Search results for "Lipid bilayer fusion"
showing 10 items of 30 documents
Intracellular route of canine parvovirus entry.
1998
ABSTRACT The present study was designed to investigate the endocytic pathway involved in canine parvovirus (CPV) infection. Reduced temperature (18°C) or the microtubule-depolymerizing drug nocodazole was found to inhibit productive infection of canine A72 cells by CPV and caused CPV to be retained in cytoplasmic vesicles as indicated by immunofluorescence microscopy. Consistent with previously published results, these data indicate that CPV enters a host cell via an endocytic route and further suggest that microtubule-dependent delivery of CPV to late endosomes is required for productive infection. Cytoplasmic microinjection of CPV particles was used to circumvent the endocytosis and membr…
Fusion of biological membranes
2005
The process of membrane fusion has been examined by Monte Carlo simulation, and is found to be very different than the conventional picture. The differences in mechanism lead to several predictions, in particular that fusion is accompanied by transient leakage. This prediction has recently been verified. Self-consistent field theory is applied to examine the free energy barriers in the different scenarios.
Protein delivery by subviral particles of human cytomegalovirus
2003
Direct protein delivery is an emerging technology in vaccine development and gene therapy. We could previously show that subviral dense bodies (DB) of human cytomegalovirus (HCMV), a beta-herpesvirus, transport viral proteins into target cells by membrane fusion. Thus these non-infectious particles provide a candidate delivery system for the prophylactic and therapeutic application of proteins. Here we provide proof of principle that DB can be modified genetically. A 55 kDa fusion protein consisting of the green fluorescent protein and the neomycin phosphotransferase could be packed in and delivered into cells by recombinant DB in a functional fashion. Furthermore, transfer of protein into …
PspA adopts an ESCRT-III-like fold and remodels bacterial membranes
2020
SummaryPspA is the main effector of the phage shock protein (Psp) system and preserves the bacterial inner membrane integrity and function. Here, we present the 3.6 Å resolution cryo-EM structure of PspA assembled in helical rods. PspA monomers adopt a canonical ESCRT-III fold in an extended open conformation. PspA rods are capable of enclosing lipids and generate positive membrane curvature. Using cryo-EM we visualized how PspA remodels membrane vesicles into μm-sized structures and how it mediates the formation of internalized vesicular structures. Hot spots of these activities are zones derived from PspA assemblies, serving as lipid transfer platforms and linking previously separated lip…
Field theoretic study of bilayer membrane fusion: I. Hemifusion mechanism
2003
Self-consistent field theory is used to determine structural and energetic properties of metastable intermediates and unstable transition states involved in the standard stalk mechanism of bilayer membrane fusion. A microscopic model of flexible amphiphilic chains dissolved in hydrophilic solvent is employed to describe these self-assembled structures. We find that the barrier to formation of the initial stalk is much smaller than previously estimated by phenomenological theories. Therefore its creation it is not the rate limiting process. The barrier which is relevant is associated with the rather limited radial expansion of the stalk into a hemifusion diaphragm. It is strongly affected by…
Coarse-grained models and collective phenomena in membranes: Computer simulation of membrane fusion
2003
We discuss the role coarse-grained models play in in- vestigating collective phenomena in bilayer membranes and place them in the context of alternative approaches. By reducing the de- grees of freedom and applying simple effective potentials, coarse- grained models can address the large time scales and length scales of collective phenomena in mem- branes. Although the mapping from a coarse-grained model onto chemi- cally realistic models is a challenge, such models provide a direct view on the phenomena that occur on the length scales of a few tens of nano- meters. Their relevance is exempli- ied by the study of fusion of model membranes. ' 2003 Wiley Periodicals,
Vesicle transport and photoreceptor death: fishing for molecular links.
2013
Intracellular vesicle transport defects can induce retinal degeneration and photoreceptor cell death, but the molecular connections between these processes remains poorly understood. Reporting in Developmental Cell, Nishiwaki et al. (2013) suggest that a vesicle fusion cis-SNARE complex component translates vesicular transport defects into photoreceptor cell apoptosis.
Calcium-dependent conformational changes of membrane-bound Ebola fusion peptide drive vesicle fusion
2003
AbstractThe fusogenic subdomain of the Ebola virus envelope glycoprotein is an internal sequence located ca. 20 residues downstream the N-terminus of the glycoprotein transmembrane subunit. Partitioning of the Ebola fusion peptide into membranes containing phosphatidylinositol in the absence of Ca2+ stabilizes an α-helical conformation, and gives rise to vesicle efflux but not vesicle fusion. In the presence of millimolar Ca2+ the membrane-bound peptide adopts an extended β-structure, and induces inter-vesicle mixing of lipids. The peptide conformational polymorphism may be related to the flexibility of the virus–cell intermembrane fusogenic complex.
Occlusion-derived baculovirus: interaction with human cells and evaluation of the envelope protein P74 as a surface display platform.
2008
To develop complementary baculovirus-based tools for gene delivery and display technologies, the interaction of occlusion-derived baculovirus (ODV) with human cells, and the functionality of the P74 ODV envelope protein for display of the IgG-binding Z domains (ZZP74) were evaluated. The cellular binding of ODV was concentration-dependent and saturable. Only minority of the bound virions were internalized at both 37 and 4 degrees C, suggesting usage of direct membrane fusion as the entry mode. The intracellular transport of ODV was confined in vesicular structures peripheral to the plasma membrane, impeding subsequent nuclear entry and transgene expression. Transduction of ODV was not rescu…
Binding and internalization of human papillomavirus type 33 virus-like particles by eukaryotic cells
1995
Infection of cells by human papillomaviruses (HPVs) associated with malignant genital lesions has not been studied because of the lack of an in vitro system and the unavailability of virions. We have now used virus-like particles (VLPs) of HPV type 33 to analyze the initial events in the interaction of the HPV capsid with cell lines. Binding of VLPs to HeLa cells was observed in biochemical assays and by immunofluorescence. VLP binding was inhibited by antisera raised against VLPs but not by monoclonal antibodies recognizing either L1 or L2 epitopes accessible on VLPs. Under saturating conditions, approximately 2 x 10(4) VLPs were bound per cell, with a dissociation constant of about 100 pM…