few studies have considered their effects on molecular oxygen permeability. Published experimental work with rhodopsin and bacteriorhodopsin has led to the hypothesis that integral proteins lessen membrane oxygen permeability, as well as the permeability of the lipid region. The current work uses atomistic molecular dynamics simulations to test the influence of an ungated potassium channel protein on the oxygen permeability of palmitoyloleoylphosphatidylcholine (POPC) bilayers with and without cholesterol. Consistent with experiment, whole-membrane oxygen permeability is cut in half upon adding 30 wt% potassium channel protein to POPC, and the apparent permeability of the lipid portion of the membrane decreases by 40%. Unexpectedly, oxygen is found to interact directly with the protein surface, accompanied by a 40% reduction of the apparent whole-membrane diffusion coefficient. Similar effects are seen in systems combining the potassium channel with 1:1 POPC/cholesterol, but the magnitude of permeability reduction is smaller by ~30%. Overall, the simulations indicate that integral proteins can reduce oxygen permeability by altering the diffusional path and the local diffusivity. This effect may be especially important in the protein-dense membranes of mitochondria.
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Affiliation(s)
- Rachel J Dotson
- Department of Chemistry, New Mexico Institute of Mining and Technology (New Mexico Tech), Socorro, NM, USA
| | - Sally C Pias
- Department of Chemistry, New Mexico Institute of Mining and Technology (New Mexico Tech), Socorro, NM, USA.
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235
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Williams AT, Donno R, Tirelli N, Dryfe RA. Phospholipid-mediated exfoliation as a facile preparation method for graphene suspensions. RSC Adv 2018; 8:19220-19225. [PMID: 35539657 PMCID: PMC9080625 DOI: 10.1039/c8ra03365j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 05/16/2018] [Indexed: 11/25/2022] Open
Abstract
This paper deals with simple, inexpensive and ‘green’ methods of production for graphene in colloidal dispersion. Herein, we report on such a method by preparing aqueous graphene dispersions via ultrasonic exfoliation in the presence of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). The product predominantly consists of few-layer graphene flakes coated by DOPC with a lateral size of a few tens to hundreds of nm, as confirmed by Raman and X-ray photoelectron spectroscopies, thermogravimetric analysis (TGA), dynamic light scattering (DLS) and atomic force microscopy (AFM). The novelty of this method lies in its dependence on a typical soft matter property: the fluidity of the hydrophobic chains. Stiffer phospholipids such as 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC, which possesses two palmitoyl chains) or 2-oleoyl-1-palmitoyl-sn-glycero-3-phosphocholine (POPC, one palmitoyl, one oleyl chain) are ineffective at dispersing graphene; however, in the presence of cholesterol these phospholipids also become effective mediators. The phospholipid coating renders the flakes compatible with biological environments. A simple, inexpensive and ‘green’ method of production for graphene in colloidal dispersion.![]()
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Affiliation(s)
| | - Roberto Donno
- Laboratory of Polymers and Biomaterials
- Fondazione Istituto Italiano di Tecnologia
- Genoa
- Italy
| | - Nicola Tirelli
- Laboratory of Polymers and Biomaterials
- Fondazione Istituto Italiano di Tecnologia
- Genoa
- Italy
- NorthWest Centre for Advanced Drug Delivery
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236
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Pattnaik GP, Meher G, Chakraborty H. Exploring the Mechanism of Viral Peptide-Induced Membrane Fusion. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1112:69-78. [PMID: 30637691 DOI: 10.1007/978-981-13-3065-0_6] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Membrane fusion is essential in several cellular processes in the existence of eukaryotic cells such as cellular trafficking, compartmentalization, intercellular communication, sexual reproduction, cell division, and endo- and exocytosis. Membrane fusion proceeds in model membranes as well as biological membranes through the rearrangement of lipids. The stalk hypothesis provides a picture of the general nature of lipid rearrangement based on mechanical properties and phase behavior of water-lipid mesomorphic systems. In spite of extensive research on exploring the mechanism of membrane fusion, a clear molecular understanding of intermediate and pore formation is lacking. In addition, the mechanism by which proteins and peptides reduce the activation energy for stalk and pore formation is not yet clear though there are several propositions on how they catalyze membrane fusion. In this review, we have discussed about various putative functions of fusion peptides by which they reduce activation barrier and thus promote membrane fusion. A careful analysis of the discussed effects of fusion peptides on membranes might open up new possibilities for better understanding of the membrane fusion mechanism.
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237
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Deplazes E, Poger D, Cornell B, Cranfield CG. The effect of hydronium ions on the structure of phospholipid membranes. Phys Chem Chem Phys 2018; 20:357-366. [DOI: 10.1039/c7cp06776c] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
This work studies the mechanisms by which hydronium ions modulate the structure of phospholipid bilayers.
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Affiliation(s)
- Evelyne Deplazes
- School of Biomedical Sciences
- Curtin Health Innovation Research Institute and Curtin Institute for Computation
- Curtin University
- Perth
- Australia
| | - David Poger
- School of Chemistry and Molecular Biosciences
- The University of Queensland
- Brisbane
- Australia
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238
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Hien Nguyen T, C. Moore C, B. Moore P, Liu Z. Molecular dynamics study of homo-oligomeric ion channels: Structures of the surrounding lipids and dynamics of water movement. AIMS BIOPHYSICS 2018. [DOI: 10.3934/biophy.2018.1.50] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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239
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Luan B, Zhou S, Wang D, Zhou R. Detecting Interactions between Nanomaterials and Cell Membranes by Synthetic Nanopores. ACS NANO 2017; 11:12615-12623. [PMID: 29161017 DOI: 10.1021/acsnano.7b07005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Engineered nanomaterials have been increasingly utilized in industry for various consumer products, environmental treatments, energy storage, and biomedical applications. Meanwhile, it has been established that certain nanomaterials can be toxic to biological cells from extensive experimental and theoretical studies. Despite that the exact molecular mechanisms of this nanomaterial toxicity are still not well understood, it is ubiquitous that their interactions with cell membranes, through either endocytosis or penetration (and thus potential lysis), act as the first step toward the inflammation or even the death of a cell. To facilitate the study of nanomaterial-membrane interactions, here we demonstrate a nanopore-based single-molecule approach that can be applied to monitor a specific nanomaterial-membrane interaction in real time. Combined with molecular dynamics and experimental approaches, we show how an ionic current can be used to detect membrane damage by a graphene nanosheet and illustrate the underlying molecular mechanism. More generally, we expect that measured transmembrane ionic currents (both DC and AC) can signify many particle-induced membrane modifications, such as hole formation, particle adsorption, and protein insertion.
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Affiliation(s)
- Binquan Luan
- Computational Biology Center, IBM Thomas J. Watson Research , Yorktown Heights, New York 10598, United States
| | - Shuo Zhou
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences , Chongqing 400714, China
| | - Deqiang Wang
- Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences , Chongqing 400714, China
| | - Ruhong Zhou
- Computational Biology Center, IBM Thomas J. Watson Research , Yorktown Heights, New York 10598, United States
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240
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Atilhan M, Costa LT, Aparicio S. On the behaviour of aqueous solutions of deep eutectic solvents at lipid biomembranes. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2017.09.082] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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241
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Ciumac D, Campbell RA, Clifton LA, Xu H, Fragneto G, Lu JR. Influence of Acyl Chain Saturation on the Membrane-Binding Activity of a Short Antimicrobial Peptide. ACS OMEGA 2017; 2:7482-7492. [PMID: 30023555 PMCID: PMC6044940 DOI: 10.1021/acsomega.7b01270] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 10/12/2017] [Indexed: 05/03/2023]
Abstract
Different bacterial types and their living environments can lead to different saturations in the chains of their membrane lipids. Such structural differences may influence the efficacy of antibiotics that target bacterial membranes. In this work, the effects of acyl chain saturation on the binding of an antimicrobial peptide G4 have been examined as a function of the packing density of lipid monolayers by combining external reflection Fourier transform infrared (ER-FTIR) spectroscopy and neutron reflection (NR) measurements. Langmuir monolayers were formed from 1,2-dipalmitoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DPPG) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (POPG), respectively, with the initial surface pressures controlled at 8 and 28 mN/m. A reduction in the order of the acyl chains associated with the increase in the layer thickness upon G4 binding was revealed from ER-FTIR spectroscopy, with peptide binding reaching equilibration faster in POPG than in DPPG monolayers. Whereas the dynamic DPPG-binding process displayed a steady increase in the amide I band area, the POPG-binding process showed little change in the amide area after the initial period. The peptide amide I area from ER-FTIR spectroscopy could be linearly correlated with the adsorbed G4 amount from NR, irrespective of time, initial pressure, or chain saturation, with clearly more peptide incorporated into the DPPG monolayer. Furthermore, NR revealed that although the peptide was associated with both POPG and DPPG lipid monolayers, it was more extensively distributed in the latter, showing that acyl chain saturation clearly promoted peptide binding and structural disruption.
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Affiliation(s)
- Daniela Ciumac
- Biological
Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Schuster Building, Manchester M13 9PL, U.K.
| | - Richard A. Campbell
- Institute
of Laue Langevin, 71
Avenue des Martyrs, CS-20156, 38042 Grenoble, France
| | | | - Hai Xu
- Centre
for Bioengineering and Biotechnology, China
University of Petroleum, Qingdao 266580, China
| | - Giovanna Fragneto
- Institute
of Laue Langevin, 71
Avenue des Martyrs, CS-20156, 38042 Grenoble, France
| | - Jian R. Lu
- Biological
Physics Laboratory, School of Physics and Astronomy, University of Manchester, Oxford Road, Schuster Building, Manchester M13 9PL, U.K.
- E-mail: . Phone: +44 161 2003926 (J.R.L.)
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242
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Zhang W, Haman KJ, Metzger JM, Hackel BJ, Bates FS, Lodge TP. Quantifying Binding of Ethylene Oxide-Propylene Oxide Block Copolymers with Lipid Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:12624-12634. [PMID: 29068209 PMCID: PMC6055234 DOI: 10.1021/acs.langmuir.7b02279] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Block copolymers composed of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) have been widely used in cell membrane stabilization and permeabilization. To explore the mechanism of interaction between PPO-PEO block copolymers and lipid membranes, we have investigated how polymer structure influences the polymer-lipid bilayer association by varying the overall molecular weight, the hydrophobic and hydrophilic block lengths, and the end-group structure systematically, using 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) unilamellar liposomes as model membranes. Pulsed-field-gradient NMR (PFG-NMR) was employed to probe polymer diffusion in the absence and presence of liposomes. The echo decay curves of free polymers in the absence of liposomes are single exponentials, indicative of simple translational diffusion, while in the presence of liposomes, the decays are biexponential, with the slower decay corresponding to polymers bound to liposomes. The binding percentage of polymer to the liposome was quantified by fitting the echo decay curves to a biexponential model. The NMR experiments show that increasing the total molecular weight and hydrophobicity of the polymer can significantly enhance the polymer-lipid bilayer association, as the binding percentage and liposome surface coverage both increase. We hypothesize that the hydrophobic PPO block inserts into the lipid bilayer due to the fact that little molecular exchange between bound and free polymers occurs on the time scale of the diffusion experiments. Additionally, as polymer concentration increases, the liposome surface coverage increases and approaches a limit. These results demonstrate that PFG-NMR is a simple yet powerful method to quantify interactions between polymers and lipid bilayers.
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Affiliation(s)
- Wenjia Zhang
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Karen J. Haman
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Joseph M. Metzger
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Benjamin J. Hackel
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Frank S. Bates
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Timothy P. Lodge
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
- Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
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243
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Kostritskii AY, Tolmachev DA, Lukasheva NV, Gurtovenko AA. Molecular-Level Insight into the Interaction of Phospholipid Bilayers with Cellulose. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:12793-12803. [PMID: 29040801 DOI: 10.1021/acs.langmuir.7b02297] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Molecular-level insight into the interactions of phospholipid molecules with cellulose is crucial for the development of novel cellulose-based materials for wound dressing. Here we employ the state-of-the-art computer simulations to unlock for the first time the molecular mechanisms behind such interactions. To this end, we performed a series of atomic-scale molecular dynamics simulations of phospholipid bilayers on a crystalline cellulose support at various hydration levels of the bilayer leaflets next to the cellulose surface. Our findings clearly demonstrate the existence of strong interactions between polar lipid head groups and the hydrophilic surface of a cellulose crystal. We identified two major types of interactions between phospholipid molecules and cellulose chains: (i) direct attractive interactions between lipid choline groups and oxygens of hydroxyl (hydroxymethyl) groups of cellulose and (ii) hydrogen bonding between phosphate groups of lipids and cellulose's hydroxymethyl/hydroxyl groups. When the hydration level of the interfacial bilayer/support region is low, these interactions lead to a pronounced asymmetry in the properties of the opposite bilayer leaflets. In particular, the mass density profiles of the proximal leaflets are split into two peaks and lipid head groups become more horizontally oriented with respect to the bilayer surface. Furthermore, the lateral mobility of lipids in the leaflets next to the cellulose surface is found to slow down considerably. Most of these cellulose-induced effects are likely due to hydrogen bonding between lipid phosphate groups and hydroxymethyl/hydroxyl groups of cellulose: the lipid phosphate groups are pulled toward the water/lipid interface due to the formation of hydrogen bonds. Overall, our findings shed light on the molecular details of the interactions between phospholipid bilayers and cellulose nanocrystals and can be used for identifying possible strategies for improving the properties of cellulose-based dressing materials via, e.g., chemical modification of their surface.
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Affiliation(s)
- Andrei Yu Kostritskii
- Faculty of Physics, St. Petersburg State University , Ulyanovskaya str. 3, Petrodvorets, St. Petersburg, 198504 Russia
| | - Dmitry A Tolmachev
- Institute of Macromolecular Compounds, Russian Academy of Sciences , Bolshoi Prospect V.O.31, St. Petersburg, 199004 Russia
| | - Natalia V Lukasheva
- Institute of Macromolecular Compounds, Russian Academy of Sciences , Bolshoi Prospect V.O.31, St. Petersburg, 199004 Russia
| | - Andrey A Gurtovenko
- Institute of Macromolecular Compounds, Russian Academy of Sciences , Bolshoi Prospect V.O.31, St. Petersburg, 199004 Russia
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244
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Ma L, Cai Y, Li Y, Jiao J, Wu Z, O'Shaughnessy B, De Camilli P, Karatekin E, Zhang Y. Single-molecule force spectroscopy of protein-membrane interactions. eLife 2017; 6:30493. [PMID: 29083305 PMCID: PMC5690283 DOI: 10.7554/elife.30493] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 10/29/2017] [Indexed: 12/17/2022] Open
Abstract
Many biological processes rely on protein–membrane interactions in the presence of mechanical forces, yet high resolution methods to quantify such interactions are lacking. Here, we describe a single-molecule force spectroscopy approach to quantify membrane binding of C2 domains in Synaptotagmin-1 (Syt1) and Extended Synaptotagmin-2 (E-Syt2). Syts and E-Syts bind the plasma membrane via multiple C2 domains, bridging the plasma membrane with synaptic vesicles or endoplasmic reticulum to regulate membrane fusion or lipid exchange, respectively. In our approach, single proteins attached to membranes supported on silica beads are pulled by optical tweezers, allowing membrane binding and unbinding transitions to be measured with unprecedented spatiotemporal resolution. C2 domains from either protein resisted unbinding forces of 2–7 pN and had binding energies of 4–14 kBT per C2 domain. Regulation by bilayer composition or Ca2+ recapitulated known properties of both proteins. The method can be widely applied to study protein–membrane interactions.
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Affiliation(s)
- Lu Ma
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China.,Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Yiying Cai
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Yale University School of Medicine, New Haven, United States.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, United States.,Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States
| | - Yanghui Li
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,College of Optical and Electronic Technology, China Jiliang University, Hangzhou, China
| | - Junyi Jiao
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, United States
| | - Zhenyong Wu
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, United States.,Nanobiology Institute, Yale University, West Haven, United States
| | - Ben O'Shaughnessy
- Department of Chemical Engineering, Columbia University, New York, United States
| | - Pietro De Camilli
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States.,Department of Neuroscience, Yale University School of Medicine, New Haven, United States.,Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, United States.,Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, United States.,Kavli Institute for Neuroscience, Yale University School of Medicine, New Haven, United States
| | - Erdem Karatekin
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, United States.,Nanobiology Institute, Yale University, West Haven, United States.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, United States.,Laboratoire de Neurophotonique, Faculté des Sciences Fondamentales et Biomédicales, Centre National de la Recherche Scientifique (CNRS) UMR 8250, Université Paris Descartes, Paris, France
| | - Yongli Zhang
- Department of Cell Biology, Yale University School of Medicine, New Haven, United States
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245
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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.
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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
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246
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Wei C, Pohorille A. Sequence-Dependent Interfacial Adsorption and Permeation of Dipeptides across Phospholipid Membranes. J Phys Chem B 2017; 121:9859-9867. [PMID: 28982244 DOI: 10.1021/acs.jpcb.7b08238] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
We investigate permeation of three blocked dipeptides with different side chain polarity across a phospholipid membrane and their behavior at the water-membrane interface by way of molecular dynamics simulations. Hydrophilic serine-serine dipeptide is found to desorb from the interface to aqueous phase, whereas hydrophobic phenylalanine-leucine and amphiphilic serine-leucine tend to accumulate at the interface with a free energy minimum of -3 kcal/mol. All three dipeptides exhibit free energy barriers to permeation across the membrane located at the center of the bilayer. The height of the barrier is strongly sequence dependent and increases with the dipeptide polarity. It is equal to 3.5, 6.4, and 10.0 kcal/mol for phenylalanine-leucine, serine-leucine, and serine-serine, respectively. The corresponding permeability coefficients are equal to 4.6 × 10-3, 4.5 × 10-5, and 8.7 × 10-8 cm/s. The apparent insensitivity of membrane permeability to hydrophobicity of dipeptides, found in some experiments, is attributed to neglecting corrections for unstirred water layers near membrane surface, which are significant for hydrophobic species. Different hydrophobicity of the dipeptides also influences their conformations and orientations, both at the interface and inside the membrane. In particular, penetration of hydrophilic serine-serine dipeptide causes the formation of water-filled defects in the bilayer. These results are relevant to the delivery of peptide-based therapeutic agents.
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Affiliation(s)
- Chenyu Wei
- NASA Ames Research Center, Mail Stop 239-4, Moffett Field, California 94035, United States.,Department of Pharmaceutical Chemistry, University of California, San Francisco , San Francisco, California 94143, United States
| | - Andrew Pohorille
- NASA Ames Research Center, Mail Stop 239-4, Moffett Field, California 94035, United States.,Department of Pharmaceutical Chemistry, University of California, San Francisco , San Francisco, California 94143, United States
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247
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Molugu TR, Lee S, Brown MF. Concepts and Methods of Solid-State NMR Spectroscopy Applied to Biomembranes. Chem Rev 2017; 117:12087-12132. [PMID: 28906107 DOI: 10.1021/acs.chemrev.6b00619] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Concepts of solid-state NMR spectroscopy and applications to fluid membranes are reviewed in this paper. Membrane lipids with 2H-labeled acyl chains or polar head groups are studied using 2H NMR to yield knowledge of their atomistic structures in relation to equilibrium properties. This review demonstrates the principles and applications of solid-state NMR by unifying dipolar and quadrupolar interactions and highlights the unique features offered by solid-state 2H NMR with experimental illustrations. For randomly oriented multilamellar lipids or aligned membranes, solid-state 2H NMR enables direct measurement of residual quadrupolar couplings (RQCs) due to individual C-2H-labeled segments. The distribution of RQC values gives nearly complete profiles of the segmental order parameters SCD(i) as a function of acyl segment position (i). Alternatively, one can measure residual dipolar couplings (RDCs) for natural abundance lipid samples to obtain segmental SCH order parameters. A theoretical mean-torque model provides acyl-packing profiles representing the cumulative chain extension along the normal to the aqueous interface. Equilibrium structural properties of fluid bilayers and various thermodynamic quantities can then be calculated, which describe the interactions with cholesterol, detergents, peptides, and integral membrane proteins and formation of lipid rafts. One can also obtain direct information for membrane-bound peptides or proteins by measuring RDCs using magic-angle spinning (MAS) in combination with dipolar recoupling methods. Solid-state NMR methods have been extensively applied to characterize model membranes and membrane-bound peptides and proteins, giving unique information on their conformations, orientations, and interactions in the natural liquid-crystalline state.
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Affiliation(s)
- Trivikram R Molugu
- Department of Chemistry & Biochemistry and ‡Department of Physics, University of Arizona , Tucson, Arizona 85721, United States
| | - Soohyun Lee
- Department of Chemistry & Biochemistry and ‡Department of Physics, University of Arizona , Tucson, Arizona 85721, United States
| | - Michael F Brown
- Department of Chemistry & Biochemistry and ‡Department of Physics, University of Arizona , Tucson, Arizona 85721, United States
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248
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Buslaev P, Gushchin I. Effects of Coarse Graining and Saturation of Hydrocarbon Chains on Structure and Dynamics of Simulated Lipid Molecules. Sci Rep 2017; 7:11476. [PMID: 28904383 PMCID: PMC5597592 DOI: 10.1038/s41598-017-11761-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 08/25/2017] [Indexed: 12/14/2022] Open
Abstract
Molecular dynamics simulations are used extensively to study the processes on biological membranes. The simulations can be conducted at different levels of resolution: all atom (AA), where all atomistic details are provided; united atom (UA), where hydrogen atoms are treated inseparably of corresponding heavy atoms; and coarse grained (CG), where atoms are grouped into larger particles. Here, we study the behavior of model bilayers consisting of saturated and unsaturated lipids DOPC, SOPC, OSPC and DSPC in simulations performed using all atom CHARMM36 and coarse grained Martini force fields. Using principal components analysis, we show that the structural and dynamical properties of the lipids are similar, both in AA and CG simulations, although the unsaturated molecules are more dynamic and favor more extended conformations. We find that CG simulations capture 75 to 100% of the major collective motions, overestimate short range ordering, result in more flexible molecules and 5–7 fold faster sampling. We expect that the results reported here will be useful for comprehensive quantitative comparisons of simulations conducted at different resolution levels and for further development and improvement of CG force fields.
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Affiliation(s)
- Pavel Buslaev
- Moscow Institute of Physics and Technology, 141700, Dolgoprudny, Russia.
| | - Ivan Gushchin
- Moscow Institute of Physics and Technology, 141700, Dolgoprudny, Russia. .,Institute of Complex Systems (ICS), ICS-6: Structural Biochemistry, Research Centre Jülich, 52425, Jülich, Germany.
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249
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Doi H, Okuwaki K, Mochizuki Y, Ozawa T, Yasuoka K. Dissipative particle dynamics (DPD) simulations with fragment molecular orbital (FMO) based effective parameters for 1-Palmitoyl-2-oleoyl phosphatidyl choline (POPC) membrane. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.07.032] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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250
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Tunuguntla RH, Henley RY, Yao YC, Pham TA, Wanunu M, Noy A. Enhanced water permeability and tunable ion selectivity in subnanometer carbon nanotube porins. Science 2017; 357:792-796. [DOI: 10.1126/science.aan2438] [Citation(s) in RCA: 409] [Impact Index Per Article: 58.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 07/11/2017] [Indexed: 12/26/2022]
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