Tag Archive for: plasma membrane

Publication on AWSensors technology

Variant-Specific Interactions at the Plasma Membrane: Heparan Sulfate’s Impact on SARS-CoV-2 Binding Kinetics

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Authors: Dario Valter Conca, Fouzia Bano, Małgorzata Graul, Julius von Wirén, Lauriane Scherrer, Hudson Pace, Himanshu Sharma, Justas Svirelis, Konrad Thorsteinsson, Andreas Dahlin, and Marta Bally

Journal: Analytical Chemistry

Abstract: The spread of SARS-CoV-2 led to the emergence of several variants of concern (VOCs). The spike glycoprotein, responsible for engaging the viral receptor, exhibits the highest density of mutations, suggesting an ongoing evolution to optimize viral entry. This study characterizes the bond formed by virion mimics carrying the SARS-CoV-2 spike protein and the plasma membrane of host cells in the early stages of virus entry. Contrary to the traditional analysis of isolated ligand-receptor pairs, we utilized well-defined biomimetic models and biochemical and biophysical techniques to characterize the multivalent interaction of VOCs with the complex cell membrane. We observed an overall increase in the binding affinity for newer VOCs. By progressively reducing the system complexity, we identify heparan sulfate (HS) as a main driver of this variation, with a 10-fold increase in affinity for Omicron BA.1 over that of the original strain. These results demonstrate the essential role of coreceptors, particularly HS, in the modulation of SARS-CoV-2 infection and highlight the importance of multiscale biophysical and biochemical assays that account for membrane complexity to fully characterize and understand the role of molecular components and their synergy in viral attachment and entry.

The full article can be accessed here.

Publication on AWSensors technology

Lipid packing frustration in the outer leaflet of the plasma membrane prevents scission of caveolae

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Authors: Elin Larsson, Aleksei Kabedev, Hudson Pace, Jakob Lindwall, Fouzia Bano, Robert G Parton, Christel A. S. Bergstrom, Ingela Parmryd, Marta Bally, Richard Lundmark

Journal: bioRxiv

Abstract: Lipid packing is a fundamental characteristic of bilayer membranes. It affects all membrane-associated processes ranging from curvature generation to membrane fission. Yet, we lack detailed, mechanistic understanding of how lipid packing directly affects these processes in cellular membranes. Here, we address this by focusing on caveolae, small Ω-shaped invaginations of the plasma membrane which serve as key regulators of cellular lipid sorting and mechano-responses. In addition to caveolae coat proteins, the lipid membrane is a core component of caveolae that critically impacts both the biogenesis, morphology and stability of such membrane invaginations. We show that the small compound Dyngo-4a inserts into the membrane, resulting in a dramatic dynamin-independent inhibition of caveola scission. Analysis of model membranes in combination with molecular dynamics simulations revealed that a substantial amount of Dyngo-4a was inserted and positioned at the level of cholesterol in the bilayer. Dyngo-4a-treatment resulted in decreased lipid packing in the outer leaflet of the plasma membrane preventing scission without affecting caveola morphology, caveolae- associated proteins, or the overall membrane stiffness. Artificially increasing plasma membrane cholesterol levels was found to counteract the block in caveola scission caused by Dyngo-4a-mediated lipid packing frustration. Therefore, we propose that the packing of cholesterol in the outer leaflet of the plasma membrane critically controls the confinement of caveolae to the plasma membrane.

The full article can be accessed here.