1
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Aleksanyan M, Grafmüller A, Crea F, Georgiev VN, Yandrapalli N, Block S, Heberle J, Dimova R. Photomanipulation of Minimal Synthetic Cells: Area Increase, Softening, and Interleaflet Coupling of Membrane Models Doped with Azobenzene-Lipid Photoswitches. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2304336. [PMID: 37653602 PMCID: PMC10625111 DOI: 10.1002/advs.202304336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/24/2023] [Indexed: 09/02/2023]
Abstract
Light can effectively interrogate biological systems in a reversible and physiologically compatible manner with high spatiotemporal precision. Understanding the biophysics of photo-induced processes in bio-systems is crucial for achieving relevant clinical applications. Employing membranes doped with the photolipid azobenzene-phosphatidylcholine (azo-PC), a holistic picture of light-triggered changes in membrane kinetics, morphology, and material properties obtained from correlative studies on cell-sized vesicles, Langmuir monolayers, supported lipid bilayers, and molecular dynamics simulations is provided. Light-induced membrane area increases as high as ≈25% and a ten-fold decrease in the membrane bending rigidity is observed upon trans-to-cis azo-PC isomerization associated with membrane leaflet coupling and molecular curvature changes. Vesicle electrodeformation measurements and atomic force microscopy reveal that trans azo-PC bilayers are thicker than palmitoyl-oleoyl phosphatidylcholine (POPC) bilayers but have higher specific membrane capacitance and dielectric constant suggesting an increased ability to store electric charges across the membrane. Lastly, incubating POPC vesicles with azo-PC solutions results in the insertion of azo-PC in the membrane enabling them to become photoresponsive. All these results demonstrate that light can be used to finely manipulate the shape, mechanical and electric properties of photolipid-doped minimal cell models, and liposomal drug carriers, thus, presenting a promising therapeutic alternative for the repair of cellular disorders.
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Affiliation(s)
- Mina Aleksanyan
- Max Planck Institute of Colloids and InterfacesScience Park Golm14476PotsdamGermany
- Institute for Chemistry and BiochemistryFreie Universität Berlin14195BerlinGermany
| | - Andrea Grafmüller
- Max Planck Institute of Colloids and InterfacesScience Park Golm14476PotsdamGermany
| | - Fucsia Crea
- Department of PhysicsFreie Universität Berlin14195BerlinGermany
| | - Vasil N. Georgiev
- Max Planck Institute of Colloids and InterfacesScience Park Golm14476PotsdamGermany
| | - Naresh Yandrapalli
- Max Planck Institute of Colloids and InterfacesScience Park Golm14476PotsdamGermany
| | - Stephan Block
- Institute for Chemistry and BiochemistryFreie Universität Berlin14195BerlinGermany
| | - Joachim Heberle
- Department of PhysicsFreie Universität Berlin14195BerlinGermany
| | - Rumiana Dimova
- Max Planck Institute of Colloids and InterfacesScience Park Golm14476PotsdamGermany
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2
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Brzyska A, Korycki P, Woliński K. The carbohydrate glycosylphosphatidylinositol anchor chain under mechanical stress. Carbohydr Res 2022; 522:108702. [DOI: 10.1016/j.carres.2022.108702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 09/28/2022] [Accepted: 10/06/2022] [Indexed: 11/02/2022]
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3
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Banerjee P, Silva DV, Lipowsky R, Santer M. The importance of side branches of glycosylphosphatidylinositol anchors: a molecular dynamics perspective. Glycobiology 2022; 32:933-948. [PMID: 36197124 PMCID: PMC9620968 DOI: 10.1093/glycob/cwac037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 05/22/2022] [Accepted: 05/30/2022] [Indexed: 11/14/2022] Open
Abstract
Many proteins are anchored to the cell surface of eukaryotes using a unique family of glycolipids called glycosylphosphatidylinositol (GPI) anchors. These glycolipids also exist without a covalently bound protein, in particular on the cell surfaces of protozoan parasites where they are densely populated. GPIs and GPI-anchored proteins participate in multiple cellular processes such as signal transduction, cell adhesion, protein trafficking and pathogenesis of Malaria, Toxoplasmosis, Trypanosomiasis and prion diseases, among others. All GPIs share a common conserved glycan core modified in a cell-dependent manner with additional side glycans or phosphoethanolamine residues. Here, we use atomistic molecular dynamic simulations and perform a systematic study to evaluate the structural properties of GPIs with different side chains inserted in lipid bilayers. Our results show a flop-down orientation of GPIs with respect to the membrane surface and the presentation of the side chain residues to the solvent. This finding agrees well with experiments showing the role of the side residues as active epitopes for recognition of GPIs by macrophages and induction of GPI-glycan-specific immune responses. Protein-GPI interactions were investigated by attaching parasitic GPIs to Green Fluorescent Protein. GPIs are observed to recline on the membrane surface and pull down the attached protein close to the membrane facilitating mutual contacts between protein, GPI and the lipid bilayer. This model is efficient in evaluating the interaction of GPIs and GPI-anchored proteins with membranes and can be extended to study other parasitic GPIs and proteins and develop GPI-based immunoprophylaxis to treat infectious diseases.
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Affiliation(s)
- Pallavi Banerjee
- Department of Theory and Biosystems, Max Planck Institute of Colloids and Interfaces, Potsdam 14476, Germany.,Mathematisch-Naturwissenschaftlichen Fakultät, University of Potsdam, Potsdam 14476, Germany
| | - Daniel Varon Silva
- Department of Theory and Biosystems, Max Planck Institute of Colloids and Interfaces, Potsdam 14476, Germany
| | - Reinhard Lipowsky
- Department of Theory and Biosystems, Max Planck Institute of Colloids and Interfaces, Potsdam 14476, Germany.,Mathematisch-Naturwissenschaftlichen Fakultät, University of Potsdam, Potsdam 14476, Germany
| | - Mark Santer
- Department of Theory and Biosystems, Max Planck Institute of Colloids and Interfaces, Potsdam 14476, Germany
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4
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Abstract
Glycoscience assembles all the scientific disciplines involved in studying various molecules and macromolecules containing carbohydrates and complex glycans. Such an ensemble involves one of the most extensive sets of molecules in quantity and occurrence since they occur in all microorganisms and higher organisms. Once the compositions and sequences of these molecules are established, the determination of their three-dimensional structural and dynamical features is a step toward understanding the molecular basis underlying their properties and functions. The range of the relevant computational methods capable of addressing such issues is anchored by the specificity of stereoelectronic effects from quantum chemistry to mesoscale modeling throughout molecular dynamics and mechanics and coarse-grained and docking calculations. The Review leads the reader through the detailed presentations of the applications of computational modeling. The illustrations cover carbohydrate-carbohydrate interactions, glycolipids, and N- and O-linked glycans, emphasizing their role in SARS-CoV-2. The presentation continues with the structure of polysaccharides in solution and solid-state and lipopolysaccharides in membranes. The full range of protein-carbohydrate interactions is presented, as exemplified by carbohydrate-active enzymes, transporters, lectins, antibodies, and glycosaminoglycan binding proteins. A final section features a list of 150 tools and databases to help address the many issues of structural glycobioinformatics.
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Affiliation(s)
- Serge Perez
- Centre de Recherche sur les Macromolecules Vegetales, University of Grenoble-Alpes, Centre National de la Recherche Scientifique, Grenoble F-38041, France
| | - Olga Makshakova
- FRC Kazan Scientific Center of Russian Academy of Sciences, Kazan Institute of Biochemistry and Biophysics, Kazan 420111, Russia
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5
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Conformational preferences of triantennary and tetraantennary hybrid N-glycans in aqueous solution: Insights from 20 μs long atomistic molecular dynamic simulations. J Biomol Struct Dyn 2022; 41:3305-3320. [PMID: 35262462 DOI: 10.1080/07391102.2022.2047109] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In the current study, we have investigated the conformational dynamics of a triantennary (N-glycan1) and tetraantennary (N-glycan2) hybrid N-glycans found on the surface of the HIV glycoprotein using 20 μs long all-atom molecular dynamics (MD) simulations. The main objective of the present study is to elucidate the influence of adding a complex branch on the overall glycan structural dynamics. Our investigation suggests that the average RMSD value increases when a complex branch is added to N-glycan1. However, the RMSD distribution is relatively wider in the case of N-glycan1 compared to N-glycan2, which indicates that multiple complex branches restrict the conformational variability of glycans. A similar observation is obtained from the principal component analysis of both glycans. All the puckering states (4C1 to 1C4) of each monosaccharide except mannose are sampled in our simulations, although the 4C1 chair form is energetically more favorable than 1C4. In N-glycan1, the 1-6 linkage in the mannose branch [Man(9)-α(1-6)-Man(5)] stays in the gauche-gauche cluster, whereas it moves towards trans-gauche in N-glycan2. For both glycans, mannose branches are more flexible than the complex branches, and adding a complex branch does not influence the dynamics of the mannose branches. We have noticed that the end-to-end distance of the complex branch shortens by ∼ 10 Å in the presence of another complex branch. This suggests that in the presence of an additional complex branch, the other complex branch adopts a close folded structure. All these conformational changes involve the selective formation of inter-residue and water-mediated hydrogen-bond networks.
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6
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Singhal A, Schneible JD, Lilova RL, Hall CK, Menegatti S, Grafmüller A. A multiscale coarse-grained model to predict the molecular architecture and drug transport properties of modified chitosan hydrogels. SOFT MATTER 2020; 16:10591-10610. [PMID: 33156313 DOI: 10.1039/d0sm01243b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Hydrogels constructed with functionalized polysaccharides are of interest in a multitude of applications, chiefly the design of therapeutic and regenerative formulations. Tailoring the chemical modification of polysaccharide-based hydrogels to achieve specific drug release properties involves the optimization of many tunable parameters, including (i) the type, degree (χ), and pattern of the functional groups, (ii) the water-polymer ratio, and (iii) the drug payload. To guide the design of modified polysaccharide hydrogels for drug release, we have developed a computational toolbox that predicts the structure and physicochemical properties of acylated chitosan chains, and their impact on the transport of drug molecules. Herein, we present a multiscale coarse-grained model to investigate the structure of networks of chitosan chains modified with acetyl, butanoyl, or heptanoyl moieties, as well as the diffusion of drugs doxorubicin (Dox) and gemcitabine (Gem) through the resulting networks. The model predicts the formation of different network structures, in particular the hydrophobically-driven transition from a uniform to a cluster/channel morphology and the formation of fibers of chitin chains. The model also describes the impact of structural and physicochemical properties on drug transport, which was confirmed experimentally by measuring Dox and Gem diffusion through an ensemble of modified chitosan hydrogels.
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Affiliation(s)
- Ankush Singhal
- Department of Theory and Biosystems, Max Planck Institute for Colloids and Interfaces, Potsdam 14476, Germany.
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7
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Structural base for the transfer of GPI-anchored glycoproteins into fungal cell walls. Proc Natl Acad Sci U S A 2020; 117:22061-22067. [PMID: 32839341 DOI: 10.1073/pnas.2010661117] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The correct distribution and trafficking of proteins are essential for all organisms. Eukaryotes evolved a sophisticated trafficking system which allows proteins to reach their destination within highly compartmentalized cells. One eukaryotic hallmark is the attachment of a glycosylphosphatidylinositol (GPI) anchor to C-terminal ω-peptides, which are used as a zip code to guide a subset of membrane-anchored proteins through the secretory pathway to the plasma membrane. In fungi, the final destination of many GPI-anchored proteins is their outermost compartment, the cell wall. Enzymes of the Dfg5 subfamily catalyze the essential transfer of GPI-anchored substrates from the plasma membrane to the cell wall and discriminate between plasma membrane-resident GPI-anchored proteins and those transferred to the cell wall (GPI-CWP). We solved the structure of Dfg5 from a filamentous fungus and used in crystallo glycan fragment screening to reassemble the GPI-core glycan in a U-shaped conformation within its binding pocket. The resulting model of the membrane-bound Dfg5•GPI-CWP complex is validated by molecular dynamics (MD) simulations and in vivo mutants in yeast. The latter show that impaired transfer of GPI-CWPs causes distorted cell-wall integrity as indicated by increased chitin levels. The structure of a Dfg5•β1,3-glycoside complex predicts transfer of GPI-CWP toward the nonreducing ends of acceptor glycans in the cell wall. In addition to our molecular model for Dfg5-mediated transglycosylation, we provide a rationale for how GPI-CWPs are specifically sorted toward the cell wall by using GPI-core glycan modifications.
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8
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Banerjee P, Lipowsky R, Santer M. Coarse-Grained Molecular Model for the Glycosylphosphatidylinositol Anchor with and without Protein. J Chem Theory Comput 2020; 16:3889-3903. [PMID: 32392421 PMCID: PMC7303967 DOI: 10.1021/acs.jctc.0c00056] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Indexed: 01/17/2023]
Abstract
Glycosylphosphatidylinositol (GPI) anchors are a unique class of complex glycolipids that anchor a great variety of proteins to the extracellular leaflet of plasma membranes of eukaryotic cells. These anchors can exist either with or without an attached protein called GPI-anchored protein (GPI-AP) both in vitro and in vivo. Although GPIs are known to participate in a broad range of cellular functions, it is to a large extent unknown how these are related to GPI structure and composition. Their conformational flexibility and microheterogeneity make it difficult to study them experimentally. Simplified atomistic models are amenable to all-atom computer simulations in small lipid bilayer patches but not suitable for studying their partitioning and trafficking in complex and heterogeneous membranes. Here, we present a coarse-grained model of the GPI anchor constructed with a modified version of the MARTINI force field that is suited for modeling carbohydrates, proteins, and lipids in an aqueous environment using MARTINI's polarizable water. The nonbonded interactions for sugars were reparametrized by calculating their partitioning free energies between polar and apolar phases. In addition, sugar-sugar interactions were optimized by adjusting the second virial coefficients of osmotic pressures for solutions of glucose, sucrose, and trehalose to match with experimental data. With respect to the conformational dynamics of GPI-anchored green fluorescent protein, the accessible time scales are now at least an order of magnitude larger than for the all-atom system. This is particularly important for fine-tuning the mutual interactions of lipids, carbohydrates, and amino acids when comparing to experimental results. We discuss the prospective use of the coarse-grained GPI model for studying protein-sorting and trafficking in membrane models.
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Affiliation(s)
- Pallavi Banerjee
- Max
Planck Institute of Colloids and Interfaces, Potsdam 14476, Germany
- Institute
of Biochemistry and Biology, University
of Potsdam, Potsdam 14469, Germany
| | - Reinhard Lipowsky
- Max
Planck Institute of Colloids and Interfaces, Potsdam 14476, Germany
- Institute
of Biochemistry and Biology, University
of Potsdam, Potsdam 14469, Germany
| | - Mark Santer
- Max
Planck Institute of Colloids and Interfaces, Potsdam 14476, Germany
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9
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Kunstmann S, Engström O, Wehle M, Widmalm G, Santer M, Barbirz S. Increasing the Affinity of an O-Antigen Polysaccharide Binding Site in Shigella flexneri Bacteriophage Sf6 Tailspike Protein. Chemistry 2020; 26:7263-7273. [PMID: 32189378 PMCID: PMC7463171 DOI: 10.1002/chem.202000495] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 03/09/2020] [Indexed: 12/30/2022]
Abstract
Broad and unspecific use of antibiotics accelerates spread of resistances. Sensitive and robust pathogen detection is thus important for a more targeted application. Bacteriophages contain a large repertoire of pathogen-binding proteins. These tailspike proteins (TSP) often bind surface glycans and represent a promising design platform for specific pathogen sensors. We analysed bacteriophage Sf6 TSP that recognizes the O-polysaccharide of dysentery-causing Shigella flexneri to develop variants with increased sensitivity for sensor applications. Ligand polyrhamnose backbone conformations were obtained from 2D 1 H,1 H-trNOESY NMR utilizing methine-methine and methine-methyl correlations. They agreed well with conformations obtained from molecular dynamics (MD), validating the method for further predictions. In a set of mutants, MD predicted ligand flexibilities that were in good correlation with binding strength as confirmed on immobilized S. flexneri O-polysaccharide (PS) with surface plasmon resonance. In silico approaches combined with rapid screening on PS surfaces hence provide valuable strategies for TSP-based pathogen sensor design.
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Affiliation(s)
- Sonja Kunstmann
- Physikalische BiochemieUniversität PotsdamKarl-Liebknecht-Str. 24–2514476PotsdamGermany
- Theory and BiosystemsMax Planck Institute of Colloids and InterfacesAm Mühlenberg 114476PotsdamGermany
- Current address: Department of Biotechnology and BiomedicineTechnical University of DenmarkSøltofts Plads2800 Kgs.LyngbyDenmark
| | - Olof Engström
- Department of Organic ChemistryArrhenius LaboratoryStockholm University10691StockholmSweden
| | - Marko Wehle
- Theory and BiosystemsMax Planck Institute of Colloids and InterfacesAm Mühlenberg 114476PotsdamGermany
| | - Göran Widmalm
- Department of Organic ChemistryArrhenius LaboratoryStockholm University10691StockholmSweden
| | - Mark Santer
- Theory and BiosystemsMax Planck Institute of Colloids and InterfacesAm Mühlenberg 114476PotsdamGermany
| | - Stefanie Barbirz
- Physikalische BiochemieUniversität PotsdamKarl-Liebknecht-Str. 24–2514476PotsdamGermany
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10
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Echeverri D, Garg M, Varón Silva D, Orozco J. Phosphoglycan-sensitized platform for specific detection of anti-glycan IgG and IgM antibodies in serum. Talanta 2020; 217:121117. [PMID: 32498834 DOI: 10.1016/j.talanta.2020.121117] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/29/2020] [Accepted: 05/01/2020] [Indexed: 01/29/2023]
Abstract
Glycosylphosphatidylinositol anchored proteins (GPI-APs) are natural conjugates in the plasma membrane of eukaryotic cells that result from the attachment of a glycolipid to the C-terminus of many proteins. GPI-APs play a crucial role in cell signaling and adhesion and have implications in health and diseases. GPI-APs and GPIs without protein (free GPIs) are found in abundance on the surface of the protozoan parasite Toxoplasma gondii. The detection of anti-GPI IgG and IgM antibodies allows differentiation between toxoplasmosis patients and healthy individuals using serological assays. However, these methods are limited by their poor efficiency, cross-reactivity and need for sophisticated laboratory equipment and qualified personnel. Here, we established a label-free electrochemical glycobiosensor for the detection of anti-GPI IgG and IgM antibodies in serum from toxoplasmosis seropositive patients. This biosensor uses a synthetic GPI phosphoglycan bioreceptor immobilized on screen-printed gold electrodes through a linear alkane thiol phosphodiester. The antigen-antibody interaction was detected and quantified by electrochemical impedance spectroscopy (EIS). The resultant device showed a linear dynamic range of anti-GPI antibodies in serum ranging from 1.0 to 10.0 IU mL-1, with a limit of detection of 0.31 IU mL-1. This method also holds great potential for the detection of IgG antibodies related to other multiple medical conditions characterized by overexpression of antibodies.
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Affiliation(s)
- Danilo Echeverri
- Max Planck Tandem Group in Nanobioengineering, University of Antioquia, Complejo Ruta N, Calle 67 N° 52-20, Medellín, 050010, Colombia
| | - Monika Garg
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany
| | - Daniel Varón Silva
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany
| | - Jahir Orozco
- Max Planck Tandem Group in Nanobioengineering, University of Antioquia, Complejo Ruta N, Calle 67 N° 52-20, Medellín, 050010, Colombia.
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11
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Zhang H, Kai ELJ, Lu L. Investigating the stability of dengue virus envelope protein dimer using well-tempered metadynamics simulations. Proteins 2019; 88:643-653. [PMID: 31697409 DOI: 10.1002/prot.25844] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 10/24/2019] [Accepted: 11/03/2019] [Indexed: 12/21/2022]
Abstract
We explored the stability of the dengue virus envelope (E) protein dimer since it is widely assumed that the E protein dimer is stabilized by drug ligands or antibodies in an acidic environment, neutralizing the virus's ability to fuse with human cells. During this process, a large conformational change of the E protein dimer is required. We performed Molecular Dynamics simulations to mimic the conformational change and stability of the dimer in neutral and acidic conditions with the well-tempered metadynamics method. Furthermore, as a few neutralizing antibodies discovered from dengue patients were reported, we used the same simulation method to examine the influence of a selected antibody on the dimer stability in both neutral and acidic conditions. We also investigated the antibody's influence on a point-mutated E protein that had been reported to interrupt the protein-antibody interaction and result in more than 95% loss of the antibody's binding ability. Our simulation results are highly consistent with the experimental conclusion that binding of the antibody to the E protein dimer neutralizes the virus, especially in a low pH condition, while the mutation of W101A or N153A significantly reduces the antibody's ability in stabilizing the E protein dimer. We demonstrate that well-tempered metadynamics can be used to accurately explore the antibody's interaction on large protein complexes such as the E protein dimer, and the computational approach in this work is promising in future antibody development.
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Affiliation(s)
- Haiping Zhang
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore.,Joint Engineering Research Center for Health Big Data Intelligent Analysis Technology, Shenzhen Institutes of Advanced Technology, Shenzhen, Guangdong Province, People's Republic of China
| | - Eric L J Kai
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Lanyuan Lu
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
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12
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Georgiev VN, Grafmüller A, Bléger D, Hecht S, Kunstmann S, Barbirz S, Lipowsky R, Dimova R. Area Increase and Budding in Giant Vesicles Triggered by Light: Behind the Scene. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2018; 5:1800432. [PMID: 30128249 PMCID: PMC6096984 DOI: 10.1002/advs.201800432] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 04/18/2018] [Indexed: 06/08/2023]
Abstract
Biomembranes are constantly remodeled and in cells, these processes are controlled and modulated by an assortment of membrane proteins. Here, it is shown that such remodeling can also be induced by photoresponsive molecules. The morphological control of giant vesicles in the presence of a water-soluble ortho-tetrafluoroazobenzene photoswitch (F-azo) is demonstrated and it is shown that the shape transformations are based on an increase in membrane area and generation of spontaneous curvature. The vesicles exhibit budding and the buds can be retracted by using light of a different wavelength. In the presence of F-azo, the membrane area can increase by more than 5% as assessed from vesicle electrodeformation. To elucidate the underlying molecular mechanism and the partitioning of F-azo in the membrane, molecular dynamics simulations are employed. Comparison with theoretically calculated shapes reveals that the budded shapes are governed by curvature elasticity, that the spontaneous curvature can be decomposed into a local and a nonlocal contribution, and that the local spontaneous curvature is about 1/(2.5 µm). The results show that exo- and endocytotic events can be controlled by light and that these photoinduced processes provide an attractive method to change membrane area and morphology.
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Affiliation(s)
- Vasil N. Georgiev
- Department of Theory and Bio‐SystemsMax Planck Institute of Colloids and InterfacesScience Park Golm14424PotsdamGermany
| | - Andrea Grafmüller
- Department of Theory and Bio‐SystemsMax Planck Institute of Colloids and InterfacesScience Park Golm14424PotsdamGermany
| | - David Bléger
- Department of Chemistry & IRIS AdlershofHumboldt‐Universität zu BerlinBrook‐Taylor‐Str. 212489BerlinGermany
| | - Stefan Hecht
- Department of Chemistry & IRIS AdlershofHumboldt‐Universität zu BerlinBrook‐Taylor‐Str. 212489BerlinGermany
| | - Sonja Kunstmann
- Department of Theory and Bio‐SystemsMax Planck Institute of Colloids and InterfacesScience Park Golm14424PotsdamGermany
- Physikalische BiochemieUniversität PotsdamKarl‐Liebknecht‐Str. 24‐2514476PotsdamGermany
| | - Stefanie Barbirz
- Physikalische BiochemieUniversität PotsdamKarl‐Liebknecht‐Str. 24‐2514476PotsdamGermany
| | - Reinhard Lipowsky
- Department of Theory and Bio‐SystemsMax Planck Institute of Colloids and InterfacesScience Park Golm14424PotsdamGermany
| | - Rumiana Dimova
- Department of Theory and Bio‐SystemsMax Planck Institute of Colloids and InterfacesScience Park Golm14424PotsdamGermany
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13
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Grube M, Lee BY, Garg M, Michel D, Vilotijević I, Malik A, Seeberger PH, Varón Silva D. Synthesis of Galactosylated Glycosylphosphatidylinositol Derivatives from Trypanosoma brucei. Chemistry 2018; 24:3271-3282. [PMID: 29314341 DOI: 10.1002/chem.201705511] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Indexed: 11/09/2022]
Abstract
Trypanosoma brucei uses variant surface glycoproteins (VSGs) to evade the host immune system and ensure parasitic longevity in animals and humans. VSGs are attached to the cell membrane by complex glycosylphosphatidylinositol anchors (GPI). Distinguishing structural feature of VSG GPIs are multiple α- and β-galactosides attached to the conserved GPI core structure. T. brucei GPIs have been associated with macrophage activation and alleviation of parasitemia during infection, acting as disease onset delaying antigens. Literature reports that link structural modifications in the GPIs to changes in biological activity are contradictory. We have established a synthetic route to prepare structurally overlapping GPI derivatives bearing different T. brucei characteristic structural modifications. The GPI collection will be used to assess the effect of galactosylation and phosphorylation on T. brucei GPI immunomodulatory activity, and to perform an epitope mapping of this complex glycolipid as potential diagnostic marker for Trypanosomiasis. A strategy for the synthesis of a complete α-tetragalactoside using the 2-naphthylmethyl protecting group and for subsequent attachment of GPI fragments to peptides is presented.
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Affiliation(s)
- Maurice Grube
- Biomolecular Systems Department, Max-Planck-Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany.,Department of Biology, Chemistry and Pharmacy, Free University Berlin, Arnimallee 22, 14195, Berlin, Germany.,Current address: Science for Life Laboratory, Tomtebodavägen 23A, 17121, Stockholm, Sweden
| | - Bo-Young Lee
- Biomolecular Systems Department, Max-Planck-Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany
| | - Monika Garg
- Biomolecular Systems Department, Max-Planck-Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany.,Department of Biology, Chemistry and Pharmacy, Free University Berlin, Arnimallee 22, 14195, Berlin, Germany
| | - Dana Michel
- Biomolecular Systems Department, Max-Planck-Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany.,Department of Biology, Chemistry and Pharmacy, Free University Berlin, Arnimallee 22, 14195, Berlin, Germany
| | - Ivan Vilotijević
- Biomolecular Systems Department, Max-Planck-Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany.,Current address: Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich-Schiller-University Jena, Humboldtstr. 10, Office 310A, 07743, Jena, Germany
| | - Ankita Malik
- Biomolecular Systems Department, Max-Planck-Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany.,Department of Biology, Chemistry and Pharmacy, Free University Berlin, Arnimallee 22, 14195, Berlin, Germany
| | - Peter H Seeberger
- Biomolecular Systems Department, Max-Planck-Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany.,Department of Biology, Chemistry and Pharmacy, Free University Berlin, Arnimallee 22, 14195, Berlin, Germany
| | - Daniel Varón Silva
- Biomolecular Systems Department, Max-Planck-Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany.,Department of Biology, Chemistry and Pharmacy, Free University Berlin, Arnimallee 22, 14195, Berlin, Germany
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14
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Banerjee P, Wehle M, Lipowsky R, Santer M. A molecular dynamics model for glycosylphosphatidyl-inositol anchors: “flop down” or “lollipop”? Phys Chem Chem Phys 2018; 20:29314-29324. [DOI: 10.1039/c8cp04059a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Computational model for GPI anchors tested in DMPC and POPC bilayers. The free anchor rarely occurs as an erected “lollipop-like” conformation, it rather “flops down” onto the bilayer surface. Yet an attached protein (here green fluorescent protein) exhibits extensive orientational flexibility due to the phospho-ethanolamine linker.
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Affiliation(s)
- Pallavi Banerjee
- Department of Theory and Biosystems
- Max Planck Institute for Colloids and Interfaces
- 14424 Potsdam
- Germany
| | - Marko Wehle
- Department of Theory and Biosystems
- Max Planck Institute for Colloids and Interfaces
- 14424 Potsdam
- Germany
| | - Reinhard Lipowsky
- Department of Theory and Biosystems
- Max Planck Institute for Colloids and Interfaces
- 14424 Potsdam
- Germany
| | - Mark Santer
- Department of Theory and Biosystems
- Max Planck Institute for Colloids and Interfaces
- 14424 Potsdam
- Germany
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15
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Sauter J, Grafmüller A. Procedure for Transferable Coarse-Grained Models of Aqueous Polysaccharides. J Chem Theory Comput 2016; 13:223-236. [DOI: 10.1021/acs.jctc.6b00613] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Jörg Sauter
- Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam 14424, Germany
| | - Andrea Grafmüller
- Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam 14424, Germany
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16
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Joosten RP, Lütteke T. Carbohydrate 3D structure validation. Curr Opin Struct Biol 2016; 44:9-17. [PMID: 27816840 DOI: 10.1016/j.sbi.2016.10.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Revised: 10/07/2016] [Accepted: 10/13/2016] [Indexed: 12/11/2022]
Abstract
Glycoproteins and protein-carbohydrate complexes in the worldwide Protein Data Bank (wwPDB) can be an excellent source of information for glycoscientists. Unfortunately, a rather large number of errors and inconsistencies is found in the glycan moieties of these 3D structures. This review illustrates frequent problems of carbohydrate moieties in wwPDB entries, such as nomenclature issues, incorrect N-glycan core structures, missing or erroneous linkages, or poor glycan geometry, and describes the carbohydrate-specific validation tools that are designed to identify such problems. Recommendations how to avoid these issues or how to rectify incorrect structures are also given.
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Affiliation(s)
- Robbie P Joosten
- Department of Biochemistry, Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands
| | - Thomas Lütteke
- Institute of Veterinary Physiology and Biochemistry, Justus-Liebig-University Giessen, Frankfurter Str. 100, 35392 Giessen, Germany.
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17
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Reinhardt A, Wehle M, Geissner A, Crouch EC, Kang Y, Yang Y, Anish C, Santer M, Seeberger PH. Structure binding relationship of human surfactant protein D and various lipopolysaccharide inner core structures. J Struct Biol 2016; 195:387-395. [DOI: 10.1016/j.jsb.2016.06.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 06/23/2016] [Accepted: 06/24/2016] [Indexed: 11/30/2022]
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18
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Sauter J, Grafmüller A. Predicting the Chemical Potential and Osmotic Pressure of Polysaccharide Solutions by Molecular Simulations. J Chem Theory Comput 2016; 12:4375-84. [PMID: 27529356 DOI: 10.1021/acs.jctc.6b00295] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Jörg Sauter
- Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces , 14424 Potsdam, Germany
| | - Andrea Grafmüller
- Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces , 14424 Potsdam, Germany
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19
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Schimka S, Santer S, Mujkić-Ninnemann NM, Bléger D, Hartmann L, Wehle M, Lipowsky R, Santer M. Photosensitive Peptidomimetic for Light-Controlled, Reversible DNA Compaction. Biomacromolecules 2016; 17:1959-68. [DOI: 10.1021/acs.biomac.6b00052] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Selina Schimka
- Institute
of Physics and Astronomy, University of Potsdam, 14476 Potsdam, Germany
- Max Planck Institute
of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Svetlana Santer
- Institute
of Physics and Astronomy, University of Potsdam, 14476 Potsdam, Germany
| | | | - David Bléger
- Humboldt-Universität
zu Berlin, 12489 Berlin, Germany
| | - Laura Hartmann
- Max Planck Institute
of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Marko Wehle
- Theory
and Bio-Systems Group, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Reinhard Lipowsky
- Theory
and Bio-Systems Group, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Mark Santer
- Theory
and Bio-Systems Group, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
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20
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Kang Y, Gohlke U, Engström O, Hamark C, Scheidt T, Kunstmann S, Heinemann U, Widmalm G, Santer M, Barbirz S. Bacteriophage Tailspikes and Bacterial O-Antigens as a Model System to Study Weak-Affinity Protein–Polysaccharide Interactions. J Am Chem Soc 2016; 138:9109-18. [DOI: 10.1021/jacs.6b00240] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Yu Kang
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Ulrich Gohlke
- Max-Delbrück-Centrum für Molekulare Medizin in der Helmholtz-Gemeinschaft, Robert-Rössle-Str. 10, 13125 Berlin, Germany
| | - Olof Engström
- Department
of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106
91 Stockholm, Sweden
| | - Christoffer Hamark
- Department
of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106
91 Stockholm, Sweden
| | - Tom Scheidt
- Physikalische
Biochemie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Sonja Kunstmann
- Physikalische
Biochemie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Udo Heinemann
- Max-Delbrück-Centrum für Molekulare Medizin in der Helmholtz-Gemeinschaft, Robert-Rössle-Str. 10, 13125 Berlin, Germany
- Institut
für Chemie und Biochemie, Freie Universität, Takustr. 6, 14195 Berlin, Germany
| | - Göran Widmalm
- Department
of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106
91 Stockholm, Sweden
| | - Mark Santer
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Stefanie Barbirz
- Physikalische
Biochemie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
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21
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Jo S, Qi Y, Im W. Preferred conformations of N-glycan core pentasaccharide in solution and in glycoproteins. Glycobiology 2015; 26:19-29. [PMID: 26405106 DOI: 10.1093/glycob/cwv083] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 09/14/2015] [Indexed: 11/13/2022] Open
Abstract
N-linked glycans are on protein surfaces and have direct and water/ion-mediated interactions with surrounding amino acids. Such contacts could restrict their conformational freedom compared to the same glycans free in solution. In this work, we have examined the conformational freedom of the N-glycan core pentasaccharide moiety in solution using standard molecular dynamics (MD) simulations as well as temperature replica-exchange MD simulations. Both simulations yield the comparable conformational variability of the pentasaccharide in solution, indicating the convergence of both simulations. The glycoprotein crystal structures are analyzed to compare the conformational freedom of the N-glycan on the protein surface with the simulation result. Surprisingly, the pentasaccharide free in solution shows more restricted conformational variability than the N-glycan on the protein surface. The interactions between the carbohydrate and the protein side chain appear to be responsible for the increased conformational diversity of the N-glycan on the protein surface. Finally, the transfer entropy analysis of the simulation trajectory also reveals an unexpected causality relationship between intramolecular hydrogen bonds and the conformational states in that the hydrogen bonds play a role in maintaining the conformational states rather than driving the change in glycosidic torsional states.
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Affiliation(s)
- Sunhwan Jo
- Leadership Computing Center, Argonne National Laboratory, 9700 Cass Ave Bldg. 240, Argonne, IL 60439, USA
| | - Yifei Qi
- Department of Molecular Biosciences and Center for Computational Biology, The University of Kansas, 2030 Becker Drive, Lawrence, KS 66047, USA
| | - Wonpil Im
- Department of Molecular Biosciences and Center for Computational Biology, The University of Kansas, 2030 Becker Drive, Lawrence, KS 66047, USA
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22
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Lu L, Gao J, Guo Z. Labeling Cell Surface GPIs and GPI-Anchored Proteins through Metabolic Engineering with Artificial Inositol Derivatives. Angew Chem Int Ed Engl 2015; 54:9679-9682. [PMID: 26102235 PMCID: PMC4536913 DOI: 10.1002/anie.201503814] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2015] [Indexed: 11/07/2022]
Abstract
Glycosylphosphatidylinositol (GPI) anchoring of proteins to the cell surface is important for various biological processes, but GPI-anchored proteins are difficult to study. An effective strategy was developed for the metabolic engineering of cell-surface GPIs and GPI-anchored proteins by using inositol derivatives carrying an azido group. The azide-labeled GPIs and GPI-anchored proteins were then tagged with biotin on live cells through a click reaction, which allows further elaboration with streptavidin-conjugated dyes or other molecules. The strategy can be used to label GPI-anchored proteins with various tags for biological studies.
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Affiliation(s)
- Lili Lu
- National Glycoengineering Research Center, Shandong University, 29 Shanda Nan Lu, Jinan 250010 (China)
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202 (the United States)
| | - Jian Gao
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202 (the United States)
| | - Zhongwu Guo
- National Glycoengineering Research Center, Shandong University, 29 Shanda Nan Lu, Jinan 250010 (China)
- Department of Chemistry, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202 (the United States)
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23
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Lu L, Gao J, Guo Z. Labeling Cell Surface GPIs and GPI-Anchored Proteins through Metabolic Engineering with Artificial Inositol Derivatives. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201503814] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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24
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Sauter J, Grafmüller A. Solution Properties of Hemicellulose Polysaccharides with Four Common Carbohydrate Force Fields. J Chem Theory Comput 2015; 11:1765-74. [PMID: 26574386 DOI: 10.1021/ct500924f] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hemicellulose polysaccharides play an important role in the swelling behavior of the primary plant cell wall, and molecular dynamics simulations provide the means of gaining a concise understanding of the interactions of hemicellulose polysaccharides with water. Here, we compare four of the main polysaccharide force fields (CHARMM36 TIP3P, GROMOS56A6(CARBO) SPC, GLYCAM06h TIP3P, and GLYCAM06h TIP5P) for the most abundant hemicellulose backbone components. In particular, we compare aggregation, diffusion coefficients, system density, and investigate the free energy of hydration of saccharides in water. We find that the saccharides show nonphysical aggregation at low concentrations with the GLYCAM06h TIP3P force field, which can be rectified by the use of the TIP5P water model. As a result of the aggregation, GLYCAM06h TIP3P does not lead to reasonable diffusion coefficients whereas the diffusion coefficients, as well as the system density, agrees best with experimental data for the GLYCAM06h TIP5P force field. Overall, GLYCAM06h TIP5P gives good agreement with experimental free energy of hydration data for small saccharides. In addition, the free energy of hydration for short polysaccharides calculated with the GLYCAM06h TIP5P force field is consistent with the radial distribution functions between the polysaccharides and water, the hydration number of the polysaccharides, and the hydrogen bonds formed in the system.
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Affiliation(s)
- Jörg Sauter
- Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces , Potsdam, Germany
| | - Andrea Grafmüller
- Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces , Potsdam, Germany
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25
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New Insights into Lipid Monolayers from Coarse-Grained Simulation Techniques. Biophys J 2014; 107:1038-1039. [DOI: 10.1016/j.bpj.2014.07.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 07/08/2014] [Accepted: 07/15/2014] [Indexed: 11/20/2022] Open
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26
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Brunschweiger A. Report from the Third Annual Symposium of the RIKEN-Max Planck Joint Research Center for Systems Chemical Biology. ACS Chem Biol 2014; 9:1649-52. [PMID: 25123304 DOI: 10.1021/cb500579u] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The third Annual Symposium of the RIKEN-Max Planck Joint Research Center for Systems Chemical Biology was held at Ringberg castle, May 21-24, 2014. At this meeting 45 scientists from Japan and Germany presented the latest results from their research spanning a broad range of topics in chemical biology and glycobiology.
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Affiliation(s)
- Andreas Brunschweiger
- Fakultät
Chemie - Chemische
Biologie, Technische Universität Dortmund, Otto-Hahn-Str.
6, 44227 Dortmund, Germany
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27
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Stefaniu C, Vilotijevic I, Santer M, Brezesinski G, Seeberger PH, Varón Silva D. Versatility of a glycosylphosphatidylinositol fragment in forming highly ordered polymorphs. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:5185-92. [PMID: 24725055 DOI: 10.1021/la500482s] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Glycosylphosphatidylinositols (GPIs) are often attributed with the ability to associate with the organized membrane microdomains. GPI fragment 1 forms a highly ordered subgel-phase structure characterized by ordering of both headgroups and alkyl chains in thin layers. While investigating the driving forces behind the formation of these ordered monolayers, we have studied polymorphism of 1 under different conditions employing surface-sensitive X-ray diffraction methods. Three distinct polymorphs of 1 (I, II, and III) were identified and characterized by grazing incidence X-ray diffraction. Polymorphs II (a condensed monolayer structure) and III (highly ordered subgel phase) coexist on an 8 M urea solution subphase allowing for a detailed thermodynamic and kinetic analysis of the processes leading to the formation of these polymorphs. They are enantiotropic and can be directly interconverted by changes in temperature or lateral surface pressure. As a consequence, polymorph III nuclei of critical size (or larger) could be formed by density fluctuations in a multicomponent system, and they could continue to exist for a period of time even under conditions that would normally not allow for the nucleation of polymorph III. The processes described here could also lead to the formation of patches of highly ordered structures in a disordered environment of a cell membrane suggesting that GPIs may play a role in the formation of such domains.
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Affiliation(s)
- Cristina Stefaniu
- Max Planck Institute of Colloids and Interfaces , Potsdam 14424, Germany
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28
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Hadden JA, French AD, Woods RJ. Effect of microfibril twisting on theoretical powder diffraction patterns of cellulose Iβ. CELLULOSE (LONDON, ENGLAND) 2014; 21:879-884. [PMID: 24729665 PMCID: PMC3979627 DOI: 10.1007/s10570-013-0051-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Previous studies of calculated diffraction patterns for cellulose crystallites suggest that distortions that arise once models have been subjected to MD simulation are the result of both microfibril twisting and changes in unit cell dimensions induced by the empirical force field; to date, it has not been possible to separate the individual contributions of these effects. To provide a better understanding of how twisting manifests in diffraction data, the present study demonstrates a method for generating twisted and linear cellulose structures that can be compared without the bias of dimensional changes, allowing assessment of the impact of twisting alone. Analysis of unit cell dimensions, microfibril volume, hydrogen bond patterns, glycosidic torsion angles, and hydroxymethyl group orientations confirmed that the twisted and linear structures collected with this method were internally consistent, and theoretical powder diffraction patterns for the two were shown to be effectively indistinguishable. These results indicate that differences between calculated patterns for the crystal coordinates and twisted structures from MD simulation can result entirely from changes in unit cell dimensions, and not from microfibril twisting alone. Although powder diffraction patterns for models in the 81-chain size regime were shown to be unaffected by twisting, suggesting that a modest degree of twist is not inconsistent with experimental data, it may be that other diffraction techniques are capable of detecting this structural difference. Until such time as definitive experimental evidence comes to light, the results of this study suggest that both twisted and linear microfibrils may represent an appropriate model for cellulose Iβ.
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Affiliation(s)
- Jodi A. Hadden
- Complex Carbohydrate Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602
| | - Alfred D. French
- Southern Regional Research Center, U.S. Department of Agriculture, 1100 Robert E. Lee Boulevard, New Orleans, LA 70124
| | - Robert J. Woods
- Complex Carbohydrate Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602
- School of Chemistry, National University of Ireland, Galway, University Road, Galway, Ireland
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29
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Kang Y, Barbirz S, Lipowsky R, Santer M. Conformational Diversity of O-Antigen Polysaccharides of the Gram-Negative Bacterium Shigella flexneri Serotype Y. J Phys Chem B 2014; 118:2523-34. [DOI: 10.1021/jp4111713] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Yu Kang
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Stefanie Barbirz
- Physikalische
Biochemie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
| | - Reinhard Lipowsky
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Mark Santer
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
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30
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Stefaniu C, Vilotijevic I, Brezesinski G, Seeberger PH, Varón Silva D. A comparative structural study in monolayers of GPI fragments and their binary mixtures. Phys Chem Chem Phys 2014; 16:9259-65. [PMID: 24714927 DOI: 10.1039/c4cp00567h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- C Stefaniu
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany.
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31
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Wood NT, Fadda E, Davis R, Grant OC, Martin JC, Woods RJ, Travers SA. The influence of N-linked glycans on the molecular dynamics of the HIV-1 gp120 V3 loop. PLoS One 2013; 8:e80301. [PMID: 24303005 PMCID: PMC3841175 DOI: 10.1371/journal.pone.0080301] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 10/11/2013] [Indexed: 02/07/2023] Open
Abstract
N-linked glycans attached to specific amino acids of the gp120 envelope trimer of a HIV virion can modulate the binding affinity of gp120 to CD4, influence coreceptor tropism, and play an important role in neutralising antibody responses. Because of the challenges associated with crystallising fully glycosylated proteins, most structural investigations have focused on describing the features of a non-glycosylated HIV-1 gp120 protein. Here, we use a computational approach to determine the influence of N-linked glycans on the dynamics of the HIV-1 gp120 protein and, in particular, the V3 loop. We compare the conformational dynamics of a non-glycosylated gp120 structure to that of two glycosylated gp120 structures, one with a single, and a second with five, covalently linked high-mannose glycans. Our findings provide a clear illustration of the significant effect that N-linked glycosylation has on the temporal and spatial properties of the underlying protein structure. We find that glycans surrounding the V3 loop modulate its dynamics, conferring to the loop a marked propensity towards a more narrow conformation relative to its non-glycosylated counterpart. The conformational effect on the V3 loop provides further support for the suggestion that N-linked glycosylation plays a role in determining HIV-1 coreceptor tropism.
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Affiliation(s)
- Natasha T. Wood
- South African National Bioinformatics Institute, South African Medical Research Council Bioinformatics Unit, University of the Western Cape, Cape Town, South Africa
| | - Elisa Fadda
- Department of Chemistry, National University of Ireland, Maynooth, Maynooth, Ireland
| | - Robert Davis
- Complex Carbohydrate Research Centre, University of Georgia, Athens, Georgia, United States of America
| | - Oliver C. Grant
- School of Chemistry, National University of Ireland, Galway, Galway, Ireland
| | - Joanne C. Martin
- School of Chemistry, National University of Ireland, Galway, Galway, Ireland
| | - Robert J. Woods
- Complex Carbohydrate Research Centre, University of Georgia, Athens, Georgia, United States of America
- School of Chemistry, National University of Ireland, Galway, Galway, Ireland
| | - Simon A. Travers
- South African National Bioinformatics Institute, South African Medical Research Council Bioinformatics Unit, University of the Western Cape, Cape Town, South Africa
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32
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Recent progress in synthetic and biological studies of GPI anchors and GPI-anchored proteins. Curr Opin Chem Biol 2013; 17:1006-13. [PMID: 24128440 DOI: 10.1016/j.cbpa.2013.09.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Revised: 09/22/2013] [Accepted: 09/24/2013] [Indexed: 10/26/2022]
Abstract
Covalent attachment of glycosylphosphatidylinositols (GPIs) to the protein C-terminus is one of the most common posttranslational modifications in eukaryotic cells. In addition to anchoring surface proteins to the cell membrane, GPIs also have many other important biological functions, determined by their unique structure and property. This account has reviewed the recent progress made in disclosing GPI and GPI-anchored protein biosynthesis, in the chemical and chemoenzymatic synthesis of GPIs and GPI-anchored proteins, and in understanding the conformation, organization, and distribution of GPIs in the lipid membrane.
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