Navegando por Palavras-chave "membrane fusion"

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    Charged residues are involved in membrane fusion mediated by a hydrophilic peptide located in vesicular stomatitis virus G protein
    (Taylor & Francis Ltd, 2006-09-01) Carneiro, Fabiana A.; Vandenbussche, Guy; Juliano, Maria A.; Juliano, Luiz; Ruysschaert, Jean-Marie; Da Poian, Andrea T.; Universidade Federal do Rio de Janeiro (UFRJ); Univ Libre Bruxelles; Universidade Federal de São Paulo (UNIFESP)
    Membrane fusion is an essential step of the internalization process of the enveloped animal viruses. Vesicular stomatitis virus (VSV) infection is mediated by virus spike glycoprotein G, which induces membrane fusion at the acidic environment of the endosomal compartment. in a previous work, we identified a specific sequence in VSV G protein, comprising the residues 145 to 164, directly involved in membrane interaction and fusion. Unlike fusion peptides from other viruses, this sequence is very hydrophilic, containing six charged residues, but it was as efficient as the virus in catalyzing membrane fusion at pH 6.0. Using a carboxyl-modifying agent, dicyclohexylcarbodiimide (DCCD), and several synthetic mutant peptides, we demonstrated that the negative charges of peptide acidic residues, especially Asp(153) and Glu(158), participate in the formation of a hydrophobic domain at pH 6.0, which is necessary to the peptide-induced membrane fusion. the formation of the hydrophobic region and the membrane fusion itself were dependent on peptide concentration in a higher than linear fashion, suggesting the involvement of peptide oligomerization. His(148) was also necessary to hydrophobicity and fusion, suggesting that peptide oligomerization occurs through intermolecular electrostatic interactions between the positively-charged His and a negatively-charged acidic residue of two peptide molecules. Oligomerization of hydrophilic peptides creates a hydrophobic region that is essential for the interaction with the membrane that results in fusion.
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    Interaction between dengue virus fusion peptide and lipid bilayers depends on peptide clustering
    (Taylor & Francis Ltd, 2008-01-01) Stauffer, Fausto; Melo, Manuel Nuno; Carneiro, Fabiana A.; Sousa, Francisco J. R.; Juliano, Maria A. [UNIFESP]; Juliano, Luiz [UNIFESP]; Mohana-Borges, Ronaldo; Da Poian, Andrea T.; Castanho, Miguel A. R. B.; UL; Universidade Federal do Rio de Janeiro (UFRJ); Universidade Federal de São Paulo (UNIFESP)
    Dengue fever is one of the most widespread tropical diseases in the world. the disease is caused by a virus member of the Flaviviridae family, a group of enveloped positive sense single-stranded RNA viruses. Dengue virus infection is mediated by virus glycoprotein E, which binds to the cell surface. After uptake by endocytosis, this protein induces the fusion between viral envelope and endosomal membrane at the acidic environment of the endosomal compartment. in this work, we evaluated by steady-state and time-resolved fluorescence spectroscopy the interaction between the peptide believed to be the dengue virus fusion peptide and large unilamellar vesicles, studying the extent of partition, fusion capacity and depth of insertion in membranes. the roles of the bilayer composition (neutral and anionic phospholipids), ionic strength and pH of the medium were also studied. Our results indicate that dengue virus fusion peptide has a high affinity to vesicles composed of anionic lipids and that the interaction is mainly electrostatic. Both partition coefficient and fusion index are enhanced by negatively charged phospholipids. the location determined by differential fluorescence quenching using lipophilic probes demonstrated that the peptide is in an intermediate depth in the hemilayers, in-between the bilayer core and its surface. Ultimately, these data provide novel insights on the interaction between dengue virus fusion peptide and its target membranes, namely, the role of oligomerization and specific types of membranes.
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    A minor beta-structured conformation is the active state of a fusion peptide of vesicular stomatitis virus glycoprotein
    (Wiley-Blackwell, 2008-04-01) Sarzedas, Carolina G.; Lima, Carla S.; Juliano, Maria A. [UNIFESP]; Juliano, Luiz [UNIFESP]; Valente, Ana Paula; Da Poian, Andrea T.; Almeida, Fabio C. L.; Universidade Federal do Rio de Janeiro (UFRJ); Universidade Federal de São Paulo (UNIFESP)
    Entry of enveloped animal viruses into their host cells always depends on a step of membrane fusion triggered by conformational changes in viral envelope glycoproteins. Vesicular stomatitis virus (VSV) infection is mediated by virus spike glycoprotein G, which induces membrane fusion at the acidic environment of the endosomal compartment. in a previous work, we identified a specific sequence in the VSV G protein, comprising the residues 145-164, directly involved in membrane interaction and fusion. in the present work we studied the interaction of pep[145-164] with membranes using NMR to solve the structure of the peptide in two membrane-mimetic systems: SDS micelles and liposomes composed of phosphatidylcholme and phosphatidylserine (PC: PS vesicles). the presence of medium-range NOEs showed that the peptide has a tendency to form N- and C-terminal helical segments in the presence of SDS micelles. Analysis of the chemical shift index indicated helix-coil equilibrium for the C-terminal helix under all conditions studied. At pH 7.0, the N-terminal helix also displayed a helix-coil equilibrium when pep[145-164] was free in solution or in the presence of PC: PS. Remarkably, at the fusogenic pH, the region of the N-terminal helix in the presence of SDS or PC: PS presented a third conformational species that was in equilibrium with the helix and random coil. the N-terminal helix content decreases pH and the minor P-structured conformation becomes more prevalent at the fusogenic pH. These data point to a P-conformation as the fusogenic active structure-which is in agreement with the X-ray structure, which shows a P-hairpin for the region corresponding to pep[145-164]. Copyright (c) 2007 European Peptide Society and John Wiley & Sons, Ltd.
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    Probing the interaction between vesicular stomatitis virus and phosphatidylserine
    (Springer, 2006-01-01) Carneiro, F. A.; Lapido-Loureiro, P. A.; Cordo, S. M.; Stauffer, F.; Weissmuller, G.; Bianconi, M. L.; Juliano, M. A.; Juliano, L.; Bisch, P. M.; Poian, ATD; Universidade Federal do Rio de Janeiro (UFRJ); Univ Buenos Aires; Universidade Federal de São Paulo (UNIFESP)
    The entry of enveloped animal viruses into their host cells always depends on membrane fusion triggered by conformational changes in viral envelope glycoproteins. Vesicular stomatitis virus (VSV) infection is mediated by virus spike glycoprotein G, which induces membrane fusion between the viral envelope and the endosomal membrane at the acidic environment of this compartment. in this work, we evaluated VSV interactions with membranes of different phospholipid compositions, at neutral and acidic pH, using atomic force microscopy (AFM) operating in the force spectroscopy mode, isothermal calorimetry (ITC) and molecular dynamics simulation. We found that the binding forces differed dramatically depending on the membrane phospholipid composition, revealing a high specificity of G protein binding to membranes containing phosphatidylserine ( PS). in a previous work, we showed that the sequence corresponding amino acid 145-164 of VSV G protein was as efficient as the virus in catalyzing membrane fusion at pH 6.0. Here, we used this sequence to explore VSV-PS interaction using ITC. We found that peptide binding to membranes was exothermic, suggesting the participation of electrostatic interactions. Peptide-membrane interaction at pH 7.5 was shown to be specific to PS and dependent on the presence of His residues in the fusion peptide. the application of the simplified continuum Gouy-Chapman theory to our system predicted a pH of 5.0 at membrane surface, suggesting that the His residues should be protonated when located close to the membrane. Molecular dynamics simulations suggested that the peptide interacts with the lipid bilayer through its N-terminal residues, especially Val(145) and His(148).