Browsing by Author "Haertlein, M"
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- ItemApolipoprotein E binding drives structural and compositional rearrangement of mRNA-containing lipid nanoparticles(American Chemical Society (ACS), 2021-03-23) Sebastiani, F; Yanez Arteta, M; Lerche, M; Porcar, L; Lang, C; Bragg, RA; Elmore, CS; Krishnamurthy, VR; Russell, RA; Darwish, TA; Pichler, H; Waldie, S; Moulin, M; Haertlein, M; Forsyth, VT; Lindfors, L; Cárdenas, MEmerging therapeutic treatments based on the production of proteins by delivering mRNA have become increasingly important in recent times. While lipid nanoparticles (LNPs) are approved vehicles for small interfering RNA delivery, there are still challenges to use this formulation for mRNA delivery. LNPs are typically a mixture of a cationic lipid, distearoylphosphatidylcholine (DSPC), cholesterol, and a PEG-lipid. The structural characterization of mRNA-containing LNPs (mRNA-LNPs) is crucial for a full understanding of the way in which they function, but this information alone is not enough to predict their fate upon entering the bloodstream. The biodistribution and cellular uptake of LNPs are affected by their surface composition as well as by the extracellular proteins present at the site of LNP administration, e.g., apolipoproteinE (ApoE). ApoE, being responsible for fat transport in the body, plays a key role in the LNP's plasma circulation time. In this work, we use small-angle neutron scattering, together with selective lipid, cholesterol, and solvent deuteration, to elucidate the structure of the LNP and the distribution of the lipid components in the absence and the presence of ApoE. While DSPC and cholesterol are found to be enriched at the surface of the LNPs in buffer, binding of ApoE induces a redistribution of the lipids at the shell and the core, which also impacts the LNP internal structure, causing release of mRNA. The rearrangement of LNP components upon ApoE incubation is discussed in terms of potential relevance to LNP endosomal escape. © 2021 American Chemical Society. Open Access. This publication is licensed under CC-BY 4.0.
- ItemBilayer-mediated clustering and functional interaction of MscL channels(Cell Press, 2011-03-02) Grage, SL; Keleshian, AM; Turdzeladze, T; Battle, AR; Tay, WC; May, RP; Holt, SA; Contera, SA; Haertlein, M; Moulin, M; Pal, P; Rohde, PR; Forsyth, VT; Watts, A; Huang, KC; Ulrich, AS; Martinac, BMechanosensitive channels allow bacteria to respond to osmotic stress by opening a nanometer-sized pore in the cellular membrane. Although the underlying mechanism has been thoroughly studied on the basis of individual channels, the behavior of channel ensembles has yet to be elucidated. This work reveals that mechanosensitive channels of large conductance (MscL) exhibit a tendency to spatially cluster, and demonstrates the functional relevance of clustering. We evaluated the spatial distribution of channels in a lipid bilayer using patch-clamp electrophysiology, fluorescence and atomic force microscopy, and neutron scattering and reflection techniques, coupled with mathematical modeling of the mechanics of a membrane crowded with proteins. The results indicate that MscL forms clusters under a wide range of conditions. MscL is closely packed within each cluster but is still active and mechanosensitive. However, the channel activity is modulated by the presence of neighboring proteins, indicating membrane-mediated protein-protein interactions. Collectively, these results suggest that MscL self-assembly into channel clusters plays an osmoregulatory functional role in the membrane.© 2011, Cell Press
- ItemDynamical coupling of intrinsically disordered proteins and their hydration water: comparison with folded soluble and membrane proteins(Cell Press, 2012-07-03) Gallat, FX; Laganowsky, A; Wood, K; Gabel, F; van Eijck, L; Wuttke, J; Moulin, M; Haertlein, M; Eisenberg, D; Colletier, JP; Zaccai, G; Weik, MHydration water is vital for various macromolecular biological activities, such as specific ligand recognition, enzyme activity, response to receptor binding, and energy transduction. Without hydration water, proteins would not fold correctly and would lack the conformational flexibility that animates their three-dimensional structures. Motions in globular, soluble proteins are thought to be governed to a certain extent by hydration-water dynamics, yet it is not known whether this relationship holds true for other protein classes in general and whether, in turn, the structural nature of a protein also influences water motions. Here, we provide insight into the coupling between hydration-water dynamics and atomic motions in intrinsically disordered proteins (IDP), a largely unexplored class of proteins that, in contrast to folded proteins, lack a well-defined three-dimensional structure. We investigated the human IDP tau, which is involved in the pathogenic processes accompanying Alzheimer disease. Combining neutron scattering and protein perdeuteration, we found similar atomic mean-square displacements over a large temperature range for the tau protein and its hydration water, indicating intimate coupling between them. This is in contrast to the behavior of folded proteins of similar molecular weight, such as the globular, soluble maltose-binding protein and the membrane protein bacteriorhodopsin, which display moderate to weak coupling, respectively. The extracted mean square displacements also reveal a greater motional flexibility of IDP compared with globular, folded proteins and more restricted water motions on the IDP surface. The results provide evidence that protein and hydration-water motions mutually affect and shape each other, and that there is a gradient of coupling across different protein classes that may play a functional role in macromolecular activity in a cellular context. © 2012, Cell Press.
- ItemHigh-density lipoprotein function is modulated by the SARS-CoV-2 spike protein in a lipid-type dependent manner(Elsevier B. V., 2023-09) Correa, YB; Del Giuduce, R; Waldie, S; Thépaut, M; Gerelli, Y; Moulin, M; Delauney, C; Fieschi, F; Haertlein, M; Le Brun, AP; Forsyth, VT; Moir, M; Russell, RA; Darwish, TA; Brinck, J; Wodaje, T; Jansen, M; Martín, C; Roosen-Runge, F; Cárdenas, M; Micciulla, S; Pichler, HThere is a close relationship between the SARS-CoV-2 virus and lipoproteins, in particular high-density lipoprotein (HDL). The severity of the coronavirus disease 2019 (COVID-19) is inversely correlated with HDL plasma levels. It is known that the SARS-CoV-2 spike (S) protein binds the HDL particle, probably depleting it of lipids and altering HDL function. Based on neutron reflectometry (NR) and the ability of HDL to efflux cholesterol from macrophages, we confirm these observations and further identify the preference of the S protein for specific lipids and the consequent effects on HDL function on lipid exchange ability. Moreover, the effect of the S protein on HDL function differs depending on the individuals lipid serum profile. Contrasting trends were observed for individuals presenting low triglycerides/high cholesterol serum levels (LTHC) compared to high triglycerides/high cholesterol (HTHC) or low triglycerides/low cholesterol serum levels (LTLC). Collectively, these results suggest that the S protein interacts with the HDL particle and, depending on the lipid profile of the infected individual, it impairs its function during COVID-19 infection, causing an imbalance in lipid metabolism. © Crown Copyright 2023. Published by Elsevier Inc. Open Access - CC BY licence 4.0.
- ItemInvestigation on the relationship between lipid composition and structure in model membranes composed of extracted natural phospholipids(Elsevier B. V., 2023-01-11) Santamaria, A; Batchu, KC; Fragneto, G; Laux, V; Haertlein, M; Darwish, TA; Russell, RA; Zaccai, NR; Guzmán, E; Maestro, AHypothesis Unravelling the structural diversity of cellular membranes is a paramount challenge in life sciences. In particular, lipid composition affects the membrane collective behaviour, and its interactions with other biological molecules. Experiments Here, the relationship between membrane composition and resultant structural features was investigated by surface pressure-area isotherms, Brewster angle microscopy and neutron reflectometry on in vitro membrane models of the mammalian plasma and endoplasmic-reticulum-Golgi intermediate compartment membranes in the form of Langmuir monolayers. Natural extracted yeast lipids were used because, unlike synthetic lipids, the acyl chain saturation pattern of yeast and mammalian lipids are similar. Findings The structure of the model membranes, orthogonal to the plane of the membrane, as well as their lateral packing, were found to depend strongly on their specific composition, with cholesterol having a major influence on the in-plane morphology, yielding a coexistence of liquid-order and liquid-disorder phases. © 2023 Elsevier B.V.
- ItemNew sources and instrumentation for neutrons in biology(Elsevier, 2008-04-18) Teixeira, SCM; Zaccai, G; Ankner, J; Bellissent-Funel, MC; Bewley, RI; Blakeley, MP; Callow, P; Coates, L; Dahint, R; Dalgliesh, R; Dencher, NA; Forsyth, VT; Fragneto, G; Frick, B; Gilles, R; Gutberlet, T; Haertlein, M; Hauß, T; Häußler, W; Heller, WT; Herwig, K; Holderer, O; Juranyi, F; Kampmann, R; Knott, RB; Krueger, S; Langan, P; Lechner, RE; Lynn, GW; Majkrzak, CF; May, RP; Meilleur, F; Mo, Y; Mortensen, K; Myles, DAA; Natali, F; Neylon, C; Niimura, N; Ollivier, J; Ostermann, A; Peters, J; Pieper, J; Rühm, A; Schwahn, D; Shibata, K; Soper, AK; Strässle, T; Suzuki, J; Tanaka, I; Tehei, M; Timmins, P; Torikai, N; Unruh, T; Urban, V; Vavrin, R; Weiss, KNeutron radiation offers significant advantages for the study of biological molecular structure and dynamics. A broad and significant effort towards instrumental and methodological development to facilitate biology experiments at neutron sources worldwide is reviewed. © 2008, Elsevier Ltd.
- ItemProtein surface and core dynamics show concerted hydration-dependent activation(Wiley-V C H Verlag GMBH, 2013-01-01) Wood, K; Gallat, FX; Otten, R; van Heel, AJ; Lethier, M; van Eijck, L; Moulin, M; Haertlein, M; Weik, M; Mulder, FAABy specifically labeling leucine/valine methyl groups and lysine side chains “inside” and “outside” dynamics of proteins on the nanosecond timescale are compared using neutron scattering (see picture). Surprisingly, both groups display similar dynamics as a function of temperature, and the buried hydrophobic core is sensitive to hydration and undergoes a dynamical transition. © 2013, Wiley-VCH Verlag GmbH & Co. KGaA
- ItemStrikingly different roles of SARS-CoV‑2 fusion peptides uncovered by neutron scattering(American Chemical Society (ACS), 2022-02-14) Santamaria, A; Batchu, KC; Matsarskaia, O; Prévost, SF; Russo, D; Natali, F; Seydel, T; Hoffmann, I; Laux, V; Haertlein, M; Darwish, TA; Russell, RA; Corucci, G; Fragneto, G; Maestro, A; Zaccai, NRCoronavirus disease-2019 (COVID-19), a potentially lethal respiratory illness caused by the coronavirus SARS-CoV-2, emerged in the end of 2019 and has since spread aggressively across the globe. A thorough understanding of the molecular mechanisms of cellular infection by coronaviruses is therefore of utmost importance. A critical stage in infection is the fusion between viral and host membranes. Here, we present a detailed investigation of the role of selected SARS-CoV-2 Spike fusion peptides, and the influence of calcium and cholesterol, in this fusion process. Structural information from specular neutron reflectometry and small angle neutron scattering, complemented by dynamics information from quasi-elastic and spin-echo neutron spectroscopy, revealed strikingly different functions encoded in the Spike fusion domain. Calcium drives the N-terminal of the Spike fusion domain to fully cross the host plasma membrane. Removing calcium, however, reorients the peptide back to the lipid leaflet closest to the virus, leading to significant changes in lipid fluidity and rigidity. In conjunction with other regions of the fusion domain, which are also positioned to bridge and dehydrate viral and host membranes, the molecular events leading to cell entry by SARS-CoV-2 are proposed. © 2022 The Authors. Published by American Chemical Society. This publication is licensed under CC-BY-NC-ND 4.0.