Inhibition of Membrane Fusion by Lysophosphatidylcholine

Abstract

The ability of lysophosphatidylcholine to inhibit membrane fusion at subsolubilizing concentrations (between 1 and 9 mol % with respect to the membrane lipids) was examined. Fusion between N-methyldioleoylphosphatidylethanolamine (DOPE) large unilamellar vesicles (LUV) and fusion between Sendai virus and N-methyl-DOPE LUV were measured. A contents mixing fusion assay was used for LUV fusion (ANTS/DPX), and a lipid mixing assay (octadecylrhodamine B) was used for the virus fusion experiments. Lysophosphatidylcholine was effective at inhibiting both LUV fusion and Sendai virus/LUV fusion. Lysophosphatidylcholine also inhibited leakage from N-methyl-DOPE LUV, 31P nuclear magnetic resonance data were obtained of N-methyl-DOPE in the presence of lysophosphatidylcholine. Lysophosphatidylcholine stabilized the lamellar phase and reduced the incidence of nonlamellar structures at all temperatures. The destabilization of nonlamellar structures with a negative radius of curvature may be a mechanism for inhibition of fusion by lysophosphatidylcholine in these systems.

5-(Perylen-3-yl)Ethynyl-arabino-Uridine (aUY11), an Arabino-Based Rigid Amphipathic Fusion Inhibitor, Targets Virion Envelope Lipids To Inhibit Fusion of Influenza Virus, Hepatitis C Virus, and Other Enveloped Viruses

“…aUY11 was added to 2.5 ml of aqueous fusion buffer or to 2.5 ml of 1-octanol to a final concentration of 48 nM or 0.48 nM, respectively, in a polymethacrylate cuvette prewarmed to 37°C. Alternatively, aUY11 was added to 10 7 PFU of VSV, 10 7 PFU of HSV-1, 10 6 PFU of influenza virus, 10 6 FFU of HCV, or 2 nmol protein-free POPC liposomes in the same aqueous buffer to a final concentration of 48 nM. We also analyzed the fluorescence spectra of dUY11 in the same environments.…”

“…Enrichment of lipids with polar headgroups of larger diameter than their hydrophobic tails in the outer leaflet favors positive curvature, increasing the activation energy required to form the hemifusion stalk and thereby inhibiting viral fusion (6,36). Accordingly, addition of exogenous lipids of the appropriate shape and polarity (such as LPC) prevents the fusion of many enveloped viruses (8)(9)(10)(37)(38)(39). Phospholipids, however, are not likely to be pharmacologically useful.…”

“…Conversely, enrichment in the outer leaflet of lipids that favor positive curvature, specifically those with hydrophilic headgroups larger than their hydrophobic tails (such as lysophosphatidylcholine [LPC]), impairs fusion (6). Such phospholipids prevent the fusion of enveloped viruses, such as influenza virus (7,8), rabies virus (9), and Sendai virus (10). However, such phospholipids also tend to be disruptive to all membranes (including cellular ones), to have signaling activities, to be toxic, and to be too rapidly metabolized to be useful as drugs.…”

Hydrophobic Aminostyryl Quinolinium Dyes as New Fluorescent Stains for Proteins in Sodium Dodecyl Sulfate‐polyacrylamide Gel

“…For example, octadecyl rhodamine B dye was used to monitor membrane fusion process. 6,7 Fluorescein derivatives with a tail were commonly utilized for fluorescence recovery after photobleaching (FRAP) measurement of lipid lateral diffusion. 8 Lipophilic coumarin derivatives were also prepared and used as a pH sensor.…”

Content mixing and membrane integrity during membrane fusion driven by pairing of isolated v-SNAREs and t-SNAREs

“…Content mixing assays typically rely on the detection of fluorescence to monitor the intermixing of soluble compounds trapped in previously separate liposome populations (26)(27)(28)(29)(30). Unfortunately, these assay systems turned out to be less suitable to monitor SNARE-dependent membrane fusion because one of them [ANTS͞DPX system (30)] has been reported not to provide reliable data when small unilamellar liposomes are involved (30), such as those reconstituting SNARE proteins (17), whereas another assay [terbium͞dipicolinic acid (30)] is not All samples contained v-liposomes loaded with 33 P-labeled oligonucleotide 1 and were incubated for 120 min at 37°C.…”