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Tick-borne encephalitis virus is an enveloped, pathogenic, RNA virus in the family Flaviviridae, genus Flavivirus. Viral particles are formed when the nucleocapsid, consisting of an RNA genome and multiple copies of the capsid protein, buds through the endoplasmic reticulum membrane and acquires the viral envelope and the associated proteins. The coordination of the nucleocapsid components to the sites of assembly and budding are poorly understood. Here, we investigate the interactions of the wild-type and truncated capsid proteins with membranes with biophysical methods and model membrane systems. We show that capsid protein initially binds membranes via electrostatic interactions with negatively-charged lipids, which is followed by membrane insertion. Additionally, we show that membrane-bound capsid protein can recruit viral genomic RNA. We confirm the biological relevance of the biophysical findings by using mass spectrometry to show that purified virions contain negatively-charged lipids. Our results suggest that nucleocapsid assembly is coordinated by negatively-charged membrane patches on the endoplasmic reticulum and that the capsid protein mediates direct contacts between the nucleocapsid and the membrane., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 Pulkkinen et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Objective: To assess survival outcomes with the intervention of an interprofessional mobilization program for patients with COVID-19 who were receiving venovenous extracorporeal membrane oxygenation (VV-ECMO)., Design: Preintervention and postintervention retrospective cohort study., Methods: Survival outcomes of nonmobilized, adult patients (n = 16) with COVID-19 who were receiving VV-ECMO (May 2020 through December 2020) were compared with those of 26 patients who received a mobility care plan (January 2021 through November 2021). In the preintervention group, full sedation and paralysis were used. In the postintervention group, an early mobilization strategy involving interprofessional collaboration was introduced., Results: The postintervention group had improved survival (73.1% vs 43.8%; P < .04); fewer days of receiving paralytics, fentanyl, and midazolam (P < .01 for all); but more days of dexmedetomidine, morphine, and ketamine administration (P < .01 for all). Concomitantly, more patients in the postintervention cohort received oral or transdermal analgesics, oral anxiolytics, and oral antipsychotics (P < .01 for all), and also required more VV-ECMO cannula adjustments (P = .03)., Conclusion: Early mobilization of patients with COVID-19 who were receiving VV-ECMO improved survival rates but led to more cannula adjustments., (©2022 American Association of Critical-Care Nurses.)

Caveolae are small plasma membrane invaginations, important for control of membrane tension, signaling cascades, and lipid sorting. The caveola coat protein Cavin1 is essential for shaping such high curvature membrane structures. Yet, a mechanistic understanding of how Cavin1 assembles at the membrane interface is lacking. Here, we used model membranes combined with biophysical dissection and computational modeling to show that Cavin1 inserts into membranes. We establish that initial phosphatidylinositol (4, 5) bisphosphate [PI(4,5)P 2 ]-dependent membrane adsorption of the trimeric helical region 1 (HR1) of Cavin1 mediates the subsequent partial separation and membrane insertion of the individual helices. Insertion kinetics of HR1 is further enhanced by the presence of flanking negatively charged disordered regions, which was found important for the coassembly of Cavin1 with Caveolin1 in living cells. We propose that this intricate mechanism potentiates membrane curvature generation and facilitates dynamic rounds of assembly and disassembly of Cavin1 at the membrane.

The α-pore-forming toxins (α-PFTs) from pathogenic bacteria damage host cell membranes by pore formation. We demonstrate a remarkable, hitherto unknown mechanism by an α-PFT protein from Vibrio cholerae . As part of the MakA/B/E tripartite toxin, MakA is involved in membrane pore formation similar to other α-PFTs. In contrast, MakA in isolation induces tube-like structures in acidic endosomal compartments of epithelial cells in vitro. The present study unravels the dynamics of tubular growth, which occurs in a pH-, lipid-, and concentration-dependent manner. Within acidified organelle lumens or when incubated with cells in acidic media, MakA forms oligomers and remodels membranes into high-curvature tubes leading to loss of membrane integrity. A 3.7 Å cryo-electron microscopy structure of MakA filaments reveals a unique protein-lipid superstructure. MakA forms a pinecone-like spiral with a central cavity and a thin annular lipid bilayer embedded between the MakA transmembrane helices in its active α-PFT conformation. Our study provides insights into a novel tubulation mechanism of an α-PFT protein and a new mode of action by a secreted bacterial toxin., Competing Interests: AN, KP, BU, SW S.N.W., B.E.U., A.N., and K.P. wish to make the disclosure that we are named inventors in a PCT application (Vibrio cholerae protein for use against cancer) published under No. WO 2021/071419. This does not alter our adherence to eLife policies on sharing data and materials, AB, HP, AA, ET, JÅ, NZ, SM, GG, AS, MB, JB No competing interests declared, (© 2022, Nadeem et al.)