1
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Struts AV, Barmasov AV, Fried SDE, Hewage KSK, Perera SMDC, Brown MF. Osmotic stress studies of G-protein-coupled receptor rhodopsin activation. Biophys Chem 2024; 304:107112. [PMID: 37952496 DOI: 10.1016/j.bpc.2023.107112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Revised: 09/22/2023] [Accepted: 09/24/2023] [Indexed: 11/14/2023]
Abstract
We summarize and critically review osmotic stress studies of the G-protein-coupled receptor rhodopsin. Although small amounts of structural water are present in these receptors, the effect of bulk water on their function remains uncertain. Studies of the influences of osmotic stress on the GPCR archetype rhodopsin have given insights into the functional role of water in receptor activation. Experimental work has discovered that osmolytes shift the metarhodopsin equilibrium after photoactivation, either to the active or inactive conformations according to their molar mass. At least 80 water molecules are found to enter rhodopsin in the transition to the photoreceptor active state. We infer that this movement of water is both necessary and sufficient for receptor activation. If the water influx is prevented, e.g., by large polymer osmolytes or by dehydration, then the receptor functional transition is back shifted. These findings imply a new paradigm in which rhodopsin becomes solvent swollen in the activation mechanism. Water thus acts as an allosteric modulator of function for rhodopsin-like receptors in lipid membranes.
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Affiliation(s)
- Andrey V Struts
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA; Laboratory of Biomolecular NMR, St.-Petersburg State University, 199034 St.-Petersburg, Russia
| | - Alexander V Barmasov
- Department of Biophysics, St.-Petersburg State Pediatric Medical University, 194100 St.-Petersburg, Russia; Department of Physics, St.-Petersburg State University, 199034 St.-Petersburg, Russia
| | - Steven D E Fried
- Department of Chemistry, Stanford University, Stanford, CA 94305, USA
| | - Kushani S K Hewage
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | | | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA; Department of Physics, University of Arizona, Tucson, AZ 85721, USA.
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2
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Kumar A, Daschakraborty S. Anomalous lateral diffusion of lipids during the fluid/gel phase transition of a lipid membrane. Phys Chem Chem Phys 2023; 25:31431-31443. [PMID: 37962400 DOI: 10.1039/d3cp04081j] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
A lipid membrane undergoes a phase transition from fluid to gel phase upon changing external thermodynamic conditions, such as decreasing temperature and increasing pressure. Extremophilic organisms face the challenge of preventing this deleterious phase transition. The main focus of their adaptive strategy is to facilitate effective temperature sensing through sensor proteins, relying on the drastic changes in packing density and membrane fluidity during the phase transition. Although the changes in packing density parameters due to the fluid/gel phase transition are studied in detail, the impact on membrane fluidity is less explored in the literature. Understanding the lateral diffusive dynamics of lipids in response to temperature, particularly during the fluid/gel phase transition, is albeit crucial. Here we have simulated the phase transition of a single component lipid membrane composed of dipalmitoylphosphatidylcholine (DPPC) lipids using a coarse-grained (CG) model and studied the changes of the structural and dynamical properties. It is observed that near the phase transition point, both fluid and gel phase domains coexist together. The dynamics remains highly non-Gaussian for a long time even when the mean square displacement reaches the Fickian regime at a much earlier time. This Fickian yet non-Gaussian diffusion (FnGD) is a characteristic of a highly heterogeneous system, previously observed for the lateral diffusion of lipids in raft mimetic membranes having liquid-ordered and liquid-disordered phases co-existing together. We have analyzed the molecular trajectories and calculated the jump-diffusion of the lipids, stemming from sudden jump translations, using a translational jump-diffusion (TJD) approach. An overwhelming contribution of the jump-diffusion of the lipids is observed suggesting anomalous diffusion of lipids during fluid/gel phase transition of the membrane. These results are important in unravelling the intricate nature of lipid diffusion during the phase transition of the membrane and open up a new possibility of investigating the most significant change of membrane properties during phase transition, which can be effectively sensed by proteins.
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Affiliation(s)
- Abhay Kumar
- Department of Chemistry, Indian Institute of Technology Patna, Bihar 801106, India.
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3
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Karal MAS, Billah MM, Ahmed M, Ahamed MK. A review on the measurement of the bending rigidity of lipid membranes. SOFT MATTER 2023; 19:8285-8304. [PMID: 37873600 DOI: 10.1039/d3sm00882g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
This review provides an overview of the latest developments in both experimental and simulation techniques used to assess the bending rigidity of lipid membranes. It places special emphasis on experimental methods that utilize model vesicles to manipulate lipid compositions and other experimental parameters to determine the bending rigidity of the membrane. It also describes two commonly used simulation methods for estimating bending rigidity. The impact of various factors on membrane bending rigidity is summarized, including cholesterol, lipids, salt concentration, surface charge, membrane phase state, peptides, proteins, and polyethylene glycol. These factors are shown to influence the bending rigidity, contributing to a better understanding of the biophysical properties of membranes and their role in biological processes. Furthermore, the review discusses future directions and potential advancements in this research field, highlighting areas where further investigation is required.
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Affiliation(s)
- Mohammad Abu Sayem Karal
- Department of Physics, Bangladesh University of Engineering and Technology, Dhaka 1000, Bangladesh.
| | - Md Masum Billah
- Department of Physics, Jashore University of Science and Technology, Jashore 7408, Bangladesh
| | - Marzuk Ahmed
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan
| | - Md Kabir Ahamed
- Radiation, Transport and Waste Safety Division, Bangladesh Atomic Energy Regulatory Authority, Agargaon, Dhaka 1207, Bangladesh
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4
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Doktorova M, Khelashvili G, Ashkar R, Brown MF. Molecular simulations and NMR reveal how lipid fluctuations affect membrane mechanics. Biophys J 2023; 122:984-1002. [PMID: 36474442 PMCID: PMC10111610 DOI: 10.1016/j.bpj.2022.12.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 11/21/2022] [Accepted: 12/02/2022] [Indexed: 12/07/2022] Open
Abstract
Lipid bilayers form the main matrix of functional cell membranes, and their dynamics underlie a host of physical and biological processes. Here we show that elastic membrane properties and collective molecular dynamics (MD) are related by the mean-square amplitudes (order parameters) and relaxation rates (correlation times) of lipid acyl chain motions. We performed all-atom MD simulations of liquid-crystalline bilayers that allow direct comparison with carbon-hydrogen (CH) bond relaxations measured with NMR spectroscopy. Previous computational and theoretical approaches have assumed isotropic relaxation, which yields inaccurate description of lipid chain dynamics and incorrect data interpretation. Instead, the new framework includes a fixed bilayer normal (director axis) and restricted anisotropic motion of the CH bonds in accord with their segmental order parameters, enabling robust validation of lipid force fields. Simulated spectral densities of thermally excited CH bond fluctuations exhibited well-defined spin-lattice (Zeeman) relaxations analogous to those in NMR measurements. Their frequency signature could be fit to a simple power-law function, indicative of nematic-like collective dynamics. Moreover, calculated relaxation rates scaled as the squared order parameters yielding an apparent κC modulus for bilayer bending. Our results show a strong correlation with κC values obtained from solid-state NMR studies of bilayers without and with cholesterol as validated by neutron spin-echo measurements of membrane elasticity. The simulations uncover a critical role of interleaflet coupling in membrane mechanics and thus provide important insights into molecular sites of emerging elastic properties within lipid bilayers.
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Affiliation(s)
- Milka Doktorova
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia.
| | - George Khelashvili
- Department of Physiology and Biophysics, Weill Cornell Medical College of Cornell University, New York, New York; Institute of Computational Biomedicine, Weill Cornell Medical College of Cornell University, New York, New York
| | - Rana Ashkar
- Department of Physics, Virginia Tech, Blacksburg, Virginia; Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, Virginia
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona; Department of Physics, University of Arizona, Tucson, Arizona; Program in Applied Mathematics, University of Arizona, Tucson, Arizona.
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5
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Won T, Mohid SA, Choi J, Kim M, Krishnamoorthy J, Biswas I, Bhunia A, Lee D. The role of hydrophobic patches of de novo designed MSI-78 and VG16KRKP antimicrobial peptides on fragmenting model bilayer membranes. Biophys Chem 2023; 296:106981. [PMID: 36871366 DOI: 10.1016/j.bpc.2023.106981] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 02/06/2023] [Accepted: 02/21/2023] [Indexed: 02/26/2023]
Abstract
Antimicrobial peptides (AMPs) with cell membrane lysing capability are considered potential candidates for the development of the next generation of antibiotics. Designing novel AMPs requires an in-depth understanding of the mechanism of action of the peptides. In this work, we used various biophysical techniques including 31P solid-state NMR to examine the interaction of model membranes with amphipathic de novo-designed peptides. Two such peptides, MSI-78 and VG16KRKP, were designed with different hydrophobicity and positive charges. The model lipid membranes were constituted by mixing lipids of varying degrees of 'area per lipid' (APL), which directly affected the packing properties of the membrane. The observed emergence of the isotropic peak in 31P NMR spectra as a function of time is a consequence of the fragmentation of the membrane mediated by the peptide interaction. The factors such as the charges, overall hydrophilicity of the AMPs, as well as lipid membrane packing, contributed to the kinetics of membrane fragmentation. Furthermore, we anticipate the designed AMPs follow the carpet and toroidal pore mechanisms when lysing the cell membrane. This study highlights the significance of the effect of the overall charges and the hydrophobicity of the novel AMPs designed for antimicrobial activity.
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Affiliation(s)
- TaeJun Won
- Department of Fine Chemistry, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - Sk Abdul Mohid
- Department of Biophysics, Bose Institute, Unified Academic Campus, Bidhan Nagar EN 80, Kolkata 700 091, India
| | - JiHye Choi
- Department of Fine Chemistry, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | - MinSoo Kim
- Department of Fine Chemistry, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
| | | | - Indranil Biswas
- Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, KS 66160, USA
| | - Anirban Bhunia
- Department of Biophysics, Bose Institute, Unified Academic Campus, Bidhan Nagar EN 80, Kolkata 700 091, India.
| | - DongKuk Lee
- Department of Fine Chemistry, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea.
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6
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Moss FR, Lincoff J, Tucker M, Mohammed A, Grabe M, Frost A. Brominated lipid probes expose structural asymmetries in constricted membranes. Nat Struct Mol Biol 2023; 30:167-175. [PMID: 36624348 PMCID: PMC9935397 DOI: 10.1038/s41594-022-00898-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 11/11/2022] [Indexed: 01/11/2023]
Abstract
Lipids in biological membranes are thought to be functionally organized, but few experimental tools can probe nanoscale membrane structure. Using brominated lipids as contrast probes for cryo-EM and a model ESCRT-III membrane-remodeling system composed of human CHMP1B and IST1, we observed leaflet-level and protein-localized structural lipid patterns within highly constricted and thinned membrane nanotubes. These nanotubes differed markedly from protein-free, flat bilayers in leaflet thickness, lipid diffusion rates and lipid compositional and conformational asymmetries. Simulations and cryo-EM imaging of brominated stearoyl-docosahexanenoyl-phosphocholine showed how a pair of phenylalanine residues scored the outer leaflet with a helical hydrophobic defect where polyunsaturated docosahexaenoyl tails accumulated at the bilayer surface. Combining cryo-EM of halogenated lipids with molecular dynamics thus enables new characterizations of the composition and structure of membranes on molecular length scales.
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Affiliation(s)
- Frank R Moss
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Altos Labs, Redwood City, CA, USA
| | - James Lincoff
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, USA
- Cardiovascular Research Institute, University of California San Francisco (UCSF), San Francisco, CA, USA
| | - Maxwell Tucker
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, USA
- Cardiovascular Research Institute, University of California San Francisco (UCSF), San Francisco, CA, USA
| | - Arshad Mohammed
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
- University of California Berkeley, Berkeley, CA, USA
- Altos Labs, Redwood City, CA, USA
| | - Michael Grabe
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, USA.
- Cardiovascular Research Institute, University of California San Francisco (UCSF), San Francisco, CA, USA.
| | - Adam Frost
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA.
- Altos Labs, Redwood City, CA, USA.
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7
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Doole FT, Gupta S, Kumarage T, Ashkar R, Brown MF. Biophysics of Membrane Stiffening by Cholesterol and Phosphatidylinositol 4,5-bisphosphate (PIP2). ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:61-85. [PMID: 36988877 DOI: 10.1007/978-3-031-21547-6_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Cell membranes regulate a wide range of phenomena that are implicated in key cellular functions. Cholesterol, a critical component of eukaryotic cell membranes, is responsible for cellular organization, membrane elasticity, and other critical physicochemical parameters. Besides cholesterol, other lipid components such as phosphatidylinositol 4,5-bisphosphate (PIP2) are found in minor concentrations in cell membranes yet can also play a major regulatory role in various cell functions. In this chapter, we describe how solid-state deuterium nuclear magnetic resonance (2H NMR) spectroscopy together with neutron spin-echo (NSE) spectroscopy can inform synergetic changes to lipid molecular packing due to cholesterol and PIP2 that modulate the bending rigidity of lipid membranes. Fundamental structure-property relations of molecular self-assembly are illuminated and point toward a length and time-scale dependence of cell membrane mechanics, with significant implications for biological activity and membrane lipid-protein interactions.
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Affiliation(s)
- Fathima T Doole
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA
| | - Sudipta Gupta
- Department of Physics and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, USA
| | - Teshani Kumarage
- Department of Physics and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, USA
| | - Rana Ashkar
- Department of Physics and Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, USA.
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA.
- Department of Physics, University of Arizona, Tucson, AZ, USA.
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8
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Molugu TR, Thurmond RL, Alam TM, Trouard TP, Brown MF. Phospholipid headgroups govern area per lipid and emergent elastic properties of bilayers. Biophys J 2022; 121:4205-4220. [PMID: 36088534 PMCID: PMC9674990 DOI: 10.1016/j.bpj.2022.09.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 08/10/2022] [Accepted: 09/06/2022] [Indexed: 11/24/2022] Open
Abstract
Phospholipid bilayers are liquid-crystalline materials whose intermolecular interactions at mesoscopic length scales have key roles in the emergence of membrane physical properties. Here we investigated the combined effects of phospholipid polar headgroups and acyl chains on biophysical functions of membranes with solid-state 2H NMR spectroscopy. We compared the structural and dynamic properties of phosphatidylethanolamine and phosphatidylcholine with perdeuterated acyl chains in the solid-ordered (so) and liquid-disordered (ld) phases. Our analysis of spectral lineshapes of 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE-d62) and 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphocholine (DPPC-d62) in the so (gel) phase indicated an all-trans rotating chain structure for both lipids. Greater segmental order parameters (SCD) were observed in the ld (liquid-crystalline) phase for DPPE-d62 than for DPPC-d62 membranes, while their mixtures had intermediate values irrespective of the deuterated lipid type. Our results suggest the SCD profiles of the acyl chains are governed by methylation of the headgroups and are averaged over the entire system. Variations in the acyl chain molecular dynamics were further investigated by spin-lattice (R1Z) and quadrupolar-order relaxation (R1Q) measurements. The two acyl-perdeuterated lipids showed distinct differences in relaxation behavior as a function of the order parameter. The R1Z rates had a square-law dependence on SCD, implying collective mesoscopic dynamics, with a higher bending rigidity for DPPE-d62 than for DPPC-d62 lipids. Remodeling of lipid average and dynamic properties by methylation of the headgroups thus provides a mechanism to control the actions of peptides and proteins in biomembranes.
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Affiliation(s)
- Trivikram R Molugu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | | | - Todd M Alam
- Department of Organic Materials Science, Sandia National Laboratories, Albuquerque, New Mexico
| | - Theodore P Trouard
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona; Department of Physics, University of Arizona, Tucson, Arizona.
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9
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Doole FT, Kumarage T, Ashkar R, Brown MF. Cholesterol Stiffening of Lipid Membranes. J Membr Biol 2022; 255:385-405. [PMID: 36219221 PMCID: PMC9552730 DOI: 10.1007/s00232-022-00263-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Accepted: 08/05/2022] [Indexed: 11/30/2022]
Abstract
Biomembrane order, dynamics, and other essential physicochemical parameters are controlled by cholesterol, a major component of mammalian cell membranes. Although cholesterol is well known to exhibit a condensing effect on fluid lipid membranes, the extent of stiffening that occurs with different degrees of lipid acyl chain unsaturation remains an enigma. In this review, we show that cholesterol locally increases the bending rigidity of both unsaturated and saturated lipid membranes, suggesting there may be a length-scale dependence of the bending modulus. We review our published data that address the origin of the mechanical effects of cholesterol on unsaturated and polyunsaturated lipid membranes and their role in biomembrane functions. Through a combination of solid-state deuterium NMR spectroscopy and neutron spin-echo spectroscopy, we show that changes in molecular packing cause the universal effects of cholesterol on the membrane bending rigidity. Our findings have broad implications for the role of cholesterol in lipid–protein interactions as well as raft-like mixtures, drug delivery applications, and the effects of antimicrobial peptides on lipid membranes.
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Affiliation(s)
- Fathima T Doole
- Deaprtment of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85712, USA
| | - Teshani Kumarage
- Department of Physics, Virginia Tech, Blacksburg, VA, 24061, USA.,Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Rana Ashkar
- Department of Physics, Virginia Tech, Blacksburg, VA, 24061, USA. .,Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, 24061, USA.
| | - Michael F Brown
- Deaprtment of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, 85712, USA. .,Department of Physics, University of Arizona, Tucson, AZ, 85712, USA.
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10
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Hanashima S, Mito K, Umegawa Y, Murata M, Hojo H. Lipid chain-driven interaction of a lipidated Src-family kinase Lyn with the bilayer membrane. Org Biomol Chem 2022; 20:6436-6444. [PMID: 35880995 DOI: 10.1039/d2ob01079h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
N-Myristoylation is a process of ubiquitous protein modification, which promotes the interaction of lipidated proteins on cell surfaces, in conjunction with reversible S-palmitoylation. We report the cooperative lipid-lipid interaction of two acyl chains of proteins, which increases the protein-membrane interaction and facilitates selective targeting of membranes containing anionic lipids. Lyn is a member of the Src family kinases distributed on the membrane surface by N-myristoyl and neighbouring S-palmitoyl chain anchors at the unique N-terminus domain. We prepared N-terminal short segments of lipidated Lyn to investigate the behaviour of each acyl chain in the lipid composition-dependent membrane interaction by solid-state nuclear magnetic resonance (NMR) analysis. Solid-state 31P-NMR studies revealed that S-palmitoylation of N-myristoylated Lyn peptides increased the interaction between peptides and phospholipid head groups, particularly with the anionic phosphatidylserine-containing bilayers. The solid-state 2H-NMR of Lyn peptides with a perdeutero N-myristoyl chain indicated an increase (0.6-0.8 Å) in the extent of the N-myristoyl chain in the presence of nearby S-palmitoyl chains, probably through the interaction via the acyl chains. The cooperative hydrocarbon chain interaction of the two acyl chains of Lyn increased membrane binding by extending the hydrocarbon chains deeper into the membrane interior, thereby promoting the peptide-membrane surface interaction between the cationic peptide side chains and the anionic lipid head groups. This lipid-driven mechanism by S-palmitoylation promotes the partition of the lipidated proteins to the cytoplasmic surface of the cell membranes and may be involved in recruiting Lyn at the signalling domains rich in anionic lipids.
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Affiliation(s)
- Shinya Hanashima
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
| | - Kanako Mito
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
| | - Yuichi Umegawa
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
| | - Michio Murata
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan. .,Forefront Research Center, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Hironobu Hojo
- Forefront Research Center, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.,Institute for Protein Research, Osaka University, Yamadaoka 3-2, Suita 565-0871, Japan
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11
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Pharma 4.0 Continuous mRNA Drug Products Manufacturing. Pharmaceutics 2021; 13:pharmaceutics13091371. [PMID: 34575447 PMCID: PMC8466472 DOI: 10.3390/pharmaceutics13091371] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/23/2021] [Accepted: 08/27/2021] [Indexed: 01/13/2023] Open
Abstract
Continuous mRNA drugs manufacturing is perceived to nurture flow processes featuring quality by design, controlled automation, real time validation, robustness, and reproducibility, pertaining to regulatory harmonization. However, the actual adaptation of the latter remains elusive, hence batch-to-continuous transition would a priori necessitate holistic process understanding. In addition, the cost related to experimental, pilot manufacturing lines development and operations thereof renders such venture prohibitive. Systems-based Pharmaceutics 4.0 digital design enabling tools, i.e., converging mass and energy balance simulations, Monte-Carlo machine learning iterations, and spatial arrangement analysis were recruited herein to overcome the aforementioned barriers. The primary objective of this work is to hierarchically design the related bioprocesses, embedded in scalable devices, compatible with continuous operation. Our secondary objective is to harvest the obtained technological data and conduct resource commitment analysis. We herein demonstrate for first time the feasibility of the continuous, end-to-end production of sterile mRNA formulated into lipid nanocarriers, defining the equipment specifications and the desired operational space. Moreover, we find that the cell lysis modules and the linearization enzymes ascend as the principal resource-intensive model factors, accounting for 40% and 42% of the equipment and raw material, respectively. We calculate MSPD 1.30–1.45 €, demonstrating low margin lifecycle fluctuation.
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12
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Kumar N, Sastry GN. Study of lipid heterogeneity on bilayer membranes using molecular dynamics simulations. J Mol Graph Model 2021; 108:108000. [PMID: 34365255 DOI: 10.1016/j.jmgm.2021.108000] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 07/17/2021] [Accepted: 07/29/2021] [Indexed: 11/26/2022]
Abstract
Human cell membranes consist of various lipids that are essential for their structure and function. It typically comprises phosphatidylcholine (POPC), phosphatidylethanolamine (POPE), phosphatidylserine (POPS), sphingomyelin (PSM), and cholesterol (CHL). Several experimental and computational techniques have been employed to characterize the composition of human cell membranes, however, CHL enriched membrane is still not clearly understood through these techniques. Molecular dynamics simulation results illustrated the biophysical properties of heterogeneous membranes based on the lipid composition as well as the concentration of lipids, exclusively for CHL and PSM. Herein, we have investigated the structure-function relationships of lipids comparatively to delineate the effect of heterogeneity on the biophysical properties of different membranes. It has been observed that the significant fraction of CHL (i.e., ~33% in ternary, ~25% in quaternary, and ~16% in senary type bilayers) in combination with other lipids introduced compactness, and increased the thickness of the membrane. The analysis of lipid mass density stated that the density of lipid head group, phosphate, and glycerol-ester in presence of CHL with or without PSM is an underlying reason for membrane ordering. Results also revealed that the presence of POPI and POPS are the reasons for an adequate drop in the ordering of lipid chain, particularly on POPE chain. The self-interaction of CHL, PSM, POPE and the interaction of CHL and POPC with POPE seem to determine the structure and function of the heterogeneous membrane. Our findings provide a qualitative understanding of the effect of membrane heterogeneity on the physiological properties of membranes. The structures inspected in this study would help to select the heterogeneous bilayer model to mimic the human cell membranes to analyse or characterize the membrane-associated phenomena.
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Affiliation(s)
- Nandan Kumar
- Centre for Molecular Modelling, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad, 500007, Telangana State, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, U. P., India
| | - G Narahari Sastry
- Centre for Molecular Modelling, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad, 500007, Telangana State, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, U. P., India; Advanced Computation and Data Sciences Division, CSIR-North East Institute of Science and Technology, Jorhat, 785006, Assam, India.
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13
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Dziubak D, Sek S. Physicochemical Characterization of Sparsely Tethered Bilayer Lipid Membranes: Structure of Submembrane Water and Nanomechanical Properties. ChemElectroChem 2021. [DOI: 10.1002/celc.202100721] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Damian Dziubak
- Faculty of Chemistry, Biological & Chemical Research Centre University of Warsaw Zwirki i Wigury 101 02-089 Warsaw Poland
| | - Slawomir Sek
- Faculty of Chemistry, Biological & Chemical Research Centre University of Warsaw Zwirki i Wigury 101 02-089 Warsaw Poland
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14
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Müller JP, Keufgens L, Gründemann D. Hyperosmolarity stimulates transporter-mediated insertion of estrone sulfate into the plasma membrane, but inhibits the uptake by SLC10A1 (NTCP). Biochem Pharmacol 2021; 186:114484. [PMID: 33617845 DOI: 10.1016/j.bcp.2021.114484] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 02/17/2021] [Accepted: 02/17/2021] [Indexed: 12/13/2022]
Abstract
Many drugs are largely hydrophobic molecules; a transporter might conceivably insert these into the plasma membrane. At least 18 transporters from diverse families have been reported to transport the model compound estrone sulfate alias estrone-3-sulfate (E3S). Out of these, we recently examined SLC22A11 (OAT4). We concluded from a comparison of E3S and uric acid transport that SLC22A11 does not translocate E3S into the cytosol, but into the plasma membrane. Here we present a hyperosmolarity alias hypertonicity assay to differentiate transport mechanisms. Human transporters were expressed heterologously in 293 cells. Solute uptake into intact cells was measured by LC-MS. Addition of mannitol or sucrose led to rapid cell shrinkage, but cell viability after 60 min in hyperosmolar buffer was not impaired. A decrease in substrate accumulation with increasing osmolarity as observed here for several substrates and the transporters SLC22A11, ETT (SLC22A4), OCT2 (SLC22A2), OAT3 (SLC22A8), and MATE1 (SLC47A1) suggests regular substrate translocation into the cytosol. An increase as observed for E3S transport by SLC22A11, OAT3, MATE1, SLC22A9, and SLC10A6 implies insertion into the membrane. In marked contrast to the other E3S transporters, the bile acid transporter SLC10A1 (NTCP, Na+ taurocholate co-transporting polypeptide) showed a decrease in the accumulation of E3S in hyperosmolar buffer; the same was observed with taurocholic acid. Indeed, our data from several functional assays strongly suggest that the transport mechanism is identical for both substrates. Apparently, a unique transport mechanism has been established for SLC10A1 by evolution that ensures the transport of amphipathic, detergent-like molecules into the cytosol.
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Affiliation(s)
- Julian Peter Müller
- Department of Pharmacology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Gleueler Straße 24, Cologne 50931, Germany
| | - Lena Keufgens
- Department of Pharmacology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Gleueler Straße 24, Cologne 50931, Germany
| | - Dirk Gründemann
- Department of Pharmacology, University of Cologne, Faculty of Medicine and University Hospital Cologne, Gleueler Straße 24, Cologne 50931, Germany.
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15
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Membrane Curvature Revisited-the Archetype of Rhodopsin Studied by Time-Resolved Electronic Spectroscopy. Biophys J 2020; 120:440-452. [PMID: 33217383 DOI: 10.1016/j.bpj.2020.11.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/01/2020] [Accepted: 11/10/2020] [Indexed: 12/13/2022] Open
Abstract
G-protein-coupled receptors (GPCRs) comprise the largest and most pharmacologically targeted membrane protein family. Here, we used the visual receptor rhodopsin as an archetype for understanding membrane lipid influences on conformational changes involved in GPCR activation. Visual rhodopsin was recombined with lipids varying in their degree of acyl chain unsaturation and polar headgroup size using 1-palmitoyl-2-oleoyl-sn-glycero- and 1,2-dioleoyl-sn-glycerophospholipids with phosphocholine (PC) or phosphoethanolamine (PE) substituents. The receptor activation profile after light excitation was measured using time-resolved ultraviolet-visible spectroscopy. We discovered that more saturated POPC lipids back shifted the equilibrium to the inactive state, whereas the small-headgroup, highly unsaturated DOPE lipids favored the active state. Increasing unsaturation and decreasing headgroup size have similar effects that combine to yield control of rhodopsin activation, and necessitate factors beyond proteolipid solvation energy and bilayer surface electrostatics. Hence, we consider a balance of curvature free energy with hydrophobic matching and demonstrate how our data support a flexible surface model (FSM) for the coupling between proteins and lipids. The FSM is based on the Helfrich formulation of membrane bending energy as we previously first applied to lipid-protein interactions. Membrane elasticity and curvature strain are induced by lateral pressure imbalances between the constituent lipids and drive key physiological processes at the membrane level. Spontaneous negative monolayer curvature toward water is mediated by unsaturated, small-headgroup lipids and couples directly to GPCR activation upon light absorption by rhodopsin. For the first time to our knowledge, we demonstrate this modulation in both the equilibrium and pre-equilibrium evolving states using a time-resolved approach.
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16
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Mostofian B, Johnson QR, Smith JC, Cheng X. Carotenoids promote lateral packing and condensation of lipid membranes. Phys Chem Chem Phys 2020; 22:12281-12293. [PMID: 32432296 DOI: 10.1039/d0cp01031f] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Carotenoids are pigment molecules that protect biomembranes against degradation and may be involved in the formation of functional bacterial membrane microdomains. Little is known on whether different types of carotenoids have different effects on the membrane or if there is any concentration dependence of these effects. In this work, we present results from molecular dynamics simulations of phospholipid bilayers containing different amounts of either β-carotene or zeaxanthin. Both β-carotene and zeaxanthin show the ability to laterally condense the membrane lipids and reduce their inter-leaflet interactions. With increasing concentrations, both carotenoids increase the bilayer thickness and rigidity. The results reveal that carotenoids have similar effects to cholesterol on regulating the behavior of fluid-phase membranes, suggesting that they could function as sterol substitutes and confirming their potential role in the formation of functional membrane domains.
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Affiliation(s)
- Barmak Mostofian
- Center for Molecular Biophysics, Oak Ridge National Lab, Oak Ridge, TN 37830, USA.
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17
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Drabik D, Chodaczek G, Kraszewski S, Langner M. Mechanical Properties Determination of DMPC, DPPC, DSPC, and HSPC Solid-Ordered Bilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:3826-3835. [PMID: 32176506 PMCID: PMC7467745 DOI: 10.1021/acs.langmuir.0c00475] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Lipid bilayers are active participants in many crucial biological processes. They can be observed in different phases, liquid and solid, respectively. The liquid phase is predominant in biological systems. The solid phase, both crystalline and gel phases, is under investigation due to its resilience to mechanical stress and tight packing of lipids. The mechanical properties of lipids affect their dynamics, therefore influencing the transformation of cell plasma and the endomembrane. Mechanical properties of lipid bilayers are also an important parameter in the design and production of supramolecular lipid-based drug delivery systems. To this end, in this work, we focused on investigating the effect of solid phases of lipid bilayers on their structural parameters and mechanical properties using theoretical molecular dynamics studies on atomistic models of whole vesicles. Those include area per lipid, membrane thickness, density vesicle profiles, bending rigidity coefficient, and area compressibility. Additionally, the bending rigidity coefficient was measured using the flicker noise spectroscopy. The two approaches produced very similar and consistent results. We showed that, contrary to our expectations, bending rigidity coefficients of solid-ordered bilayers for vesicles decreased with an increase in lipid transition temperature. This tendency was reverse in planar systems. Additionally, we have observed an increase of membrane thickness and area compressibility and a decrease of area per lipid. We hope these results will provide valuable mechanical insight for the behavior in solid phases and differences between spherical and planar confirmations.
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Affiliation(s)
- Dominik Drabik
- Department of Biomedical
Engineering, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Pl. Grunwaldzki 13, 50-377 Wrocław, Poland
| | - Grzegorz Chodaczek
- PORT − Polish Center for Technology Development, Stabłowicka 147, 54-066 Wrocław, Poland
| | - Sebastian Kraszewski
- Department of Biomedical
Engineering, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Pl. Grunwaldzki 13, 50-377 Wrocław, Poland
| | - Marek Langner
- Department of Biomedical
Engineering, Faculty of Fundamental Problems of Technology, Wrocław University of Science and Technology, Pl. Grunwaldzki 13, 50-377 Wrocław, Poland
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18
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Singh M, Kumar V, Sikka K, Thakur R, Harioudh MK, Mishra DP, Ghosh JK, Siddiqi MI. Computational Design of Biologically Active Anticancer Peptides and Their Interactions with Heterogeneous POPC/POPS Lipid Membranes. J Chem Inf Model 2019; 60:332-341. [DOI: 10.1021/acs.jcim.9b00348] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Maninder Singh
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India
| | - Vikash Kumar
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India
| | - Kamakshi Sikka
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India
| | - Ravi Thakur
- Endocrinology Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India
| | - Munesh Kumar Harioudh
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India
| | - Durga Prasad Mishra
- Endocrinology Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India
| | - Jimut Kanti Ghosh
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India
| | - Mohammad Imran Siddiqi
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute (CSIR-CDRI), Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India
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19
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Yamagami M, Tsuchikawa H, Cui J, Umegawa Y, Miyazaki Y, Seo S, Shinoda W, Murata M. Average Conformation of Branched Chain Lipid PGP-Me That Accounts for the Thermal Stability and High-Salinity Resistance of Archaeal Membranes. Biochemistry 2019; 58:3869-3879. [DOI: 10.1021/acs.biochem.9b00469] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Masaki Yamagami
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
- JST ERATO, Lipid Active Structure Project, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Hiroshi Tsuchikawa
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Jin Cui
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
- JST ERATO, Lipid Active Structure Project, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Yuichi Umegawa
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
- JST ERATO, Lipid Active Structure Project, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
| | - Yusuke Miyazaki
- Department of Materials Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Sangjae Seo
- Department of Materials Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Wataru Shinoda
- Department of Materials Chemistry, Graduate School of Engineering, Nagoya University, Nagoya 464-8603, Japan
| | - Michio Murata
- Department of Chemistry, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
- JST ERATO, Lipid Active Structure Project, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
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20
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Marrink SJ, Corradi V, Souza PC, Ingólfsson HI, Tieleman DP, Sansom MS. Computational Modeling of Realistic Cell Membranes. Chem Rev 2019; 119:6184-6226. [PMID: 30623647 PMCID: PMC6509646 DOI: 10.1021/acs.chemrev.8b00460] [Citation(s) in RCA: 410] [Impact Index Per Article: 82.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Indexed: 12/15/2022]
Abstract
Cell membranes contain a large variety of lipid types and are crowded with proteins, endowing them with the plasticity needed to fulfill their key roles in cell functioning. The compositional complexity of cellular membranes gives rise to a heterogeneous lateral organization, which is still poorly understood. Computational models, in particular molecular dynamics simulations and related techniques, have provided important insight into the organizational principles of cell membranes over the past decades. Now, we are witnessing a transition from simulations of simpler membrane models to multicomponent systems, culminating in realistic models of an increasing variety of cell types and organelles. Here, we review the state of the art in the field of realistic membrane simulations and discuss the current limitations and challenges ahead.
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Affiliation(s)
- Siewert J. Marrink
- Groningen
Biomolecular Sciences and Biotechnology Institute & Zernike Institute
for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Valentina Corradi
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Paulo C.T. Souza
- Groningen
Biomolecular Sciences and Biotechnology Institute & Zernike Institute
for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Helgi I. Ingólfsson
- Biosciences
and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, United States
| | - D. Peter Tieleman
- Centre
for Molecular Simulation and Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada
| | - Mark S.P. Sansom
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, U.K.
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21
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Doktorova M, LeVine MV, Khelashvili G, Weinstein H. A New Computational Method for Membrane Compressibility: Bilayer Mechanical Thickness Revisited. Biophys J 2019; 116:487-502. [PMID: 30665693 DOI: 10.1016/j.bpj.2018.12.016] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 11/27/2018] [Accepted: 12/20/2018] [Indexed: 01/24/2023] Open
Abstract
Because lipid bilayers can bend and stretch in ways similar to thin elastic sheets, physical models of bilayer deformation have utilized mechanical constants such as the moduli for bending rigidity (κC) and area compressibility (KA). However, the use of these models to quantify the energetics of membrane deformation associated with protein-membrane interactions, and the membrane response to stress is often hampered by the shortage of experimental data suitable for the estimation of the mechanical constants of various lipid mixtures. Although computational tools such as molecular dynamics simulations can provide alternative means to estimate KA values, current approaches suffer significant technical limitations. Here, we present a novel, to our knowledge, computational framework that allows for a direct estimation of KA values for individual bilayer leaflets. The theory is based on the concept of elasticity and derives KA from real-space analysis of local thickness fluctuations sampled in molecular dynamics simulations. We explore and validate the model on a large set of single and multicomponent bilayers of different lipid compositions and sizes, simulated at different temperatures. The calculated bilayer compressibility moduli agree with values estimated previously from experiments and those obtained from a standard computational method based on a series of constrained tension simulations. We further validate our framework in a comparison with an existing polymer brush model and confirm the polymer brush model's predicted linear relationship with proportionality coefficient of 24, using elastic parameters calculated from the simulation trajectories. The robustness of the results that emerge from the method allows us to revisit the origins of the bilayer mechanical (compressible) thickness and in particular its dependence on acyl-chain unsaturation and the presence of cholesterol.
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Affiliation(s)
- Milka Doktorova
- Tri-Institutional PhD Program in Computational Biology and Medicine, Weill Cornell Medical College, New York, New York.
| | - Michael V LeVine
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, New York; The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Greenberg Center, New York, New York
| | - George Khelashvili
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, New York; The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Greenberg Center, New York, New York
| | - Harel Weinstein
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, New York; The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine, Weill Greenberg Center, New York, New York
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22
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Moradi S, Nowroozi A, Shahlaei M. Shedding light on the structural properties of lipid bilayers using molecular dynamics simulation: a review study. RSC Adv 2019; 9:4644-4658. [PMID: 35520151 PMCID: PMC9060685 DOI: 10.1039/c8ra08441f] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 03/12/2019] [Accepted: 01/16/2019] [Indexed: 12/20/2022] Open
Abstract
This review gives an overview about the some of the most important possible analyzes, technical challenges, and existing protocols that can be performed on the biological membrane by the molecular dynamics simulation.
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Affiliation(s)
- Sajad Moradi
- Nano Drug Delivery Research Center
- Kermanshah University of Medical Sciences
- Kermanshah
- Iran
| | - Amin Nowroozi
- Pharmaceutical Sciences Research Center
- Faculty of Pharmacy
- Kermanshah University of Medical Sciences
- Kermanshah
- Iran
| | - Mohsen Shahlaei
- Medical Biology Research Center
- Kermanshah University of Medical Sciences
- Kermanshah
- Iran
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23
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Mallikarjunaiah KJ, Kinnun JJ, Petrache HI, Brown MF. Flexible lipid nanomaterials studied by NMR spectroscopy. Phys Chem Chem Phys 2019; 21:18422-18457. [DOI: 10.1039/c8cp06179c] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Advances in solid-state nuclear magnetic resonance spectroscopy inform the emergence of material properties from atomistic-level interactions in membrane lipid nanostructures.
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Affiliation(s)
- K. J. Mallikarjunaiah
- Department of Chemistry and Biochemistry
- University of Arizona
- Tucson
- USA
- Department of Physics
| | - Jacob J. Kinnun
- Department of Physics
- Indiana University-Purdue University
- Indianapolis
- USA
| | - Horia I. Petrache
- Department of Physics
- Indiana University-Purdue University
- Indianapolis
- USA
| | - Michael F. Brown
- Department of Chemistry and Biochemistry
- University of Arizona
- Tucson
- USA
- Department of Physics
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24
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Molugu TR, Brown MF. Cholesterol Effects on the Physical Properties of Lipid Membranes Viewed by Solid-state NMR Spectroscopy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1115:99-133. [PMID: 30649757 DOI: 10.1007/978-3-030-04278-3_5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In this chapter, we review the physical properties of lipid/cholesterol mixtures involving studies of model membranes using solid-state NMR spectroscopy. The approach allows one to quantify the average membrane structure, fluctuations, and elastic deformation upon cholesterol interaction. Emphasis is placed on understanding the membrane structural deformation and emergent fluctuations at an atomistic level. Lineshape measurements using solid-state NMR spectroscopy give equilibrium structural properties, while relaxation time measurements study the molecular dynamics over a wide timescale range. The equilibrium properties of glycerophospholipids, sphingolipids, and their binary and tertiary mixtures with cholesterol are accessible. Nonideal mixing of cholesterol with other lipids explains the occurrence of liquid-ordered domains. The entropic loss upon addition of cholesterol to sphingolipids is less than for glycerophospholipids, and may drive formation of lipid rafts. The functional dependence of 2H NMR spin-lattice relaxation (R 1Z) rates on segmental order parameters (S CD) for lipid membranes is indicative of emergent viscoelastic properties. Addition of cholesterol shows stiffening of the bilayer relative to the pure lipids and this effect is diminished for lanosterol. Opposite influences of cholesterol and detergents on collective dynamics and elasticity at an atomistic scale can potentially affect lipid raft formation in cellular membranes.
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Affiliation(s)
- Trivikram R Molugu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ, USA. .,Department of Physics, University of Arizona, Tucson, AZ, USA.
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25
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Al-Ayoubi SR, Schinkel PKF, Berghaus M, Herzog M, Winter R. Combined effects of osmotic and hydrostatic pressure on multilamellar lipid membranes in the presence of PEG and trehalose. SOFT MATTER 2018; 14:8792-8802. [PMID: 30339170 DOI: 10.1039/c8sm01343h] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We studied the interaction of lipid membranes with the disaccharide trehalose (TRH), which is known to stabilize biomembranes against various environmental stress factors. Generally, stress factors include low/high temperature, shear, osmotic and hydrostatic pressure. Small-angle X-ray-scattering was applied in combination with fluorescence spectroscopy and calorimetric measurements to get insights into the influence of trehalose on the supramolecular structure, hydration level, and elastic and thermodynamic properties as well as phase behavior of the model biomembrane DMPC, covering a large region of the temperature, osmotic and hydrostatic pressure phase space. We observed distinct effects of trehalose on the topology of the lipid's supramolecular structure. Trehalose, unlike osmotic pressure induced by polyethylene glycol, leads to a decrease of lamellar order and a swelling of multilamellar vesicles, which is attributable to direct interactions between the membrane and trehalose. Our results revealed a distinct biphasic concentration dependence of the observed effects of trehalose. While trehalose intercalates between the polar head groups at low concentrations, the effects after saturation are dominated by the exclusion of trehalose from the membrane surface.
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Affiliation(s)
- Samy R Al-Ayoubi
- Physical Chemistry I - Biophysical Chemistry, Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn-Str. 4a, 44227 Dortmund, Germany.
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26
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Mukherjee S, Kar RK, Nanga RPR, Mroue KH, Ramamoorthy A, Bhunia A. Accelerated molecular dynamics simulation analysis of MSI-594 in a lipid bilayer. Phys Chem Chem Phys 2018; 19:19289-19299. [PMID: 28702543 DOI: 10.1039/c7cp01941f] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Multidrug resistance against the existing antibiotics is one of the most challenging threats across the globe. Antimicrobial peptides (AMPs), in this regard, are considered to be one of the effective alternatives that can overcome bacterial resistance. MSI-594, a 24-residue linear alpha-helical cationic AMP, has been shown to function via the carpet mechanism to disrupt bacterial membrane systems. To better understand the role of lipid composition in the function of MSI-594, in the present study, eight different model membrane systems have been studied using accelerated molecular dynamics (aMD) simulations. The simulated results are helpful in discriminating the particular effects of cationic MSI-594 against zwitterionic POPC, anionic POPG and POPS, and neutral POPE lipid moieties. Additionally, the effects of various heterogeneous POPC/POPG (7 : 3), POPC/POPS (7 : 3), and POPG/POPE (1 : 3 and 3 : 1) bilayer systems on the dynamic interaction of MSI-594 have also been investigated. The effect on the lipid bilayer due to the interaction with the peptide is characterized by lipid acyl-chain order, membrane thickness, and acyl-chain dynamics. Our simulation results show that the lipid composition affects the membrane interaction of MSI-594, suggesting that membrane selectivity is crucial to its mechanism of action. The results reported in this study are helpful to obtain accurate atomistic-level information governing MSI-594 and its membrane disruptive antimicrobial mechanism of action, and to design next generation potent antimicrobial peptides.
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Affiliation(s)
- Shruti Mukherjee
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VII (M), Kolkata 700 054, India.
| | - Rajiv K Kar
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VII (M), Kolkata 700 054, India.
| | - Ravi Prakash Reddy Nanga
- Biophysics Program and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA. and Department of Radiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kamal H Mroue
- Biophysics Program and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA.
| | - Ayyalusamy Ramamoorthy
- Biophysics Program and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA.
| | - Anirban Bhunia
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VII (M), Kolkata 700 054, India.
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27
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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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28
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Ivica J, Williamson PTF, de Planque MRR. Salt Gradient Modulation of MicroRNA Translocation through a Biological Nanopore. Anal Chem 2017; 89:8822-8829. [DOI: 10.1021/acs.analchem.7b01246] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Josip Ivica
- Electronics
and Computer Science, ‡Centre for Biological Sciences, and §Institute for
Life Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Philip T. F. Williamson
- Electronics
and Computer Science, ‡Centre for Biological Sciences, and §Institute for
Life Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom
| | - Maurits R. R. de Planque
- Electronics
and Computer Science, ‡Centre for Biological Sciences, and §Institute for
Life Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom
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29
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Affiliation(s)
- Michael F. Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona 85721
- Department of Physics, University of Arizona, Tucson, Arizona 85721
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30
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Bera I, Klauda JB. Molecular Simulations of Mixed Lipid Bilayers with Sphingomyelin, Glycerophospholipids, and Cholesterol. J Phys Chem B 2017; 121:5197-5208. [DOI: 10.1021/acs.jpcb.7b00359] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Indrani Bera
- Department
of Chemical and Biomolecular Engineering and ‡Biophysics Program, University of Maryland, College Park, Maryland 20742, United States
| | - Jeffery B. Klauda
- Department
of Chemical and Biomolecular Engineering and ‡Biophysics Program, University of Maryland, College Park, Maryland 20742, United States
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31
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Measurement of the bending elastic modulus in unilamellar vesicles membranes by fast field cycling NMR relaxometry. Chem Phys Lipids 2016; 201:21-27. [DOI: 10.1016/j.chemphyslip.2016.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 09/22/2016] [Accepted: 10/31/2016] [Indexed: 01/01/2023]
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32
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Polo A, Guariniello S, Colonna G, Ciliberto G, Costantini S. A study on the structural features of SELK, an over-expressed protein in hepatocellular carcinoma, by molecular dynamics simulations in a lipid-water system. MOLECULAR BIOSYSTEMS 2016; 12:3209-22. [PMID: 27524292 DOI: 10.1039/c6mb00469e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Human SELK is a small trans-membrane selenoprotein characterized by a single trans-membrane helix, while the N-terminal region protrudes into the lumen and the long C-terminal domain into the cytoplasm. SELK is over-expressed in some cancers, like hepatocellular carcinoma; however its precise role in cancer development is presently unknown. SELK is involved in promoting the calcium flux, catalyzing palmitoylation reactions and protein degradation in the endoplasmic reticulum (ER). Therefore, this protein should bind many different proteins like p97/VCP in the supramolecular complex involved in the ER degradation pathway. To study the structural features of SELK in the membrane, we have modeled the protein and then subjected it to molecular dynamics simulations in a lipid-water system. The model shows a N-terminal domain with three β-strands and a short helix, a well-defined trans-membrane helix and a C-terminal domain that lacks a persistent secondary structure and contains long disordered regions. The trajectory analysis during the simulation evidences that: (i) the N-terminal region explores a limited conformational space and is stabilized by intra-peptide H-bonds as well with membrane lipids and water, (ii) the trans-membrane helix was found to be quite stable and (iii) the disordered C-terminal region is stabilized by H-bonds with clustered water molecules as well as by rapidly interchanging intra-peptidic H-bonds, with a structural tendency to compact around the four HUB residues found for this domain. Moreover, N-terminal and C-terminal clusters are distributed differently in the conformational space suggesting that their dynamics are coupled complicatedly through the membrane. Further analyses have shown that the N-terminal has a tendency to pivot around the insertion with the TM-helix through the fluctuations of the three β-strands, which, in turn, show features similar to WW-domains. These results will be useful to study the SELK, SELS and VCP complex representing an interesting druggable target for cancer.
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Affiliation(s)
- Andrea Polo
- Servizio di Informatica Medica, Azienda Ospedaliera Universitaria, Seconda Università di Napoli, Napoli, Italy
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33
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Abstract
Sick excitable cells (ie, Nav channel-expressing cells injured by trauma, ischemia, inflammatory, and other conditions) typically exhibit "acquired sodium channelopathies" which, we argue, reflect bleb-damaged membranes rendering their Nav channels "leaky." The situation is excitotoxic because untreated Nav leak exacerbates bleb damage. Fast Nav inactivation (a voltage-independent process) is so tightly coupled, kinetically speaking, to the inherently voltage-dependent process of fast activation that when bleb damage accelerates and thus left-shifts macroscopic fast activation, fast inactivation accelerates to the same extent. The coupled g(V) and availability(V) processes and their window conductance regions consequently left-shift by the same number of millivolts. These damage-induced hyperpolarizing shifts, whose magnitude increases with damage intensity, are called coupled left shift (CLS). Based on past work and modeling, we discuss how to test for Nav-CLS, emphasizing the virtue of sawtooth ramp clamp. We explain that it is the inherent mechanosensitivity of Nav activation that underlies Nav-CLS. Using modeling of excitability, we show the known process of Nav-CLS is sufficient to predict a wide variety of "sick excitable cell" phenomena, from hyperexcitability through to depolarizing block. When living cells are mimicked by inclusion of pumps, mild Nav-CLS produces a wide array of burst phenomena and subthreshold oscillations. Dynamical analysis of mild damage scenarios shows how these phenomena reflect changes in spike thresholds as the pumps try to counteract the leaky Nav channels. Smart Nav inhibitors designed for sick excitable cells would target bleb-damaged membrane, buying time for cell-mediated removal or repair of Nav-bearing membrane that has become bleb-damaged (ie, detached from the cytoskeleton).
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Affiliation(s)
- C E Morris
- Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - B Joos
- University of Ottawa, Ottawa, ON, Canada
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34
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Mendes Ferreira T, Sood R, Bärenwald R, Carlström G, Topgaard D, Saalwächter K, Kinnunen PKJ, Ollila OHS. Acyl Chain Disorder and Azelaoyl Orientation in Lipid Membranes Containing Oxidized Lipids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:6524-33. [PMID: 27260273 DOI: 10.1021/acs.langmuir.6b00788] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Oxidized phospholipids occur naturally in conditions of oxidative stress and have been suggested to play an important role in a number of pathological conditions due to their effects on a lipid membrane acyl chain orientation, ordering, and permeability. Here we investigate the effect of the oxidized phospholipid 1-palmitoyl-2-azelaoyl-sn-glycero-3-phosphocholine (PazePC) on a model membrane of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) using a combination of (13)C-(1)H dipolar-recoupling nuclear magnetic resonance (NMR) experiments and united-atom molecular dynamics (MD) simulations. The obtained experimental order parameter SCH profiles show that the presence of 30 mol % PazePC in the bilayer significantly increases the gauche content of the POPC acyl chains, therefore decreasing the thickness of the bilayer, although with no stable bilayer pore formation. The MD simulations reproduce the disordering effect and indicate that the orientation of the azelaoyl chain is highly dependent on its protonation state with acyl chain reversal for fully deprotonated states and a parallel orientation along the interfacial plane for fully protonated states, deprotonated and protonated azelaoyl chains having negative and positive SCH profiles, respectively. Only fully or nearly fully protonated azelaoyl chain are observed in the (13)C-(1)H dipolar-recoupling NMR experiments. The experiments show positive SCH values for the azelaoyl segments confirming for the first time that oxidized chains with polar termini adopt a parallel orientation to the bilayer plane as predicted in MD simulations.
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Affiliation(s)
- Tiago Mendes Ferreira
- Institut für Physik - NMR, Martin-Luther-Universität Halle-Wittenberg , 06108 Halle, Germany
| | - Rohit Sood
- Department of Neuroscience and Biomedical Engineering, Aalto University , 02150 Espoo, Finland
| | - Ruth Bärenwald
- Institut für Physik - NMR, Martin-Luther-Universität Halle-Wittenberg , 06108 Halle, Germany
| | - Göran Carlström
- Centre for Analysis and Synthesis, Lund University , SE-221 00 Lund, Sweden
| | - Daniel Topgaard
- Physical Chemistry, Lund University , SE-221 00 Lund, Sweden
| | - Kay Saalwächter
- Institut für Physik - NMR, Martin-Luther-Universität Halle-Wittenberg , 06108 Halle, Germany
| | - Paavo K J Kinnunen
- Department of Neuroscience and Biomedical Engineering, Aalto University , 02150 Espoo, Finland
| | - O H Samuli Ollila
- Department of Neuroscience and Biomedical Engineering, Aalto University , 02150 Espoo, Finland
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35
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Molugu TR, Brown MF. Cholesterol-induced suppression of membrane elastic fluctuations at the atomistic level. Chem Phys Lipids 2016; 199:39-51. [PMID: 27154600 DOI: 10.1016/j.chemphyslip.2016.05.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 04/29/2016] [Accepted: 05/02/2016] [Indexed: 12/14/2022]
Abstract
Applications of solid-state NMR spectroscopy for investigating the influences of lipid-cholesterol interactions on membrane fluctuations are reviewed in this paper. Emphasis is placed on understanding the energy landscapes and fluctuations at an emergent atomistic level. Solid-state (2)H NMR spectroscopy directly measures residual quadrupolar couplings (RQCs) due to individual C-(2)H labeled segments of the lipid molecules. Moreover, residual dipolar couplings (RDCs) of (13)C-(1)H bonds are obtained in separated local-field NMR spectroscopy. The distributions of RQC or RDC values give nearly complete profiles of the order parameters as a function of acyl segment position. Measured equilibrium properties of glycerophospholipids and sphingolipids including their binary and tertiary mixtures with cholesterol show unequal mixing associated with liquid-ordered domains. The entropic loss upon addition of cholesterol to sphingolipids is less than for glycerophospholipids and may drive the formation of lipid rafts. In addition relaxation time measurements enable one to study the molecular dynamics over a wide time-scale range. For (2)H NMR the experimental spin-lattice (R1Z) relaxation rates follow a theoretical square-law dependence on segmental order parameters (SCD) due to collective slow dynamics over mesoscopic length scales. The functional dependence for the liquid-crystalline lipid membranes is indicative of viscoelastic properties as they emerge from atomistic-level interactions. A striking decrease in square-law slope upon addition of cholesterol denotes stiffening relative to the pure lipid bilayers that is diminished in the case of lanosterol. Measured equilibrium properties and relaxation rates infer opposite influences of cholesterol and detergents on collective dynamics and elasticity at an atomistic scale that potentially affects lipid raft formation in cellular membranes.
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Affiliation(s)
- Trivikram R Molugu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA; Department of Physics, University of Arizona, Tucson, AZ 85721, USA.
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36
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Zhu T, Jiang Z, Ma Y, Hu Y. Preservation of Supported Lipid Membrane Integrity from Thermal Disruption: Osmotic Effect. ACS APPLIED MATERIALS & INTERFACES 2016; 8:5857-5866. [PMID: 26886864 DOI: 10.1021/acsami.5b12153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Preservation of structural integrity under various environmental conditions is one major concern in the development of the supported lipid membrane (SLM)-based devices. It is common for SLMs to experience temperature shifts from manufacture, processing, storage, and transport to operation. In this work, we studied the thermal adaption of the supported membranes on silica substrates. Homogenous SLMs with little defects were formed through the vesicle fusion method. The mass and fluidity of the bilayers were found to deteriorate from a heating process but not a cooling process. Fluorescence characterizations showed that the membranes initially budded as a result of heating-induced lipid lateral area expansion, followed by the possible fates including maintenance, retraction, and fission, among which the last contributes to the irreversible compromise of the SLM integrity and spontaneous release of the interlipid stress accumulated. Based on the mechanism, we developed a strategy to protect SLMs from thermal disruption by increasing the solute concentration in medium. An improved preservation of the membrane mass and fluidity against the heating process was observed, accompanied by a decrease in the retraction and fission of the buds. Theoretical analysis revealed a high osmotic energy penalty for the fission, which accounts for the depressed disruption. This osmotic-based protection strategy is facile, solute nonspecific, and long-term efficient and has little impact on the original SLM properties. The results may help broaden SLM applications and sustain the robustness of SLM-based devices under multiple thermal conditions.
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Affiliation(s)
- Tao Zhu
- Collaborative Innovation Center of Advanced Microstructures and Department of Physics, Nanjing University , Nanjing 210093, China
| | - Zhongying Jiang
- School of Electronics and Information Engineering, Yi Li Normal University , Yining 835000, China
- Laboratory of Solid State Microstructures, Nanjing University , Nanjing 210093, China
| | - Yuqiang Ma
- Collaborative Innovation Center of Advanced Microstructures and Department of Physics, Nanjing University , Nanjing 210093, China
- Center for Soft Condensed Matter Physics and Interdisciplinary Research, Soochow University , Suzhou 215006, China
| | - Yong Hu
- College of Engineering and Applied Sciences, Nanjing University , Nanjing 210093, China
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37
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Kocer A. Mechanisms of mechanosensing - mechanosensitive channels, function and re-engineering. Curr Opin Chem Biol 2015; 29:120-7. [PMID: 26610201 DOI: 10.1016/j.cbpa.2015.10.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 09/30/2015] [Accepted: 10/06/2015] [Indexed: 10/22/2022]
Abstract
Sensing and responding to mechanical stimuli is an ancient behavior and ubiquitous to all forms of life. One of its players 'mechanosensitive ion channels' are involved in processes from osmosensing in bacteria to pain in humans. However, the mechanism of mechanosensing is yet to be elucidated. This review describes recent developments in the understanding of a bacterial mechanosensitive channel. Force from the lipid principle of mechanosensation, new methods to understand protein-lipid interactions, the role of water in the gating, the use of engineered mechanosensitive channels in the understanding of the gating mechanism and application of the accumulated knowledge in the field of drug delivery, drug design and sensor technologies are discussed.
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Affiliation(s)
- Armagan Kocer
- University of Groningen, University Medical Center Groningen, Ant. Deusinglaan 1, 9713 AV Groningen, The Netherlands.
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38
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Leftin A, Molugu TR, Job C, Beyer K, Brown MF. Area per lipid and cholesterol interactions in membranes from separated local-field (13)C NMR spectroscopy. Biophys J 2015; 107:2274-86. [PMID: 25418296 DOI: 10.1016/j.bpj.2014.07.044] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 06/24/2014] [Accepted: 07/15/2014] [Indexed: 10/24/2022] Open
Abstract
Investigations of lipid membranes using NMR spectroscopy generally require isotopic labeling, often precluding structural studies of complex lipid systems. Solid-state (13)C magic-angle spinning NMR spectroscopy at natural isotopic abundance gives site-specific structural information that can aid in the characterization of complex biomembranes. Using the separated local-field experiment DROSS, we resolved (13)C-(1)H residual dipolar couplings that were interpreted with a statistical mean-torque model. Liquid-disordered and liquid-ordered phases were characterized according to membrane thickness and average cross-sectional area per lipid. Knowledge of such structural parameters is vital for molecular dynamics simulations, and provides information about the balance of forces in membrane lipid bilayers. Experiments were conducted with both phosphatidylcholine (dimyristoylphosphatidylcholine (DMPC) and palmitoyloleoylphosphatidylcholine (POPC)) and egg-yolk sphingomyelin (EYSM) lipids, and allowed us to extract segmental order parameters from the (13)C-(1)H residual dipolar couplings. Order parameters were used to calculate membrane structural quantities, including the area per lipid and bilayer thickness. Relative to POPC, EYSM is more ordered in the ld phase and experiences less structural perturbation upon adding 50% cholesterol to form the lo phase. The loss of configurational entropy is smaller for EYSM than for POPC, thus favoring its interaction with cholesterol in raftlike lipid systems. Our studies show that solid-state (13)C NMR spectroscopy is applicable to investigations of complex lipids and makes it possible to obtain structural parameters for biomembrane systems where isotope labeling may be prohibitive.
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Affiliation(s)
- Avigdor Leftin
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Trivikram R Molugu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Constantin Job
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Klaus Beyer
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona; Department of Physics, University of Arizona, Tucson, Arizona.
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