Ghasemitarei, M. | Search bioRxiv

bioRxiv2026

Impact of viral membrane oxidation on SARS-CoV-2 spike protein transmembrane anchoring stability

Reactive oxygen species generated during inflammation can oxidize viral envelope lipids, with outcomes ranging from modulated infectivity to viral inactivation. For SARS-CoV-2, the molecular mechanisms by which membrane lipid oxidation influences spike protein anchoring remain poorly understood. We use all-atom molecular dynamics (MD) simulations to quantify how graded oxidation of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) affects the anchoring of the SARS-CoV-2 spike transmembrane (TM) region in an endoplasmic-reticulum-Golgi intermediate compartment (ERGIC)-like multicomponent membrane. Viral envelopes containing 0, 25, 50, 75, and 100% oxidized POPC (PoxnoPC) corresponding to 0 - 55% oxidation of all PO-type phospholipids were simulated with the spike TM helix and cytoplasmic tail embedded in a POPC/POPE/POPI/POPS/cholesterol mixture. Steered MD and umbrella sampling were used to calculate the potential of mean force (PMF) for extracting the TM+CT region along the membrane normal. Partial oxidation (25 - 75% POPC) produced reductions in the detachment barrier that were not statistically distinguishable from the native system within the sampling uncertainty, whereas full POPC oxidation lowered the anchoring free energy by about 23% (from 606 {+/-} 39 to 464 {+/-} 38 kJ mol-1), indicating that oxidation of roughly half of the glycerophospholipids can measurably weaken spike-membrane coupling. Despite this reduction, the remaining barrier (about 180kBT ) is still large, suggesting that oxidation alone may be insufficient for spontaneous spike detachment and likely acts synergistically with mechanical forces during fusion or immune engagement. Analysis of acyl-chain order parameters, area per lipid, membrane thickness, number-density profiles, and lateral lipid clustering reveals that POPC peroxidation decreases lipid order, thins and softens the bilayer, and disrupts cholesterol-stabilized clusters that refer to large cooperative lipid assemblies (>10 lipids) identified via RDF-based clustering. These oxidation-induced changes reduce hydrophobic matching around the TM helix and facilitate its extraction from the viral envelope. Our results provide a mechanistic link between lipid peroxidation, membrane nanostructure, and spike anchoring, supporting lipid oxidation for example during cold atmospheric plasma or ozone treatment as a physically grounded contributing antiviral mechanism against SARS-CoV-2.

biochemistry↗

bioRxiv2024

Effect of cysteine oxidation in SARS-CoV-2 Spike protein on its conformational changes: insights from atomistic simulations

This study investigates the effect of cysteine (Cys) oxidation on the conformational changes of the SARS-CoV-2 Spike (S) protein, a critical factor in viral attachment and entry into host cells. Using targeted molecular dynamics (TMD) simulations, we explore the conformational transitions between the down (inaccessible) and up (accessible) states of the SARS-CoV-2 S protein in both its native and oxidized forms. Our findings reveal that oxidation significantly increases the energy barrier for these transitions, as indicated by the work required to move from the down to the up conformation and vice versa. Specifically, in the oxidized system compared to the native system, the energy required to transition from the down to the up conformation increases by approximately 131 {+/-} 1 kJ.mol-1, while the energy required for the reverse transition increases by about 223 {+/-} 6 kJ.mol-1. This is due to the stabilizing effect of oxidation on the conformation of the SARS-CoV-2 S protein. Analysis of hydrogen bond and salt bridge formation before and after oxidation provides additional insights into the stabilization mechanisms, showing an increase in salt bridge formation that contributes to conformational stabilization. These results underscore the potential of targeting translational modifications to hamper viral entry or enhance susceptibility to neutralization, offering a novel perspective for antiviral strategy development against SARS-CoV-2. This study adds important knowledge to the field of viral protein dynamics and highlights the critical role of structural and computational biology in uncovering new therapeutic avenues.

biophysics↗