1
|
Schlaich A, Daldrop JO, Kowalik B, Kanduč M, Schneck E, Netz RR. Water Structuring Induces Nonuniversal Hydration Repulsion between Polar Surfaces: Quantitative Comparison between Molecular Simulations, Theory, and Experiments. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:7896-7906. [PMID: 38578930 PMCID: PMC11025125 DOI: 10.1021/acs.langmuir.3c03656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 03/13/2024] [Accepted: 03/15/2024] [Indexed: 04/07/2024]
Abstract
Polar surfaces in water typically repel each other at close separations, even if they are charge-neutral. This so-called hydration repulsion balances the van der Waals attraction and gives rise to a stable nanometric water layer between the polar surfaces. The resulting hydration water layer is crucial for the properties of concentrated suspensions of lipid membranes and hydrophilic particles in biology and technology, but its origin is unclear. It has been suggested that surface-induced molecular water structuring is responsible for the hydration repulsion, but a quantitative proof of this water-structuring hypothesis is missing. To gain an understanding of the mechanism causing hydration repulsion, we perform molecular simulations of different planar polar surfaces in water. Our simulated hydration forces between phospholipid bilayers agree perfectly with experiments, validating the simulation model and methods. For the comparison with theory, it is important to split the simulated total surface interaction force into a direct contribution from surface-surface molecular interactions and an indirect water-mediated contribution. We find the indirect hydration force and the structural water-ordering profiles from the simulations to be in perfect agreement with the predictions from theoretical models that account for the surface-induced water ordering, which strongly supports the water-structuring hypothesis for the hydration force. However, the comparison between the simulations for polar surfaces with different headgroup architectures reveals significantly different decay lengths of the indirect water-mediated hydration-force, which for laterally homogeneous water structuring would imply different bulk-water properties. We conclude that laterally inhomogeneous water ordering, induced by laterally inhomogeneous surface structures, shapes the hydration repulsion between polar surfaces in a decisive manner. Thus, the indirect water-mediated part of the hydration repulsion is caused by surface-induced water structuring but is surface-specific and thus nonuniversal.
Collapse
Affiliation(s)
- Alexander Schlaich
- Stuttgart
Center for Simulation Science (SC SimTech), University of Stuttgart, 70569 Stuttgart, Germany
- Institute
for Computational Physics, University of
Stuttgart, 70569 Stuttgart, Germany
| | - Jan O. Daldrop
- Fachbereich
Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Bartosz Kowalik
- Fachbereich
Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Matej Kanduč
- Department
of Theoretical Physics, Jožef Stefan
Institute, SI-1000 Ljubljana, Slovenia
| | - Emanuel Schneck
- Institut
für Physik Kondensierter Materie, Technische Universität Darmstadt, Hochschulstrasse 8, Darmstadt 64289, Germany
| | - Roland R. Netz
- Fachbereich
Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| |
Collapse
|
2
|
Kanduč M, Schneck E, Netz RR. Understanding the "Berg limit": the 65° contact angle as the universal adhesion threshold of biomatter. Phys Chem Chem Phys 2024; 26:713-723. [PMID: 38100091 DOI: 10.1039/d3cp05084j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Surface phenomena in aqueous environments such as long-range hydrophobic attraction, macromolecular adhesion, and even biofouling are predominantly influenced by a fundamental parameter-the water contact angle. The minimal contact angle required for these and related phenomena to occur has been repeatedly reported to be around 65° and is commonly referred to as the "Berg limit." However, the universality of this specific threshold across diverse contexts has remained puzzling. In this perspective article, we aim to rationalize the reoccurrence of this enigmatic contact angle. We show that the relevant scenarios can be effectively conceptualized as three-phase problems involving the surface of interest, water, and a generic oil-like material that is representative of the nonpolar constituents within interacting entities. Our analysis reveals that attraction and adhesion emerge when substrates display an underwater oleophilic character, corresponding to a "hydrophobicity under oil", which occurs for contact angles above approximately 65°. This streamlined view provides valuable insights into macromolecular interactions and holds implications for technological applications.
Collapse
Affiliation(s)
- Matej Kanduč
- Department of Theoretical Physics, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
| | - Emanuel Schneck
- Department of Physics, Technische Universität Darmstadt, Hochschulstrasse 8, Darmstadt 64289, Germany
| | - Roland R Netz
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany
| |
Collapse
|
3
|
Shi W, Cai Y, Zhu H, Peng H, Voyer J, Rits-Volloch S, Cao H, Mayer ML, Song K, Xu C, Lu J, Zhang J, Chen B. Cryo-EM structure of SARS-CoV-2 postfusion spike in membrane. Nature 2023; 619:403-409. [PMID: 37285872 DOI: 10.1038/s41586-023-06273-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Accepted: 05/31/2023] [Indexed: 06/09/2023]
Abstract
The entry of SARS-CoV-2 into host cells depends on the refolding of the virus-encoded spike protein from a prefusion conformation, which is metastable after cleavage, to a lower-energy stable postfusion conformation1,2. This transition overcomes kinetic barriers for fusion of viral and target cell membranes3,4. Here we report a cryogenic electron microscopy (cryo-EM) structure of the intact postfusion spike in a lipid bilayer that represents the single-membrane product of the fusion reaction. The structure provides structural definition of the functionally critical membrane-interacting segments, including the fusion peptide and transmembrane anchor. The internal fusion peptide forms a hairpin-like wedge that spans almost the entire lipid bilayer and the transmembrane segment wraps around the fusion peptide at the last stage of membrane fusion. These results advance our understanding of the spike protein in a membrane environment and may guide development of intervention strategies.
Collapse
Affiliation(s)
- Wei Shi
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA
| | - Yongfei Cai
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA
- CSL Seqirus, Waltham, MA, USA
| | - Haisun Zhu
- Institute for Protein Innovation, Harvard Institutes of Medicine, Boston, MA, USA
| | - Hanqin Peng
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | - Jewel Voyer
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA, USA
| | | | - Hong Cao
- Codex BioSolutions, Rockville, MD, USA
| | - Megan L Mayer
- The Harvard Cryo-EM Center for Structural Biology, Boston, MA, USA
| | - Kangkang Song
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
- Cryo-EM Core Facility, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Chen Xu
- Department of Biochemistry & Molecular Biotechnology, University of Massachusetts Chan Medical School, Worcester, MA, USA
- Cryo-EM Core Facility, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Jianming Lu
- Codex BioSolutions, Rockville, MD, USA
- Department of Biochemistry and Molecular and Cellular Biology, Georgetown University, Washington, DC, USA
| | - Jun Zhang
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA.
| | - Bing Chen
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA, USA.
- Department of Pediatrics, Harvard Medical School, Boston, MA, USA.
| |
Collapse
|
4
|
Incorporation and localisation of alkanes in a protomembrane model by neutron diffraction. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184119. [PMID: 36638951 DOI: 10.1016/j.bbamem.2023.184119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/15/2022] [Accepted: 01/03/2023] [Indexed: 01/11/2023]
Abstract
Protomembranes at the origin of life were likely composed of short-chain lipids, readily available on the early Earth. Membranes formed by such lipids are less stable and more permeable under extreme conditions, so a novel membrane architecture was suggested to validate the accuracy of this assumption. The model membrane includes the presence of a layer of alkanes in the mid-plane of the protomembrane in between the two monolayer leaflets and lying perpendicular to the lipid acyl chains. Here, we investigated such a possibility experimentally for membranes formed by the short-chain phospholipid 1,2-didecanoyl-sn-glycero-3-phophocholine, including or not the alkanes eicosane, squalane or triacontane by means of neutron membrane diffraction and contrast variation. We found strong indications for incorporation of two of the three alkanes in the membrane mid-plane through the determination of neutron scattering length density profiles with hydrogenated vs deuterated alkanes and membrane swelling at various relative humidities indicating a slightly increased bilayer thickness when the alkanes are incorporated into the bilayers. The selectivity of the incorporation points out the role of the length of the n-alkanes with respect to the capacity of the membrane to incorporate them.
Collapse
|
5
|
Quagliarini E, Wang J, Renzi S, Cui L, Digiacomo L, Ferri G, Pesce L, De Lorenzi V, Matteoli G, Amenitsch H, Masuelli L, Bei R, Pozzi D, Amici A, Cardarelli F, Marchini C, Caracciolo G. Mechanistic Insights into the Superior DNA Delivery Efficiency of Multicomponent Lipid Nanoparticles: An In Vitro and In Vivo Study. ACS APPLIED MATERIALS & INTERFACES 2022; 14:56666-56677. [PMID: 36524967 DOI: 10.1021/acsami.2c20019] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Lipid nanoparticles (LNPs) are currently having an increasing impact on nanomedicines as delivery agents, among others, of RNA molecules (e.g., short interfering RNA for the treatment of hereditary diseases or messenger RNA for the development of COVID-19 vaccines). Despite this, the delivery of plasmid DNA (pDNA) by LNPs in preclinical studies is still unsatisfactory, mainly due to the lack of systematic structural and functional studies on DNA-loaded LNPs. To tackle this issue, we developed, characterized, and tested a library of 16 multicomponent DNA-loaded LNPs which were prepared by microfluidics and differed in lipid composition, surface functionalization, and manufacturing factors. 8 out of 16 formulations exhibited proper size and zeta potential and passed to the validation step, that is, the simultaneous quantification of transfection efficiency and cell viability in human embryonic kidney cells (HEK-293). The most efficient formulation (LNP15) was then successfully validated both in vitro, in an immortalized adult keratinocyte cell line (HaCaT) and in an epidermoid cervical cancer cell line (CaSki), and in vivo as a nanocarrier to deliver a cancer vaccine against the benchmark target tyrosine-kinase receptor HER2 in C57BL/6 mice. Finally, by a combination of confocal microscopy, transmission electron microscopy and synchrotron small-angle X-ray scattering, we were able to show that the superior efficiency of LNP15 can be linked to its disordered nanostructure consisting of small-size unoriented layers of pDNA sandwiched between closely apposed lipid membranes that undergo massive destabilization upon interaction with cellular lipids. Our results provide new insights into the structure-activity relationship of pDNA-loaded LNPs and pave the way to the clinical translation of this gene delivery technology.
Collapse
Affiliation(s)
- Erica Quagliarini
- NanoDelivery Lab, Department of Molecular Medicine, Sapienza University of Rome, 00161Rome, Italy
| | - Junbiao Wang
- School of Biosciences and Veterinary Medicine, University of Camerino, 62032Camerino, Italy
| | - Serena Renzi
- NanoDelivery Lab, Department of Molecular Medicine, Sapienza University of Rome, 00161Rome, Italy
| | - Lishan Cui
- School of Biosciences and Veterinary Medicine, University of Camerino, 62032Camerino, Italy
| | - Luca Digiacomo
- NanoDelivery Lab, Department of Molecular Medicine, Sapienza University of Rome, 00161Rome, Italy
| | - Gianmarco Ferri
- Laboratorio NEST, Scuola Normale Superiore, Piazza San Silvestro 12, 56127Pisa, Italy
| | - Luca Pesce
- Laboratorio NEST, Scuola Normale Superiore, Piazza San Silvestro 12, 56127Pisa, Italy
| | - Valentina De Lorenzi
- Laboratorio NEST, Scuola Normale Superiore, Piazza San Silvestro 12, 56127Pisa, Italy
| | - Giulia Matteoli
- Laboratorio NEST, Scuola Normale Superiore, Piazza San Silvestro 12, 56127Pisa, Italy
| | - Heinz Amenitsch
- Institute of Inorganic Chemistry, Graz University of Technology, 8010Graz, Austria
| | - Laura Masuelli
- Department of Experimental Medicine, University of Rome "Sapienza", 00161Rome, Italy
| | - Roberto Bei
- Department of Clinical Sciences and Translational Medicine, University of Rome "Tor Vergata", 00133Rome, Italy
| | - Daniela Pozzi
- NanoDelivery Lab, Department of Molecular Medicine, Sapienza University of Rome, 00161Rome, Italy
| | - Augusto Amici
- School of Biosciences and Veterinary Medicine, University of Camerino, 62032Camerino, Italy
| | - Francesco Cardarelli
- Laboratorio NEST, Scuola Normale Superiore, Piazza San Silvestro 12, 56127Pisa, Italy
| | - Cristina Marchini
- School of Biosciences and Veterinary Medicine, University of Camerino, 62032Camerino, Italy
| | - Giulio Caracciolo
- NanoDelivery Lab, Department of Molecular Medicine, Sapienza University of Rome, 00161Rome, Italy
| |
Collapse
|
6
|
Shi W, Cai Y, Zhu H, Peng H, Voyer J, Rits-Volloch S, Cao H, Mayer ML, Song K, Xu C, Lu J, Zhang J, Chen B. Cryo-EM structure of SARS-CoV-2 postfusion spike in membrane. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2022:2022.12.05.519151. [PMID: 36523411 PMCID: PMC9753783 DOI: 10.1101/2022.12.05.519151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) into host cells depends on refolding of the virus-encoded spike protein from a prefusion conformation, metastable after cleavage, to a lower energy, stable postfusion conformation. This transition overcomes kinetic barriers for fusion of viral and target cell membranes. We report here a cryo-EM structure of the intact postfusion spike in a lipid bilayer that represents single-membrane product of the fusion reaction. The structure provides structural definition of the functionally critical membraneinteracting segments, including the fusion peptide and transmembrane anchor. The internal fusion peptide forms a hairpin-like wedge that spans almost the entire lipid bilayer and the transmembrane segment wraps around the fusion peptide at the last stage of membrane fusion. These results advance our understanding of the spike protein in a membrane environment and may guide development of intervention strategies.
Collapse
|
7
|
Siyar M, Lashkarbolooki M. Evaluation of the interfacial tension of binary surfactant mixtures and crude oil using the response surface method. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.120253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
|
8
|
Bessif B, Pfohl T, Heck B, Alshetwi Y, Khechine E, Xu J, Reiter G. In Situ Dissolution and Swelling of Confined Lamellar Polymer Crystals through Exposure to Humid Air. Macromolecules 2022. [DOI: 10.1021/acs.macromol.2c00496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Brahim Bessif
- Physikalisches Institut, Albert-Ludwigs-Universität, 79104 Freiburg, Germany
| | - Thomas Pfohl
- Physikalisches Institut, Albert-Ludwigs-Universität, 79104 Freiburg, Germany
| | - Barbara Heck
- Physikalisches Institut, Albert-Ludwigs-Universität, 79104 Freiburg, Germany
| | - Yaser Alshetwi
- Physikalisches Institut, Albert-Ludwigs-Universität, 79104 Freiburg, Germany
| | - Emna Khechine
- Physikalisches Institut, Albert-Ludwigs-Universität, 79104 Freiburg, Germany
| | - Jun Xu
- Institute of Polymer Science and Engineering, Department of Chemical Engineering, Tsinghua University, 100084 Beijing, China
| | - Günter Reiter
- Physikalisches Institut, Albert-Ludwigs-Universität, 79104 Freiburg, Germany
| |
Collapse
|
9
|
Walker-Gibbons R, Kubincová A, Hünenberger PH, Krishnan M. The Role of Surface Chemistry in the Orientational Behavior of Water at an Interface. J Phys Chem B 2022; 126:4697-4710. [PMID: 35726865 PMCID: PMC9251758 DOI: 10.1021/acs.jpcb.2c01752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2022] [Revised: 05/18/2022] [Indexed: 11/30/2022]
Abstract
Molecular dynamics studies have demonstrated that molecular water at an interface, with either a gas or a solid, displays anisotropic orientational behavior in contrast to its bulk counterpart. This effect has been recently implicated in the like-charge attraction problem for colloidal particles in solution. Here, negatively charged particles in solution display a long-ranged attraction where continuum electrostatic theory predicts monotonically repulsive interactions, particularly in solutions with monovalent salt ions at low ionic strength. Anisotropic orientational behavior of solvent molecules at an interface gives rise to an excess interfacial electrical potential which we suggest generates an additional solvation contribution to the total free energy that is traditionally overlooked in continuum descriptions of interparticle interactions in solution. In the present investigation we perform molecular dynamics simulation based calculations of the interfacial potential using realistic surface models representing various chemistries as well as different solvents. Similar to previous work that focused on simple model surfaces constructed by using oxygen atoms, we find that solvents at more realistic model surfaces exhibit substantial anisotropic orientational behavior. We explore the dependence of the interfacial solvation potential on surface properties such as surface group chemistry and group density at silica and carboxylated polystyrene interfaces. For water, we note surprisingly good agreement between results obtained for a simple O-atom wall and more complex surface models, suggesting a general qualitative consistency of the interfacial solvation effect for surfaces in contact with water. In contrast, for an aprotic solvent such as DMSO, surface chemistry appears to exert a stronger influence on the sign and magnitude of the interfacial solvation potential. The study carries broad implications for molecular-scale interactions and may find relevance in explaining a range of phenomena in soft-matter physics and cell biology.
Collapse
Affiliation(s)
- Rowan Walker-Gibbons
- Physical
& Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Alžbeta Kubincová
- Laboratory
of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Philippe H. Hünenberger
- Laboratory
of Physical Chemistry, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland
| | - Madhavi Krishnan
- Physical
& Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| |
Collapse
|
10
|
Kazaryan PS, Gallyamov MO, Kondratenko MS. Study of the Droplet Pinning Force in the Transition from Dry to Liquid-Infused Thin Polymer Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:1114-1123. [PMID: 35015553 DOI: 10.1021/acs.langmuir.1c02767] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The change in the pinning force during the transition from dry to oil-impregnated thin polymer films is studied for droplets of water and hexadecane. A careful variation of the oil amount in the films is performed by means of supercritical impregnation. The film thickness dependence on the oil content is measured using ellipsometry and compared to gel swelling theory estimates. Depending on the oil content, two cases of pinning force behavior have been identified. For each case, the factors that determine the pinning force are discussed. The pinning force in the transition from dry to equilibrium swollen gel films is well approximated by the Joanny and de Gennes hysteresis model of dilute defects.
Collapse
Affiliation(s)
- Polina S Kazaryan
- Faculty of Physics, M. V. Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
| | - Marat O Gallyamov
- Faculty of Physics, M. V. Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
- A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova 28, Moscow 119991, Russian Federation
| | - Mikhail S Kondratenko
- Faculty of Physics, M. V. Lomonosov Moscow State University, Leninskie Gory 1-2, Moscow 119991, Russian Federation
| |
Collapse
|
11
|
Behjatian A, Walker-Gibbons R, Schekochihin AA, Krishnan M. Nonmonotonic Pair Potentials in the Interaction of Like-Charged Objects in Solution. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:786-800. [PMID: 34981941 DOI: 10.1021/acs.langmuir.1c02801] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We consider the long-standing like-charge attraction problem, wherein under certain conditions, similarly charged spheres suspended in aqueous electrolyte have been observed to display a minimum in their interaction potential, contrary to the intuitively expected monotonically varying repulsion. Recently, we described an interfacial mechanism invoking the molecular nature of the solvent that explains this anomalous experimental observation. In our model for the interaction of negatively charged particles in water, the minimum in the pair potential results from the superposition of competing contributions to the total free energy. One of these contributions is the canonical repulsive electrostatic term, whereas the other is a solvation-induced attractive contribution. We find that whereas both contributions grow approximately exponentially with decreasing interparticle separation, the occurrence of a stable, long-ranged minimum in the pair potential arises from differences in the precise interparticle separation dependence of the two terms. Specifically, the interfacial solvation term exhibits a more gradual decay with distance than the electrostatic repulsion, permitting the attractive contribution to dominate the interaction at large distances. Importantly, these disparities become evident in quantities calculated from exact numerical solutions to the governing nonlinear Poisson-Boltzmann (PB) equation for the spatial electrical potential distribution in the system. In marked contrast, we find that the linearized PB equation, applicable in the regime of low surface electrical potentials, does not support nonmonotonic trends in the total interaction free energy within the present model. Our results point to the importance of exact descriptions of electrostatic interactions in real systems that most often do not subscribe to particular mathematical limits where analytical approximations may provide a sufficiently accurate description of the problem.
Collapse
Affiliation(s)
- Ali Behjatian
- Physical & Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Rowan Walker-Gibbons
- Physical & Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
| | - Alexander A Schekochihin
- Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom
- Merton College, Merton Street, Oxford OX1 4JD, United Kingdom
| | - Madhavi Krishnan
- Physical & Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom
- Merton College, Merton Street, Oxford OX1 4JD, United Kingdom
| |
Collapse
|
12
|
Yang L. Scattering measurements on lipid membrane structures. Methods Enzymol 2022; 677:385-415. [DOI: 10.1016/bs.mie.2022.08.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
13
|
Viral Membrane Fusion Proteins and RNA Sorting Mechanisms for the Molecular Delivery by Exosomes. Cells 2021; 10:cells10113043. [PMID: 34831268 PMCID: PMC8622164 DOI: 10.3390/cells10113043] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 10/29/2021] [Accepted: 11/02/2021] [Indexed: 11/21/2022] Open
Abstract
The advancement of precision medicine critically depends on the robustness and specificity of the carriers used for the targeted delivery of effector molecules in the human body. Numerous nanocarriers have been explored in vivo, to ensure the precise delivery of molecular cargos via tissue-specific targeting, including the endocrine part of the pancreas, thyroid, and adrenal glands. However, even after reaching the target organ, the cargo-carrying vehicle needs to enter the cell and then escape lysosomal destruction. Most artificial nanocarriers suffer from intrinsic limitations that prevent them from completing the specific delivery of the cargo. In this respect, extracellular vesicles (EVs) seem to be the natural tool for payload delivery due to their versatility and low toxicity. However, EV-mediated delivery is not selective and is usually short-ranged. By inserting the viral membrane fusion proteins into exosomes, it is possible to increase the efficiency of membrane recognition and also ease the process of membrane fusion. This review describes the molecular details of the viral-assisted interaction between the target cell and EVs. We also discuss the question of the usability of viral fusion proteins in developing extracellular vesicle-based nanocarriers with a higher efficacy of payload delivery. Finally, this review specifically highlights the role of Gag and RNA binding proteins in RNA sorting into EVs.
Collapse
|
14
|
Shoaib M, Molaei N, Bobicki ER. Physical aging in aqueous nematic gels of a swelling nanoclay: sol (phase) to gel (state) transition. Phys Chem Chem Phys 2021; 24:4703-4714. [PMID: 34724011 DOI: 10.1039/d1cp03399a] [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
Aqueous dispersions of geometrically anisometric, nano-sized sodium-montmorillonite (Na-Mt) display a sol-gel transition at very low solids concentrations. The microstructure of the gel formed at very low ionic strengths is considered electrostatically repulsive with a nematic character, and the gel state at ionic strengths where Debye length is of the order of particle size is conjectured to be free of physical aging. We investigated the nature of osmotically prepared Na-Mt dispersions at low ionic strength (∼10-5 M), below and above the gel point. The sol phase exhibited very low yield stress compared to the gel state, without any sign of physical aging, thus behaving as an equilibrium state. In contrast, the gel exhibited signatures of physical aging, that is, an evolving microstructure that consolidated with time when left undisturbed thus behaving as out of equilibrium state. The physical aging behaviour became more pronounced at Na-Mt concentrations far above the gel point. A critical shear rate existed, below which no stable flows were possible in the gel state representing the microstructural reorganization timescale. Overall, Na-Mt dispersions in the gel state behave like systems that were out of equilibrium with an ever-evolving microstructure, in opposition to the assumption that low ionic strength Na-Mt gels are in an equilibrium phase. The possible origin of physical aging, such as the reversible orientation of Brownian anisotropic particles, stiffening of an existing microstructure, or reorganization of microstructure towards minimal energy configuration is discussed in detail.
Collapse
Affiliation(s)
- Mohammad Shoaib
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Canada Ontario, M5S 3E5, Canada.
| | - Nahid Molaei
- Department of Materials Science and Engineering, University of Toronto, Canada Ontario, M5S 3E5, Canada
| | - Erin R Bobicki
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Canada Ontario, M5S 3E5, Canada.
| |
Collapse
|
15
|
Buyukdagli S, Podgornik R. Contribution of dipolar bridging to phospholipid membrane interactions: A mean-field analysis. J Chem Phys 2021; 154:224902. [PMID: 34241202 DOI: 10.1063/5.0053758] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We develop a model of interacting zwitterionic membranes with rotating surface dipoles immersed in a monovalent salt and implement it in a field theoretic formalism. In the mean-field regime of monovalent salt, the electrostatic forces between the membranes are characterized by a non-uniform trend: at large membrane separations, the interfacial dipoles on the opposing sides behave as like-charge cations and give rise to repulsive membrane interactions; at short membrane separations, the anionic field induced by the dipolar phosphate groups sets the behavior in the intermembrane region. The attraction of the cationic nitrogens in the dipolar lipid headgroups leads to the adhesion of the membrane surfaces via dipolar bridging. The underlying competition between the opposing field components of the individual dipolar charges leads to the non-uniform salt ion affinity of the zwitterionic membrane with respect to the separation distance; large inter-membrane separations imply anionic excess, while small nanometer-sized separations favor cationic excess. This complex ionic selectivity of zwitterionic membranes may have relevant repercussions on nanofiltration and nanofluidic transport techniques.
Collapse
Affiliation(s)
| | - Rudolf Podgornik
- School of Physical Sciences and Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
16
|
HIV-1 Entry and Membrane Fusion Inhibitors. Viruses 2021; 13:v13050735. [PMID: 33922579 PMCID: PMC8146413 DOI: 10.3390/v13050735] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/13/2021] [Accepted: 04/21/2021] [Indexed: 12/14/2022] Open
Abstract
HIV-1 (human immunodeficiency virus type 1) infection begins with the attachment of the virion to a host cell by its envelope glycoprotein (Env), which subsequently induces fusion of viral and cell membranes to allow viral entry. Upon binding to primary receptor CD4 and coreceptor (e.g., chemokine receptor CCR5 or CXCR4), Env undergoes large conformational changes and unleashes its fusogenic potential to drive the membrane fusion. The structural biology of HIV-1 Env and its complexes with the cellular receptors not only has advanced our knowledge of the molecular mechanism of how HIV-1 enters the host cells but also provided a structural basis for the rational design of fusion inhibitors as potential antiviral therapeutics. In this review, we summarize our latest understanding of the HIV-1 membrane fusion process and discuss related therapeutic strategies to block viral entry.
Collapse
|
17
|
Michalak DJ, Lösche M, Hoogerheide DP. Charge Effects Provide Ångström-Level Control of Lipid Bilayer Morphology on Titanium Dioxide Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:3970-3981. [PMID: 33761262 PMCID: PMC10995910 DOI: 10.1021/acs.langmuir.1c00214] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Interfaces between molecular organic architectures and oxidic substrates are a central feature of biosensors and applications of biomimetics in science and technology. For phospholipid bilayers, the large range of pH- and ionic strength-dependent surface charge densities adopted by titanium dioxide and other oxidic surfaces leads to a rich landscape of phenomena that provides exquisite control of membrane interactions with such substrates. Using neutron reflectometry measurements, we report sharp, reversible transitions that occur between closely surface-associated and weakly coupled states. We show that these states arise from a complex interplay of the tunable length scale of electrostatic interactions with the length scale arising from other forces that are independent of solution conditions. A generalized free energy potential, with its inputs only derived from established measurements of surface and bilayer properties, quantitatively describes these and previously reported observations concerning the unbinding of bilayers from supporting substrates.
Collapse
Affiliation(s)
- Dennis J Michalak
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Mathias Lösche
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
- Department of Biomedical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - David P Hoogerheide
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| |
Collapse
|
18
|
Pilati V, Gomide G, Gomes RC, Goya GF, Depeyrot J. Colloidal Stability and Concentration Effects on Nanoparticle Heat Delivery for Magnetic Fluid Hyperthermia. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:1129-1140. [PMID: 33443443 DOI: 10.1021/acs.langmuir.0c03052] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The heat produced by magnetic nanoparticles, when they are submitted to a time-varying magnetic field, has been used in many auspicious biotechnological applications. In the search for better performance in terms of the specific power absorption (SPA) index, researchers have studied the influence of the chemical composition, size and dispersion, shape, and exchange stiffness in morphochemical structures. Monodisperse assemblies of magnetic nanoparticles have been produced using elaborate synthetic procedures, where the product is generally dispersed in organic solvents. However, the colloidal stability of these rough dispersions has not received much attention in these studies, hampering experimental determination of the SPA. To investigate the influence of colloidal stability on the heating response of ferrofluids, we produced bimagnetic core@shell NPs chemically composed of a ZnMn mixed ferrite core covered by a maghemite shell. Aqueous ferrofluids were prepared with these samples using the electric double layer (EDL) as a strategy to maintain colloidal stability. By starting from a proper sample, ultrastable concentrated ferrofluids were achieved by both tuning the ion/counterion ratio and controlling the water content. As the colloidal stability mainly depends on the ion configuration on the surface of the magnetic nanoparticles, different levels of nanoparticle clustering are achieved by changing the ionic force and pH of the medium. Thus, the samples were submitted to two procedures of EDL destabilization, which involved dilution with an alkaline solution and a neutral pH viscous medium. The SPA results of all prepared ferrofluid samples show a reduction of up to half the efficiency of the standard sample when the ferrofluids are in a neutral pH or concentrated regime. Such results are explained in terms of magnetic dipolar interactions. Our results point to the importance of ferrofluid colloidal stability in a more reliable experimental determination of the NP heat generation performance.
Collapse
Affiliation(s)
- Vanessa Pilati
- Complex Fluids Group, Instituto de Física, Universidade de Brasília, Caixa Postal 04455, 70919-970 Brasília, Federal District, Brazil
| | - Guilherme Gomide
- Complex Fluids Group, Instituto de Física, Universidade de Brasília, Caixa Postal 04455, 70919-970 Brasília, Federal District, Brazil
| | - Rafael Cabreira Gomes
- Departamento de Física, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, Santa Catarina, Brazil
| | - Gerardo F Goya
- Instituto de Nanociencia y Materiales de Aragón (INMA), Universidad de Zaragoza, 50018 Zaragoza, Spain
| | - Jérôme Depeyrot
- Complex Fluids Group, Instituto de Física, Universidade de Brasília, Caixa Postal 04455, 70919-970 Brasília, Federal District, Brazil
| |
Collapse
|
19
|
Grossutti M, Dutcher JR. Hydration Water Structure, Hydration Forces, and Mechanical Properties of Polysaccharide Films. Biomacromolecules 2020; 21:4871-4877. [DOI: 10.1021/acs.biomac.0c01098] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Michael Grossutti
- Department of Physics, University of Guelph, Guelph, ON, Canada N1G 2W1
| | - John R. Dutcher
- Department of Physics, University of Guelph, Guelph, ON, Canada N1G 2W1
| |
Collapse
|
20
|
Cai Y, Zhang J, Xiao T, Peng H, Sterling SM, Walsh RM, Rawson S, Rits-Volloch S, Chen B. Distinct conformational states of SARS-CoV-2 spike protein. Science 2020; 369:1586-1592. [PMID: 32694201 PMCID: PMC7464562 DOI: 10.1126/science.abd4251] [Citation(s) in RCA: 826] [Impact Index Per Article: 206.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 07/14/2020] [Indexed: 12/11/2022]
Abstract
Intervention strategies are urgently needed to control the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. The trimeric viral spike (S) protein catalyzes fusion between viral and target cell membranes to initiate infection. Here, we report two cryo-electron microscopy structures derived from a preparation of the full-length S protein, representing its prefusion (2.9-angstrom resolution) and postfusion (3.0-angstrom resolution) conformations, respectively. The spontaneous transition to the postfusion state is independent of target cells. The prefusion trimer has three receptor-binding domains clamped down by a segment adjacent to the fusion peptide. The postfusion structure is strategically decorated by N-linked glycans, suggesting possible protective roles against host immune responses and harsh external conditions. These findings advance our understanding of SARS-CoV-2 entry and may guide the development of vaccines and therapeutics.
Collapse
Affiliation(s)
- Yongfei Cai
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Jun Zhang
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Tianshu Xiao
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Hanqin Peng
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Sarah M Sterling
- The Harvard Cryo-EM Center for Structural Biology, Harvard Medical School, Boston, MA 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Richard M Walsh
- The Harvard Cryo-EM Center for Structural Biology, Harvard Medical School, Boston, MA 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Shaun Rawson
- The Harvard Cryo-EM Center for Structural Biology, Harvard Medical School, Boston, MA 02115, USA
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
- SBGrid Consortium, Harvard Medical School, Boston, MA 02115, USA
| | - Sophia Rits-Volloch
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA
| | - Bing Chen
- Division of Molecular Medicine, Boston Children's Hospital, Boston, MA 02115, USA.
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| |
Collapse
|
21
|
Buyukdagli S, Podgornik R. Interactions between zwitterionic membranes in complex electrolytes. Phys Rev E 2020; 102:012806. [PMID: 32795042 DOI: 10.1103/physreve.102.012806] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 07/06/2020] [Indexed: 06/11/2023]
Abstract
We investigate the electrostatic interactions of zwitterionic membranes immersed in mixed electrolytes composed of mono- and multivalent ions. We show that the presence of monovalent salt is a necessary condition for the existence of a finite electrostatic force on the membrane. As a result, the mean-field membrane pressure originating from the surface dipoles exhibits a nonuniform salt dependence, characterized by an enhancement for dilute salt conditions and a decrease at intermediate salt concentrations. On addition of multivalent cations to the submolar salt solution, the separate interactions of these cations with the opposite charges of the surface dipoles makes the intermembrane pressure more repulsive at low membrane separation distances and strongly attractive at intermediate distances, resulting in a discontinuous like-charge binding transition followed by the membrane binding transition. By extending our formalism to account for correlation corrections associated with large salt concentrations, we show that membranes of high surface dipole density immersed in molar salt solutions may undergo a membrane binding transition even without the multivalent cations. Hence, the tuning of the surface polarization forces by membrane engineering can be an efficient way to adjust the equilibrium configuration of dipolar membranes in concentrated salt solutions.
Collapse
Affiliation(s)
| | - Rudolf Podgornik
- School of Physical Sciences and Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- CAS Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences (CAS), Beijing 100190, China
- Department of Physics, Faculty of Mathematics and Physics, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| |
Collapse
|
22
|
Barrett CT, Dutch RE. Viral Membrane Fusion and the Transmembrane Domain. Viruses 2020; 12:v12070693. [PMID: 32604992 PMCID: PMC7412173 DOI: 10.3390/v12070693] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 06/24/2020] [Accepted: 06/25/2020] [Indexed: 01/05/2023] Open
Abstract
Initiation of host cell infection by an enveloped virus requires a viral-to-host cell membrane fusion event. This event is mediated by at least one viral transmembrane glycoprotein, termed the fusion protein, which is a key therapeutic target. Viral fusion proteins have been studied for decades, and numerous critical insights into their function have been elucidated. However, the transmembrane region remains one of the most poorly understood facets of these proteins. In the past ten years, the field has made significant advances in understanding the role of the membrane-spanning region of viral fusion proteins. We summarize developments made in the past decade that have contributed to the understanding of the transmembrane region of viral fusion proteins, highlighting not only their critical role in the membrane fusion process, but further demonstrating their involvement in several aspects of the viral lifecycle.
Collapse
|
23
|
Cai Y, Zhang J, Xiao T, Peng H, Sterling SM, Walsh RM, Rawson S, Rits-Volloch S, Chen B. Distinct conformational states of SARS-CoV-2 spike protein. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020. [PMID: 32511405 DOI: 10.1101/2020.05.16.099317] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The ongoing SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) pandemic has created urgent needs for intervention strategies to control the crisis. The spike (S) protein of the virus forms a trimer and catalyzes fusion between viral and target cell membranes - the first key step of viral infection. Here we report two cryo-EM structures, both derived from a single preparation of the full-length S protein, representing the prefusion (3.1Å resolution) and postfusion (3.3Å resolution) conformations, respectively. The spontaneous structural transition to the postfusion state under mild conditions is independent of target cells. The prefusion trimer forms a tightly packed structure with three receptor-binding domains clamped down by a segment adjacent to the fusion peptide, significantly different from recently published structures of a stabilized S ectodomain trimer. The postfusion conformation is a rigid tower-like trimer, but decorated by N-linked glycans along its long axis with almost even spacing, suggesting possible involvement in a mechanism protecting the virus from host immune responses and harsh external conditions. These findings advance our understanding of how SARS-CoV-2 enters a host cell and may guide development of vaccines and therapeutics.
Collapse
|
24
|
Sahu S, Talele P, Patra B, Verma RS, Mishra AK. A Multiparametric Fluorescence Probe to Understand the Physicochemical Properties of Small Unilamellar Lipid Vesicles in Poly(ethylene glycol)-Water Medium. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:4842-4852. [PMID: 32283935 DOI: 10.1021/acs.langmuir.9b03902] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
FDAPT (2-formyl-5-(4'-N,N-dimethylaminophenyl)thiophene) efficiently senses the minimum alteration of lipid bilayer microenvironment with all six different fluorescence parameters namely emission wavelength, fluorescence intensity, steady-state anisotropy, and their corresponding time-dependent parameters (Sahu et al., J. Phys. Chem. B 2018, 122, 7308-7318). In the present work, the effect of poly(ethylene glycol) on the small unilamellar vesicle is demonstrated with the emission behavior of the FDAPT probe. A medium and a high molecular weight PEG were chosen to perturb the lipid vesicles. The alteration of the bilayer polarity, water content inside bilayer, lipid packing density in the perturbed vesicles reflect significant changes in different fluorescence parameters of FDAPT probe. The effect of PEG on the unilamellar vesicle was rationalized with the alteration of the emission behavior, fluorescence lifetime, steady-state anisotropy and anisotropy decay of the probe. The simple and convenient fluorescence measurements provide new insights into the effect of PEG on the packing density, water volume, micro polarity, and microviscosity of the small unilamellar vesicle. The physiological understanding was extended to rationalize the cryoprotecting behavior of PEG.
Collapse
Affiliation(s)
- Saugata Sahu
- Department of Chemistry, Indian Institute of Technology Madras, Sardar Patel Road, Adyar, Chennai-600036, Tamil Nadu India
| | - Paurnima Talele
- Department of Chemistry, Indian Institute of Technology Madras, Sardar Patel Road, Adyar, Chennai-600036, Tamil Nadu India
| | - Bamadeb Patra
- Department of Biotechnology, Indian Institute of Technology Madras, Sardar Patel Road, Adyar, Chennai-600036, Tamil Nadu India
| | - Rama Shanker Verma
- Department of Biotechnology, Indian Institute of Technology Madras, Sardar Patel Road, Adyar, Chennai-600036, Tamil Nadu India
| | - Ashok Kumar Mishra
- Department of Chemistry, Indian Institute of Technology Madras, Sardar Patel Road, Adyar, Chennai-600036, Tamil Nadu India
| |
Collapse
|
25
|
Membrane Adhesion via Glycolipids Occurs for Abundant Saccharide Chemistries. Biophys J 2020; 118:1602-1611. [PMID: 32097623 DOI: 10.1016/j.bpj.2020.02.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 01/29/2020] [Accepted: 02/05/2020] [Indexed: 01/03/2023] Open
Abstract
Membrane-bound oligosaccharides with specific chemistries are known to promote tight adhesion between adjacent membranes via the formation of weak saccharide bonds. However, in the literature, one can find scattered evidence that other, more abundant saccharide chemistries exhibit similar behavior. Here, the influence of various glycolipids on the interaction between adjacent membranes is systematically investigated with the help of small- and wide-angle x-ray scattering and complementary neutron diffraction experiments. Added electrostatic repulsion between the membrane surfaces is used to identify the formation of saccharide bonds and to challenge their stability against tensile stress. Some of the saccharide headgroup types investigated are able to bind adjacent membranes together, but this ability has no significant influence on the membrane bending rigidity. Our results indicate that glycolipid-mediated membrane adhesion is a highly abundant phenomenon and therefore potentially of great biological relevance.
Collapse
|
26
|
Balchunas AJ, Cabanas RA, Zakhary MJ, Gibaud T, Fraden S, Sharma P, Hagan MF, Dogic Z. Equation of state of colloidal membranes. SOFT MATTER 2019; 15:6791-6802. [PMID: 31408077 DOI: 10.1039/c9sm01054h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In the presence of a non-adsorbing polymer, monodisperse rod-like colloids assemble into one-rod-length thick liquid-like monolayers, called colloidal membranes. The density of the rods within a colloidal membrane is determined by a balance between the osmotic pressure exerted by the enveloping polymer suspension and the repulsion between the colloidal rods. We developed a microfluidic device for continuously observing an isolated membrane while dynamically controlling the osmotic pressure of the polymer suspension. Using this technology we measured the membrane rod density over a range of osmotic pressures than is wider that what is accessible in equilibrium samples. With increasing density we observed a first-order phase transition, in which the in-plane membrane order transforms from a 2D fluid into a 2D solid. In the limit of low osmotic pressures, we measured the rate at which individual rods evaporate from the membrane. The developed microfluidic technique could have wide applicability for in situ investigation of various soft materials and how their properties depend on the solvent composition.
Collapse
|
27
|
Chen B. Molecular Mechanism of HIV-1 Entry. Trends Microbiol 2019; 27:878-891. [PMID: 31262533 DOI: 10.1016/j.tim.2019.06.002] [Citation(s) in RCA: 161] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 05/20/2019] [Accepted: 06/05/2019] [Indexed: 11/19/2022]
Abstract
HIV-1 envelope glycoprotein [Env; trimeric (gp160)3 cleaved to (gp120/gp41)3] attaches the virion to a susceptible cell and induces fusion of viral and cell membranes to initiate infection. It interacts with the primary receptor CD4 and coreceptor (e.g., chemokine receptor CCR5 or CXCR4) to allow viral entry by triggering large structural rearrangements and unleashing the fusogenic potential of gp41 to induce membrane fusion. Recent advances in structural biology of HIV-1 Env and its complexes with the cellular receptors have revealed molecular details of HIV-1 entry and yielded new mechanistic insights. In this review, I summarize our latest understanding of the HIV-1 membrane fusion process and discuss possible pathways for productive viral entry.
Collapse
Affiliation(s)
- Bing Chen
- Division of Molecular Medicine, Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, 3 Blackfan Street, Boston, MA 02115, USA.
| |
Collapse
|
28
|
Pinto OA, Disalvo EA. A new model for lipid monolayer and bilayers based on thermodynamics of irreversible processes. PLoS One 2019; 14:e0212269. [PMID: 30947264 PMCID: PMC6448890 DOI: 10.1371/journal.pone.0212269] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Accepted: 01/30/2019] [Indexed: 11/29/2022] Open
Abstract
Lipid monolayers are used as experimental model systems to study the physical chemical properties of biomembranes. With this purpose, surface pressure/area per molecule isotherms provide a way to obtain information on packing and compressibility properties of the lipids. These isotherms have been interpreted considering the monolayer as a two dimensional ideal or van der Waals gas without contact with the water phase. These modelistic approaches do not fit the experimental results. Based on Thermodynamics of Irreversible Processes (TIP), the expansion/compression process is interpreted in terms of coupled phenomena between area changes and water fluxes between a bidimensional solution of hydrated head groups in the monolayer and the bulk solution. The formalism obtained can reproduce satisfactorily the surface pressure/area per lipid isotherms of monolayer in different states and also can explain the area expansion and compression produced in particles enclosed by bilayers during osmotic fluxes. This novel approach gives relevance to the lipid-water interaction in restricted media near the membrane and provides a formalism to understand the thermodynamic and kinetic response of biointerphases to biological effectors.
Collapse
Affiliation(s)
- O. A. Pinto
- Instituto de Bionanotecnología del NOA (INBIONATEC), Universidad Nacional de Santiago de Estero (UNSE- CONICET), Villa el Zanjón, Santiago del Estero, Argentina
| | - E. A. Disalvo
- Laboratorio de Biointerfases y Sistemas Biomiméticos, Centro de Investigaciones en Biofisica Aplicada y Alimentos (CIBAAL) (UNSE-CONICET), Villa el Zanjón, Santiago del Estero, Argentina
| |
Collapse
|
29
|
Rodriguez-Loureiro I, Latza VM, Fragneto G, Schneck E. Conformation of Single and Interacting Lipopolysaccharide Surfaces Bearing O-Side Chains. Biophys J 2019; 114:1624-1635. [PMID: 29642032 DOI: 10.1016/j.bpj.2018.02.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 02/08/2018] [Accepted: 02/13/2018] [Indexed: 10/17/2022] Open
Abstract
The outer surfaces of Gram-negative bacteria are composed of lipopolysaccharide (LPS) molecules exposing oligo- and polysaccharides to the aqueous environment. This unique, structurally complex biological interface is of great scientific interest as it mediates the interaction of bacteria with antimicrobial agents as well as with neighboring bacteria in colonies and biofilms. Structural studies on LPS surfaces, however, have so far dealt almost exclusively with rough mutant LPS of reduced molecular complexity and limited biological relevance. Here, by using neutron reflectometry, we structurally characterize planar monolayers of wild-type LPS from Escherichia coli O55:B5 featuring strain-specific O-side chains in the presence and absence of divalent cations and under controlled interaction conditions. The model used for the reflectivity analysis is self-consistent and based on the volume fraction profiles of all chemical components. The saccharide profiles are found to be bimodal, with dense inner oligosaccharides and more dilute, extended O-side chains. For interacting LPS monolayers, we establish the pressure-distance curve and determine the distance-dependent saccharide conformation.
Collapse
Affiliation(s)
| | - Victoria M Latza
- Biomaterials Department, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Giovanna Fragneto
- Large Scale Structures (LSS) Group, Institut Laue-Langevin, Grenoble, France
| | - Emanuel Schneck
- Biomaterials Department, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
| |
Collapse
|
30
|
Schlaich A, Dos Santos AP, Netz RR. Simulations of Nanoseparated Charged Surfaces Reveal Charge-Induced Water Reorientation and Nonadditivity of Hydration and Mean-Field Electrostatic Repulsion. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:551-560. [PMID: 30571136 DOI: 10.1021/acs.langmuir.8b03474] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
We perform atomistic simulations of nanometer-separated charged surfaces in the presence of monovalent counterions at fixed water chemical potential. The counterion density profiles are well described by a modified Poisson-Boltzmann (MPB) approach that accounts for nonelectrostatic ion-surface interactions, while the effects of smeared-out surface-charge distributions and dielectric profiles are found to be relatively unimportant. The simulated surface interactions are for weakly charged surfaces well described by the additive contributions of hydration and MPB repulsions, but already for a moderate surface charge density of σ = -0.77 e/nm2 this additivity breaks down. This we rationalize by a combination of different effects, namely, counterion correlations as well as the surface charge-induced reorientation of hydration water, which modifies the effective water dielectric constant as well as the hydration repulsion.
Collapse
Affiliation(s)
- Alexander Schlaich
- Laboratoire Interdisciplinaire de Physique, CNRS and Université Grenoble Alpes, UMR CNRS 5588, 38000 Grenoble , France
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| | - Alexandre P Dos Santos
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
- Instituto de Física , Universidade Federal do Rio Grande do Sul , CEP 91501-970, 15051 Porto Alegre , Brazil
| | - Roland R Netz
- Fachbereich Physik , Freie Universität Berlin , Arnimallee 14 , 14195 Berlin , Germany
| |
Collapse
|
31
|
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.
Collapse
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
| |
Collapse
|
32
|
Wolde-Kidan A, Pham QD, Schlaich A, Loche P, Sparr E, Netz RR, Schneck E. Influence of polar co-solutes and salt on the hydration of lipid membranes. Phys Chem Chem Phys 2019; 21:16989-17000. [DOI: 10.1039/c9cp01953g] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The influence of the co-solutes TMAO, urea, and NaCl on the hydration repulsion between lipid membranes is investigated in a combined experimental/simulation approach.
Collapse
Affiliation(s)
| | - Quoc Dat Pham
- Division of Physical Chemistry
- Chemistry Department
- Lund University
- 22100 Lund
- Sweden
| | | | - Philip Loche
- Fachbereich Physik
- Freie Universität Berlin
- 14195 Berlin
- Germany
| | - Emma Sparr
- Division of Physical Chemistry
- Chemistry Department
- Lund University
- 22100 Lund
- Sweden
| | - Roland R. Netz
- Fachbereich Physik
- Freie Universität Berlin
- 14195 Berlin
- Germany
| | - Emanuel Schneck
- Biomaterials Department
- Max Planck Institute of Colloids and Interfaces
- 14476 Potsdam
- Germany
| |
Collapse
|
33
|
|
34
|
Cabreira Gomes R, Ferreira da Silva A, Kouyaté M, Demouchy G, Mériguet G, Aquino R, Dubois E, Nakamae S, Roger M, Depeyrot J, Perzynski R. Thermodiffusion of repulsive charged nanoparticles - the interplay between single-particle and thermoelectric contributions. Phys Chem Chem Phys 2018; 20:16402-16413. [PMID: 29873364 DOI: 10.1039/c8cp02558d] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Thermodiffusion of different ferrite nanoparticles (NPs), ∼10 nm in diameter, is explored in tailor-made aqueous dispersions stabilized by electrostatic interparticle interactions. In the dispersions, electrosteric repulsion is the dominant force, which is tuned by an osmotic-stress technique, i.e. controlling of osmotic pressure Π, pH and ionic strength. It is then possible to map Π and the NPs' osmotic compressibility χ in the dispersion with a Carnahan-Starling formalism of effective hard spheres (larger than the NPs' core). The NPs are here dispersed with two different surface ionic species, either at pH ∼ 2 or 7, leading to a surface charge, either positive or negative. Their Ludwig-Soret ST coefficient together with their mass diffusion Dm coefficient are determined experimentally by forced Rayleigh scattering. All probed NPs display a thermophilic behavior (ST < 0) regardless of the ionic species used to cover the surface. We determine the NPs' Eastman entropy of transfer and the Seebeck (thermoelectric) contribution to the measured Ludwig-Soret coefficient in these ionic dispersions. The NPs' Eastman entropy of transfer ŝNP is interpreted through the electrostatic and hydration contributions of the ionic shell surrounding the NPs.
Collapse
|
35
|
Shadrack Jabes B, Klein R, Delle Site L. Structural Locality and Early Stage of Aggregation of Micelles in Water: An Adaptive Resolution Molecular Dynamics Study. ADVANCED THEORY AND SIMULATIONS 2018. [DOI: 10.1002/adts.201800025] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- B. Shadrack Jabes
- Institute for Mathematics Freie Universität Berlin D‐14195 Berlin Germany
| | - Rupert Klein
- Institute for Mathematics Freie Universität Berlin D‐14195 Berlin Germany
| | - Luigi Delle Site
- Institute for Mathematics Freie Universität Berlin D‐14195 Berlin Germany
| |
Collapse
|
36
|
Chung PJ, Song C, Deek J, Miller HP, Li Y, Choi MC, Wilson L, Feinstein SC, Safinya CR. Comparison between 102k and 20k Poly(ethylene oxide) Depletants in Osmotic Pressure Measurements of Interfilament Forces in Cytoskeletal Systems. ACS Macro Lett 2018; 7:228-232. [PMID: 35610898 DOI: 10.1021/acsmacrolett.7b00937] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The proliferation of successful, cell-free reconstitutions of cytoskeletal networks have prompted measurements of forces between network elements via induced osmotic pressure by the addition of depletants. Indeed, it was through osmotic pressurization that Tau, an intrinsically disordered protein found in neuronal axons, was recently discovered to mediate two distinct microtubule (MT) bundle states, one widely spaced and a second tightly packed, separated by an energy barrier due to polyelectrolyte repulsions between opposing Tau projection domains on neighboring MT surfaces. Here, we compare interfilament force measurements in Tau coated MT bundles using PEO20k (poly(ethylene oxide), Mw = 20000), a commonly used inert depletant, and recently published measurements with PEO102k. While force measurements with either depletant reveals the transition between the two bundled states, measurements with PEO20k cannot recapitulate the correct critical pressure (Pc) at which widely spaced MT bundles transition to tightly packed MT bundles due to depletant penetration into widely spaced bundles below Pc. Surprisingly, upon transitioning to the tightly packed bundle state data from both depletants are in quantitative agreement indicative of expulsion of the smaller PEO20k depletant, but only at distances comparable or less than the PEO20k radius of gyration, significantly smaller than the effective diameter of PEO20k. While PEO102k (with size larger than the wall-to-wall distance between MTs in bundles) can more accurately capture the force response behavior at low to intermediate pressures (<104 Pa), measurements with PEO20k, beyond the overlap regime with PEO102k, extend the achievable osmotic pressure range into the higher-pressure regime (∼5 × 104 Pa). The data underscores the importance of the use of polymeric depletants of different sizes to elucidate force response behavior of cytoskeletal filamentous networks over a more complete extended pressure range.
Collapse
Affiliation(s)
| | | | | | | | | | - Myung Chul Choi
- Department
of Bio and Brain Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 305-701, Republic of Korea
| | | | | | | |
Collapse
|
37
|
Micciulla S, Gerelli Y, Campbell RA, Schneck E. A Versatile Method for the Distance-Dependent Structural Characterization of Interacting Soft Interfaces by Neutron Reflectometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:789-800. [PMID: 29039954 DOI: 10.1021/acs.langmuir.7b02971] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Interactions between soft interfaces govern the behavior of emulsions and foams and crucially influence the functions of biological entities like membranes. To understand the character of these interactions, detailed insight into the interfaces' structural response in terms of molecular arrangements and conformations is often essential. This requires the realization of controlled interaction conditions and surface-sensitive techniques capable of resolving the structure of buried interfaces. Here, we present a new approach to determine the distance-dependent structure of interacting soft interfaces by neutron reflectometry. A solid/water interface and a water/oil interface are functionalized independently and initially macroscopically separated. They are then brought into contact and structurally characterized under interacting conditions. The nanometric distance between the two interfaces can be varied via the exertion of osmotic pressures. Our first experiments on lipid-anchored polymer brushes interacting across water with solid-grafted polyelectrolyte brushes and with bare silicon surfaces reveal qualitatively different interaction scenarios depending on the chemical composition of the two involved interfaces.
Collapse
Affiliation(s)
- Samantha Micciulla
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam, Germany
- Institut Laue-Langevin , 38000 Grenoble, France
| | | | | | - Emanuel Schneck
- Max Planck Institute of Colloids and Interfaces , 14476 Potsdam, Germany
| |
Collapse
|
38
|
Biswas R, Bagchi B. Anomalous water dynamics at surfaces and interfaces: synergistic effects of confinement and surface interactions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:013001. [PMID: 29205175 DOI: 10.1088/1361-648x/aa9b1d] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In nature, water is often found in contact with surfaces that are extended on the scale of molecule size but small on a macroscopic scale. Examples include lipid bilayers and reverse micelles as well as biomolecules like proteins, DNA and zeolites, to name a few. While the presence of surfaces and interfaces interrupts the continuous hydrogen bond network of liquid water, confinement on a mesoscopic scale introduces new features. Even when extended on a molecular scale, natural and biological surfaces often have features (like charge, hydrophobicity) that vary on the scale of the molecular diameter of water. As a result, many new and exotic features, which are not seen in the bulk, appear in the dynamics of water close to the surface. These different behaviors bear the signature of both water-surface interactions and of confinement. In other words, the altered properties are the result of the synergistic effects of surface-water interactions and confinement. Ultrafast spectroscopy, theoretical modeling and computer simulations together form powerful synergistic approaches towards an understanding of the properties of confined water in such systems as nanocavities, reverse micelles (RMs), water inside and outside biomolecules like proteins and DNA, and also between two hydrophobic walls. We shall review the experimental results and place them in the context of theory and simulations. For water confined within RMs, we discuss the possible interference effects propagating from opposite surfaces. Similar interference is found to give rise to an effective attractive force between two hydrophobic surfaces immersed and kept fixed at a separation of d, with the force showing an exponential dependence on this distance. For protein and DNA hydration, we shall examine a multitude of timescales that arise from frustration effects due to the inherent heterogeneity of these surfaces. We pay particular attention to the role of orientational correlations and modification of the same due to interaction with the surfaces.
Collapse
|
39
|
Schlaich A, Kappler J, Netz RR. Hydration Friction in Nanoconfinement: From Bulk via Interfacial to Dry Friction. NANO LETTERS 2017; 17:5969-5976. [PMID: 28910108 DOI: 10.1021/acs.nanolett.7b02000] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The viscous properties of nanoscopically confined water are important when hydrated surfaces in close contact are sheared against each other. Numerous experiments have probed the friction between atomically flat hydrated surfaces in the subnanometer separation regime and suggested an increased water viscosity, but the value of the effective viscosity of ultraconfined water, the mechanism of hydration layer friction, and the crossover to the dry friction limit are unclear. We study the shear friction between polar surfaces by extensive nonequilibrium molecular dynamics simulations in the linear-response regime at low shearing velocity, which is the relevant regime for typical biological applications. With decreasing water film thickness we find three consecutive friction regimes: For thick films friction is governed by bulk water viscosity. At separations of about a nanometer the highly viscous interfacial water layers dominate and increase the surface friction, while at the transition to the dry friction limit interfacial slip sets in. Based on our simulation results, we construct a confinement-dependent friction model which accounts for the additive friction contributions from bulklike water, interfacial water layers, and interfacial slip and which is valid for arbitrary water film thickness.
Collapse
Affiliation(s)
- Alexander Schlaich
- Fachbereich Physik, Freie Universität Berlin , Arnimallee 14, 14195 Berlin, Germany
| | - Julian Kappler
- Fachbereich Physik, Freie Universität Berlin , Arnimallee 14, 14195 Berlin, Germany
| | - Roland R Netz
- Fachbereich Physik, Freie Universität Berlin , Arnimallee 14, 14195 Berlin, Germany
| |
Collapse
|
40
|
Nallet F. Surfactant films in lyotropic lamellar (and related) phases: Fluctuations and interactions. Adv Colloid Interface Sci 2017; 247:363-373. [PMID: 28732556 DOI: 10.1016/j.cis.2017.06.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 06/21/2017] [Indexed: 10/19/2022]
Abstract
The analogy between soap films thinning under border capillary suction and lamellar stacks of surfactant bilayers dehydrated by osmotic stress is explored, in particular in the highly dehydrated limit where the soap film becomes a Newton black film. The nature of short-range repulsive interactions between surfactant-covered interfaces and acting across water channels in both cases will be discussed.
Collapse
|
41
|
Rodriguez-Loureiro I, Scoppola E, Bertinetti L, Barbetta A, Fragneto G, Schneck E. Neutron reflectometry yields distance-dependent structures of nanometric polymer brushes interacting across water. SOFT MATTER 2017; 13:5767-5777. [PMID: 28766679 DOI: 10.1039/c7sm01066d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The interaction between surfaces displaying end-grafted hydrophilic polymer brushes plays important roles in biology and in many wet-technological applications. In this context, the conformation of the brushes upon their mutual approach is crucial, because it affects interaction forces and the brushes' shear-tribological properties. While this aspect has been addressed by theory, experimental data on polymer conformations under confinement are difficult to obtain. Here, we study interacting planar brushes of hydrophilic polymers with defined length and grafting density. Via ellipsometry and neutron reflectometry we obtain pressure-distance curves and determine distance-dependent polymer conformations in terms of brush compression and reciprocative interpenetration. While the pressure-distance curves are satisfactorily described by the Alexander-de-Gennes model, the pronounced brush interpenetration as seen by neutron reflectometry motivates detailed simulation-based studies capable of treating brush interpenetration on a quantitative level.
Collapse
|
42
|
|
43
|
Synchrotron small-angle X-ray scattering and electron microscopy characterization of structures and forces in microtubule/Tau mixtures. Methods Cell Biol 2017; 141:155-178. [PMID: 28882300 DOI: 10.1016/bs.mcb.2017.06.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Abstract
Tau, a neuronal protein known to bind to microtubules and thereby regulate microtubule dynamic instability, has been shown recently to not only undergo conformational transitions on the microtubule surface as a function of increasing microtubule coverage density (i.e., with increasing molar ratio of Tau to tubulin dimers) but also to mediate higher-order microtubule architectures, mimicking fascicles of microtubules found in the axon initial segment. These discoveries would not have been possible without fine structure characterization of microtubules, with and without applied osmotic pressure through the use of depletants. Herein, we discuss the two primary techniques used to elucidate the structure, phase behavior, and interactions in microtubule/Tau mixtures: transmission electron microscopy and synchrotron small-angle X-ray scattering. While the former is able to provide striking qualitative images of bundle morphologies and vacancies, the latter provides angstrom-level resolution of bundle structures and allows measurements in the presence of in situ probes, such as osmotic depletants. The presented structural characterization methods have been applied both to equilibrium mixtures, where paclitaxel is used to stabilize microtubules, and also to dissipative nonequilibrium mixtures at 37°C in the presence of GTP and lacking paclitaxel.
Collapse
|
44
|
Case R, Schollmeyer H, Kohl P, Sirota EB, Pynn R, Ewert KE, Safinya CR, Li Y. Hydration forces between aligned DNA helices undergoing B to A conformational change: In-situ X-ray fiber diffraction studies in a humidity and temperature controlled environment. J Struct Biol 2017; 200:283-292. [PMID: 28734842 DOI: 10.1016/j.jsb.2017.07.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2017] [Revised: 07/08/2017] [Accepted: 07/18/2017] [Indexed: 10/19/2022]
Abstract
Hydration forces between DNA molecules in the A- and B-Form were studied using a newly developed technique enabling simultaneous in situ control of temperature and relative humidity. X-ray diffraction data were collected from oriented calf-thymus DNA fibers in the relative humidity range of 98%-70%, during which DNA undergoes the B- to A-form transition. Coexistence of both forms was observed over a finite humidity range at the transition. The change in DNA separation in response to variation in humidity, i.e. change of chemical potential, led to the derivation of a force-distance curve with a characteristic exponential decay constant of∼2Å for both A- and B-DNA. While previous osmotic stress measurements had yielded similar force-decay constants, they were limited to B-DNA with a surface separation (wall-to-wall distance) typically>5Å. The current investigation confirms that the hydration force remains dominant even in the dry A-DNA state and at surface separation down to∼1.5Å, within the first hydration shell. It is shown that the observed chemical potential difference between the A and B states could be attributed to the water layer inside the major and minor grooves of the A-DNA double helices, which can partially interpenetrate each other in the tightly packed A phase. The humidity-controlled X-ray diffraction method described here can be employed to perform direct force measurements on a broad range of biological structures such as membranes and filamentous protein networks.
Collapse
Affiliation(s)
- Ryan Case
- Materials, Physics and Molecular, Cellular and Developmental Biology Departments, University of California at Santa Barbara, CA 93106, United States
| | - Hauke Schollmeyer
- Materials, Physics and Molecular, Cellular and Developmental Biology Departments, University of California at Santa Barbara, CA 93106, United States
| | - Phillip Kohl
- Materials Research Laboratory, University of California at Santa Barbara, CA 93106, United States
| | - Eric B Sirota
- Corporate Strategic Research, ExxonMobil Research and Engineering Co., Annandale, NJ 08801, United States
| | - Roger Pynn
- Department of Physics and Center for the Exploration of Energy and Matter, Indiana University, Bloomington, IN 47408, United States; Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Kai E Ewert
- Materials, Physics and Molecular, Cellular and Developmental Biology Departments, University of California at Santa Barbara, CA 93106, United States
| | - Cyrus R Safinya
- Materials, Physics and Molecular, Cellular and Developmental Biology Departments, University of California at Santa Barbara, CA 93106, United States.
| | - Youli Li
- Materials Research Laboratory, University of California at Santa Barbara, CA 93106, United States.
| |
Collapse
|
45
|
Kanduč M, Schlaich A, de Vries AH, Jouhet J, Maréchal E, Demé B, Netz RR, Schneck E. Tight cohesion between glycolipid membranes results from balanced water-headgroup interactions. Nat Commun 2017; 8:14899. [PMID: 28367975 PMCID: PMC5382269 DOI: 10.1038/ncomms14899] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2016] [Accepted: 02/07/2017] [Indexed: 01/20/2023] Open
Abstract
Membrane systems that naturally occur as densely packed membrane stacks contain high amounts of glycolipids whose saccharide headgroups display multiple small electric dipoles in the form of hydroxyl groups. Experimentally, the hydration repulsion between glycolipid membranes is of much shorter range than that between zwitterionic phospholipids whose headgroups are dominated by a single large dipole. Using solvent-explicit molecular dynamics simulations, here we reproduce the experimentally observed, different pressure-versus-distance curves of phospholipid and glycolipid membrane stacks and show that the water uptake into the latter is solely driven by the hydrogen bond balance involved in non-ideal water/sugar mixing. Water structuring effects and lipid configurational perturbations, responsible for the longer-range repulsion between phospholipid membranes, are inoperative for the glycolipids. Our results explain the tight cohesion between glycolipid membranes at their swelling limit, which we here determine by neutron diffraction, and their unique interaction characteristics, which are essential for the biogenesis of photosynthetic membranes. Glycolipids are commonly found in densely stacked biological membranes, which show unusually strong self-cohesion compared to phospholipid membranes. Here, the authors attribute this phenomenon to the lack of long-range repulsion between glycolipid membranes, a consequence of the headgroup architecture.
Collapse
Affiliation(s)
- Matej Kanduč
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin, Germany.,Department of Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - Alexander Schlaich
- Department of Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - Alex H de Vries
- Groningen Biomolecular Sciences and Biotechnology (GBB) Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Juliette Jouhet
- Laboratoire de Physiologie Cellulaire et Végétale, CNRS, CEA, INRA, Université Grenoble Alpes, CEA Grenoble, 17 rue des Martyrs, F-38000 Grenoble, France
| | - Eric Maréchal
- Laboratoire de Physiologie Cellulaire et Végétale, CNRS, CEA, INRA, Université Grenoble Alpes, CEA Grenoble, 17 rue des Martyrs, F-38000 Grenoble, France
| | - Bruno Demé
- Institut Laue-Langevin, 71 avenue des Martyrs, F-38042 Grenoble Cedex 9, France
| | - Roland R Netz
- Department of Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - Emanuel Schneck
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, D-14476 Potsdam, Germany
| |
Collapse
|
46
|
Grossutti M, Bergmann E, Baylis B, Dutcher JR. Equilibrium Swelling, Interstitial Forces, and Water Structuring in Phytoglycogen Nanoparticle Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:2810-2816. [PMID: 28244760 DOI: 10.1021/acs.langmuir.7b00025] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Phytoglycogen is a highly branched polymer of glucose that forms dendrimeric nanoparticles. This special structure leads to a strong interaction with water that produces exceptional properties such as high water retention, low viscosity, and high stability of aqueous dispersions. We have used ellipsometry at controlled relative humidity (RH) to measure the equilibrium swelling of ultrathin films of phytoglycogen, which directly probes the interstitial forces acting within the films. Comparison of the swelling behavior of films of highly branched phytoglycogen to that of other glucose-based polysaccharides shows that the chain architecture plays an important role in determining both the strong, short-range repulsion of the chains at low RH and the repulsive hydration forces at high RH. In particular, the length scale λ0 that characterizes the exponentially decaying hydration forces provides a quantitative, RH-independent measure of film swelling that differs significantly for different glucose-based polysaccharides. By combining ellipsometry with infrared spectroscopy, we have determined the relationship between water structuring and inter-chain separation in the highly branched phytoglycogen nanoparticles, with maintenance of a high degree of water structure as the film swells significantly at high RH. These insights into the structure-hydration relationship for phytoglycogen are essential to the development of new products and technologies based on this sustainable nanomaterial.
Collapse
Affiliation(s)
- Michael Grossutti
- Department of Physics, University of Guelph , Guelph, Ontario, Canada N1G 2W1
| | - Eric Bergmann
- Department of Physics, University of Guelph , Guelph, Ontario, Canada N1G 2W1
| | - Ben Baylis
- Department of Physics, University of Guelph , Guelph, Ontario, Canada N1G 2W1
| | - John R Dutcher
- Department of Physics, University of Guelph , Guelph, Ontario, Canada N1G 2W1
| |
Collapse
|
47
|
Cranfield CG, Berry T, Holt SA, Hossain KR, Le Brun AP, Carne S, Al Khamici H, Coster H, Valenzuela SM, Cornell B. Evidence of the Key Role of H 3O + in Phospholipid Membrane Morphology. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10725-10734. [PMID: 27668940 DOI: 10.1021/acs.langmuir.6b01988] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
This study explains the importance of the phosphate moiety and H3O+ in controlling the ionic flux through phospholipid membranes. We show that despite an increase in the H3O+ concentration when the pH is decreased, the level of ionic conduction through phospholipid bilayers is reduced. By modifying the lipid structure, we show the dominant determinant of membrane conduction is the hydrogen bonding between the phosphate oxygens on adjacent phospholipids. The modulation of conduction with pH is proposed to arise from the varying H3O+ concentrations altering the molecular area per lipid and modifying the geometry of conductive defects already present in the membrane. Given the geometrical constraints that control the lipid phase structure of membranes, these area changes predict that organisms evolving in environments with different pHs will select for different phospholipid chain lengths, as is found for organisms near highly acidic volcanic vents (short chains) or in highly alkaline salt lakes (long chains). The stabilizing effect of the hydration shells around phosphate groups also accounts for the prevalence of phospholipids across biology. Measurement of ion permeation through lipid bilayers was made tractable using sparsely tethered bilayer lipid membranes with swept frequency electrical impedance spectroscopy and ramped dc amperometry. Additional evidence of the effect of a change in pH on lipid packing density is obtained from neutron reflectometry data of tethered membranes containing perdeuterated lipids.
Collapse
Affiliation(s)
- Charles G Cranfield
- School of Life Sciences, University of Technology Sydney , Ultimo, NSW 2007, Australia
| | - Thomas Berry
- School of Life Sciences, University of Technology Sydney , Ultimo, NSW 2007, Australia
| | - Stephen A Holt
- Australian Nuclear Science and Technology Organisation , Locked Bag 2001, Kirrawee DC, New South Wales 2232, Australia
| | - Khondker R Hossain
- School of Life Sciences, University of Technology Sydney , Ultimo, NSW 2007, Australia
- Australian Nuclear Science and Technology Organisation , Locked Bag 2001, Kirrawee DC, New South Wales 2232, Australia
| | - Anton P Le Brun
- Australian Nuclear Science and Technology Organisation , Locked Bag 2001, Kirrawee DC, New South Wales 2232, Australia
| | - Sonia Carne
- SDx Tethered Membranes Pty. Ltd. , Unit 6, 30-32 Barcoo Street, Roseville, NSW 2069, Australia
| | - Heba Al Khamici
- School of Life Sciences, University of Technology Sydney , Ultimo, NSW 2007, Australia
| | - Hans Coster
- School of Chemical and Biomolecular Engineering, University of Sydney , Sydney, NSW 2006, Australia
| | - Stella M Valenzuela
- School of Life Sciences, University of Technology Sydney , Ultimo, NSW 2007, Australia
| | - Bruce Cornell
- SDx Tethered Membranes Pty. Ltd. , Unit 6, 30-32 Barcoo Street, Roseville, NSW 2069, Australia
| |
Collapse
|
48
|
Cord factor as an invisibility cloak? A hypothesis for asymptomatic TB persistence. Tuberculosis (Edinb) 2016; 101S:S2-S8. [PMID: 27743706 DOI: 10.1016/j.tube.2016.09.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mycobacterium tuberculosis (MTB) has long been known to persist in grossly normal tissues even in people with active lesions and granulomas in other parts of the body. We recently reported that post-primary TB begins as an asymptomatic infection that slowly progresses, accumulating materials for a massive necrotizing reaction that results in cavitation. This paper explores the possible roles of trehalose 6,6' dimycolate (TDM) or cord factor in the ability of MTB to persist in such lesions without producing inflammation. TDM is unique in that it has three distinct sets of biologic activities depending on its physical conformation. As a single molecule, TDM stimulates macrophage C-type lectin receptors including Mincle. TDM can also form three crystal like structures, cylindrical micelles, intercalated bilayer and monolayer, that have distinct non receptor driven activities that depend on modulation of interactions with water. In the monolayer form, TDM is highly toxic and destroys cells in minutes upon contact. The cylindrical micelles and an intercalated bilayer have surfaces composed entirely of trehalose which protect MTB from killing in macrophages. Here we review evidence that these trehalose surfaces bind water. We speculate that this immobilized water constituites of an "invisibility cloak" that facilitates the persistence of MTB in multiple cell types without producing inflammation, even in highly immune individuals.
Collapse
|
49
|
Kanduč M, Schlaich A, Schneck E, Netz RR. Water-Mediated Interactions between Hydrophilic and Hydrophobic Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:8767-8782. [PMID: 27487420 DOI: 10.1021/acs.langmuir.6b01727] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
All surfaces in water experience at short separations hydration repulsion or hydrophobic attraction, depending on the surface polarity. These interactions dominate the more long-ranged electrostatic and van der Waals interactions and are ubiquitous in biological and colloidal systems. Despite their importance in all scenarios where the surface separation is in the nanometer range, the origin of these hydration interactions is still unclear. Using atomistic solvent-explicit molecular dynamics simulations, we analyze the interaction free energies of charge-neutral model surfaces with different elastic and water-binding properties. The surface polarity is shown to be the most important parameter that not only determines the hydration properties and thereby the water contact angle of a single surface but also the surface-surface interaction and whether two surfaces attract or repel. Elastic properties of the surfaces are less important. On the basis of surface contact angles and surface-surface binding affinities, we construct a universal interaction diagram featuring three different interaction regimes-hydration repulsion, cavitation-induced attraction-and for intermediate surface polarities-dry adhesion. On the basis of scaling arguments and perturbation theory, we establish simple combination rules that predict the interaction behavior for combinations of dissimilar surfaces.
Collapse
Affiliation(s)
- Matej Kanduč
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin für Materialien und Energie , Hahn-Meitner-Platz 1, D-14109 Berlin, Germany
| | - Alexander Schlaich
- Department of Physics, Freie Universität Berlin , Arnimallee 14, D-14195 Berlin, Germany
| | - Emanuel Schneck
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, D-14476 Potsdam, Germany
| | - Roland R Netz
- Department of Physics, Freie Universität Berlin , Arnimallee 14, D-14195 Berlin, Germany
| |
Collapse
|
50
|
Dhopatkar N, Defante AP, Dhinojwala A. Ice-like water supports hydration forces and eases sliding friction. SCIENCE ADVANCES 2016; 2:e1600763. [PMID: 27574706 PMCID: PMC5001812 DOI: 10.1126/sciadv.1600763] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Accepted: 07/29/2016] [Indexed: 05/22/2023]
Abstract
The nature of interfacial water is critical in several natural processes, including the aggregation of lipids into the bilayer, protein folding, lubrication of synovial joints, and underwater gecko adhesion. The nanometer-thin water layer trapped between two surfaces has been identified to have properties that are very different from those of bulk water, but the molecular cause of such discrepancy is often undetermined. Using surface-sensitive sum frequency generation (SFG) spectroscopy, we discover a strongly coordinated water layer confined between two charged surfaces, formed by the adsorption of a cationic surfactant on the hydrophobic surfaces. By varying the adsorbed surfactant coverage and hence the surface charge density, we observe a progressively evolving water structure that minimizes the sliding friction only beyond the surfactant concentration needed for monolayer formation. At complete surfactant coverage, the strongly coordinated confined water results in hydration forces, sustains confinement and sliding pressures, and reduces dynamic friction. Observing SFG signals requires breakdown in centrosymmetry, and the SFG signal from two oppositely oriented surfactant monolayers cancels out due to symmetry. Surprisingly, we observe the SFG signal for the water confined between the two charged surfactant monolayers, suggesting that this interfacial water layer is noncentrosymmetric. The structure of molecules under confinement and its macroscopic manifestation on adhesion and friction have significance in many complicated interfacial processes prevalent in biology, chemistry, and engineering.
Collapse
|