Rapid Flip-Flop of Phospholipids in Endoplasmic Reticulum Membranes Studied by a Stopped-Flow Approach

Marx, Uwe; Laßmann, G.; Holzhütter, Hermann‐Georg; Wüstner, Daniel; Müller, Peter; Höhlig, Astrid; Kubelt, Janek; Herrmann, Andreas

doi:10.1016/s0006-3495(00)76807-x

Cited by 85 publications

(99 citation statements)

References 35 publications

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“…To prevent such a loss of possible hydrophobic binding sites, the pH of respective samples of BHA and of virions was lowered in the presence of SL-LPC. From our previous study (42), we surmise that the half-time of binding of SL-LPC to hydrophobic sites should be in the order of Յ5 s. This fast binding of SL-LPC allows to compete efficiently for hydrophobic binding sites. Therefore, we conclude that the low binding of SL-LPC to HA is not because of a loss or shielding but because of the absence of hydrophobic sites with high affinity for SL-LPC.…”

Section: Interaction Of Sl-lpc With Intact and Bromelain-treated Virumentioning

confidence: 94%

Lysolipids Do Not Inhibit Influenza Virus Fusion by Interaction with Hemagglutinin

Baljinnyam¹,

Schroth‐Diez²,

Korte

et al. 2002

Journal of Biological Chemistry

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The interaction of a spin-labeled lysophosphatidylcholine analog with intact and bromelain-treated influenza viruses as well as with the bromelain-solubilized hemagglutinin ectodomain has been studied. The inhibition of fusion of influenza viruses with erythrocytes by the lysophosphatidylcholine analog was similar to that observed for non-labeled lysophosphatidylcholine. Only a weak interaction of the lysophosphatidylcholine analog with the hemagglutinin ectodomain was observed even upon triggering the conformational change of the ectodomain at a low pH. A significant interaction of spin-labeled lysophosphatidylcholine with the hemagglutinin ectodomain of intact viruses was observed neither at neutral nor at low pH, whereas a strong interaction of the lipid analog with the viral lipid bilayer was evident. We suggest that the high number of lipid binding sites of the virus bilayer and their affinity compete efficiently with binding sites of the hemagglutinin ectodomain. We conclude that the inhibition of influenza virus fusion by lysolipids is not mediated by binding to the hemagglutinin ectodomain, preventing its interaction with the target membrane. The results unambiguously argue for an inhibition mechanism based on the action of lysolipid inserted into the lipid bilayer.

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Section: Interaction Of Sl-lpc With Intact and Bromelain-treated Virumentioning

confidence: 94%

Lysolipids Do Not Inhibit Influenza Virus Fusion by Interaction with Hemagglutinin

Baljinnyam¹,

Schroth‐Diez²,

Korte

et al. 2002

Journal of Biological Chemistry

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“…6c). Considering rapid PE flip-flop between inner/outer membrane leaflets [26,56],~50% of PE (~13.5 amol/CV) would be in the contacting monolayer; saturation of binding and inhibition of function was thus expected at 1 nM cinnamycin if PE is a critical fusion component. Similarly, D609 decreased PE by~9 amol/CV, causing~23% inhibition of fusion extent.…”

Section: Critical Roles For Chol In Triggered Membrane Fusionmentioning

confidence: 99%

A new approach to the molecular analysis of docking, priming, and regulated membrane fusion

Rogasevskaia

Coorssen

2011

J Chem Biol

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Studies using isolated sea urchin cortical vesicles have proven invaluable in dissecting mechanisms of Ca 2+ -triggered membrane fusion. However, only acute molecular manipulations are possible in vitro. Here, using selective pharmacological manipulations of sea urchin eggs ex vivo, we test the hypothesis that specific lipidic components of the membrane matrix selectively affect defined late stages of exocytosis, particularly the Ca 2+ -triggered steps of fast membrane fusion. Egg treatments with cholesterol-lowering drugs resulted in the inhibition of vesicle fusion. Exogenous cholesterol recovered fusion extent and efficiency in cholesterol-depleted membranes; α-tocopherol, a structurally dissimilar curvature analogue, selectively restored fusion extent. Inhibition of phospholipase C reduced vesicle phosphatidylethanolamine and suppressed both the extent and kinetics of fusion. Although phosphatidylinositol-3-kinase inhibition altered levels of polyphosphoinositide species and reduced all fusion parameters, sequestering polyphosphoinositides selectively inhibited fusion kinetics. Thus, cholesterol and phosphatidylethanolamine play direct roles in the fusion pathway, contributing negative curvature. Cholesterol also organizes the physiological fusion site, defining fusion efficiency. A selective influence of phosphatidylethanolamine on fusion kinetics sheds light on the local microdomain structure at the site of docking/fusion. Polyphosphoinositides have modulatory upstream roles in priming: alterations in specific polyphosphoinositides likely represent the terminal priming steps defining fully docked, release-ready vesicles. Thus, this pharmacological approach has the potential to be a robust high-throughput platform to identify molecular components of the physiological fusion machine critical to docking, priming, and triggered fusion.

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“…Translocation was assessed using an on-line fluorescence BSA back-exchange assay as described previously (43), and the analogues of PE and PC behaved similarly in this assay.…”

Section: Characterization Of Phospholipid Transbilayer Movement In Bimentioning

confidence: 99%

Transbilayer Movement of Phospholipids in Biogenic Membranes

et al. 2004

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Biogenic membranes contain the enzymes that synthesize the cell's membrane lipids, of which the phospholipids are the most widespread throughout nature. Being synthesized at and inserted into the cytoplasmic leaflet of biogenic membranes, the phospholipids must migrate to the opposite leaflet to ensure balanced growth of the membrane. In this review, the current knowledge of transbilayer movement of phospholipids in biogenic membranes is summarized and the available data are compared to what is known about lipid translocation in other membranes. On the basis of this, a mechanism is proposed, in which phospholipid translocation in biogenic membranes is mediated via membrane-spanning segments of a subset of proteins, characterized by a small number of transmembrane helices. We speculate that proteins of this subset facilitate lipid translocation via the protein-lipid interface, because they display more dynamic behavior and engage in less stable protein-lipid interactions than larger membrane proteins. Structure, Function, and Assembly of Biomembranes

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Rapid Flip-Flop of Phospholipids in Endoplasmic Reticulum Membranes Studied by a Stopped-Flow Approach

Cited by 85 publications

References 35 publications

Lysolipids Do Not Inhibit Influenza Virus Fusion by Interaction with Hemagglutinin

Lysolipids Do Not Inhibit Influenza Virus Fusion by Interaction with Hemagglutinin

A new approach to the molecular analysis of docking, priming, and regulated membrane fusion

Transbilayer Movement of Phospholipids in Biogenic Membranes

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