Browsing by Author "Matsarskaia, O"

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    “Invisible” detergents enable a reliable determination of solution structures of native photosystems by small-angle neutron scattering
    (ACS Publications, 2022-04-06) Golub, M; Gätcke, J; Subramanian, S; Kölsch, A; Darwish, TA; Feoktystov, A; Matsarskaia, O; Martel, A; Porcar, L; Zouni, A; Pieper, J
    Photosystems I (PSI) and II (PSII) are pigment–protein complexes capable of performing the light-induced charge separation necessary to convert solar energy into a biochemically storable form, an essential step in photosynthesis. Small-angle neutron scattering (SANS) is unique in providing structural information on PSI and PSII in solution under nearly physiological conditions without the need for crystallization or temperature decrease. We show that the reliability of the solution structure critically depends on proper contrast matching of the detergent belt surrounding the protein. Especially, specifically deuterated (“invisible”) detergents are shown to be properly matched out in SANS experiments by a direct, quantitative comparison with conventional matching strategies. In contrast, protonated detergents necessarily exhibit incomplete matching so that related SANS results systematically overestimate the size of the membrane protein under study. While the solution structures obtained are close to corresponding high-resolution structures, we show that temperature and solution state lead to individual structural differences compared with high-resolution structures. We attribute these differences to the presence of a manifold of conformational substates accessible by protein dynamics under physiological conditions. © 2022 American Chemical Society
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    Strikingly 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, NR
    Coronavirus 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.