scholarly journals Organization of the Vesicular Stomatitis Virus Glycoprotein into Membrane Microdomains Occurs Independently of Intracellular Viral Components

2003 ◽  
Vol 77 (7) ◽  
pp. 3985-3992 ◽  
Author(s):  
Erica L. Brown ◽  
Douglas S. Lyles

ABSTRACT The glycoprotein (G protein) of vesicular stomatitis virus (VSV) is primarily organized in plasma membranes of infected cells into membrane microdomains with diameters of 100 to 150 nm, with smaller amounts organized into microdomains of larger sizes. This organization has been observed in areas of the infected-cell plasma membrane that are outside of virus budding sites as well as in the envelopes of budding virions. These observations raise the question of whether the intracellular virion components play a role in organizing the G protein into membrane microdomains. Immunogold-labeling electron microscopy was used to analyze the distribution of the G protein in arbitrarily chosen areas of plasma membranes of transfected cells that expressed the G protein in the absence of other viral components. Similar to the results with virus-infected cells, the G protein was organized predominantly into membrane microdomains with diameters of approximately 100 to 150 nm. These results indicate that internal virion components are not required to concentrate the G protein into membrane microdomains with a density similar to that of virus envelopes. To determine if interactions between the G protein cytoplasmic domain and internal virion components were required to create a virus budding site, cells infected with recombinant VSVs encoding truncation mutations of the G protein cytoplasmic domain were analyzed by immunogold-labeling electron microscopy. Deletion of the cytoplasmic domain of the G protein did not alter its partitioning into the 100- to 150-nm microdomains, nor did it affect the incorporation of the G protein into virus envelopes. These data support a model for virus assembly in which the G protein has the inherent property of partitioning into membrane microdomains that then serve as the sites of assembly of internal virion components.

2005 ◽  
Vol 79 (11) ◽  
pp. 7077-7086 ◽  
Author(s):  
Erica L. Brown ◽  
Douglas S. Lyles

ABSTRACT Many plasma membrane components are organized into detergent-resistant membrane microdomains referred to as lipid rafts. However, there is much less information about the organization of membrane components into microdomains outside of lipid rafts. Furthermore, there are few approaches to determine whether different membrane components are colocalized in microdomains as small as lipid rafts. We have previously described a new method of determining the extent of organization of proteins into membrane microdomains by analyzing the distribution of pairwise distances between immunogold particles in immunoelectron micrographs. We used this method to analyze the microdomains involved in the incorporation of the T-cell antigen CD4 into the envelope of vesicular stomatitis virus (VSV). In cells infected with a recombinant virus that expresses CD4 from the viral genome, both CD4 and the VSV envelope glycoprotein (G protein) were found in detergent-soluble (nonraft) membrane fractions. However, analysis of the distribution of CD4 and G protein in plasma membranes by immunoelectron microscopy showed that both were organized into membrane microdomains of similar sizes, approximately 100 to 150 nm. In regions of plasma membrane outside of virus budding sites, CD4 and G protein were present in separate membrane microdomains, as shown by double-label immunoelectron microscopy data. However, virus budding occurred from membrane microdomains that contained both G protein and CD4, and extended to approximately 300 nm, indicating that VSV pseudotype formation with CD4 occurs by clustering of G protein- and CD4-containing microdomains.


2008 ◽  
Vol 82 (11) ◽  
pp. 5536-5547 ◽  
Author(s):  
B. Dancho Swinteck ◽  
Douglas S. Lyles

ABSTRACT Immunogold electron microscopy and analysis were used to determine the organization of the major structural proteins of vesicular stomatitis virus (VSV) during virus assembly. We determined that matrix protein (M protein) partitions into plasma membrane microdomains in VSV-infected cells as well as in transfected cells expressing M protein. The sizes of the M-protein-containing microdomains outside the virus budding sites (50 to 100 nm) were smaller than those at sites of virus budding (approximately 560 nm). Glycoprotein (G protein) and M protein microdomains were not colocalized in the plasma membrane outside the virus budding sites, nor was M protein colocalized with microdomains containing the host protein CD4, which efficiently forms pseudotypes with VSV envelopes. These results suggest that separate membrane microdomains containing either viral or host proteins cluster or merge to form virus budding sites. We also determined whether G protein or M protein was colocalized with VSV nucleocapsid protein (N protein) outside the budding sites. Viral nucleocapsids were observed to cluster in regions of the cytoplasm close to the plasma membrane. Membrane-associated N protein was colocalized with G protein in regions of plasma membrane of approximately 600 nm. In contrast to the case for G protein, M protein was not colocalized with these areas of nucleocapsid accumulation. These results suggest a new model of virus assembly in which an interaction of VSV nucleocapsids with G-protein-containing microdomains is a precursor to the formation of viral budding sites.


1988 ◽  
Vol 8 (7) ◽  
pp. 2869-2874
Author(s):  
J L Guan ◽  
A Ruusala ◽  
H Cao ◽  
J K Rose

Alterations of the cytoplasmic domain of the vesicular stomatitis virus glycoprotein (G protein) were shown previously to affect transport of the protein from the endoplasmic reticulum, and recent studies have shown that this occurs without detectable effects on G protein folding and trimerization (R. W. Doms et al., J. Cell Biol., in press). Deletions within this domain slowed exit of the mutant proteins from the endoplasmic reticulum, and replacement of this domain with a foreign 12-amino-acid sequence blocked all transport out of the endoplasmic reticulum. To extend these studies, we determined whether such effects of cytoplasmic domain changes were transferable to other proteins. Three different assays showed that the effects of the mutations on transport of two membrane-anchored secretory proteins were the same as those observed with vesicular stomatitis virus G protein. In addition, possible effects on oligomerization were examined for both transported and nontransported forms of membrane-anchored human chorionic gonadotropin-alpha. These membrane-anchored forms, like the nonanchored human chorionic gonadotropin-alpha, had sedimentation coefficients consistent with a monomeric structure. Taken together, our results provide strong evidence that these cytoplasmic mutations affect transport by affecting interactions at or near the cytoplasmic side of the membrane.


1986 ◽  
Vol 102 (6) ◽  
pp. 2147-2157 ◽  
Author(s):  
L Puddington ◽  
C E Machamer ◽  
J K Rose

Oligonucleotide-directed mutagenesis was used to construct chimeric cDNAs that encode the extracellular and transmembrane domains of the vesicular stomatitis virus glycoprotein (G) linked to the cytoplasmic domain of either the immunoglobulin mu membrane heavy chain, the hemagglutinin glycoprotein of influenza virus, or the small glycoprotein (p23) of infectious bronchitis virus. Biochemical analyses and immunofluorescence microscopy demonstrated that these hybrid genes were correctly expressed in eukaryotic cells and that the hybrid proteins were transported to the plasma membrane. The rate of transport to the Golgi complex of G protein with an immunoglobulin mu membrane cytoplasmic domain was approximately sixfold slower than G protein with its normal cytoplasmic domain. However, this rate was virtually identical to the rate of transport of micron heavy chain molecules measured in the B cell line WEHI 231. The rate of transport of G protein with a hemagglutinin cytoplasmic domain was threefold slower than wild type G protein and G protein with a p23 cytoplasmic domain, which were transported at similar rates. The combined results underscore the importance of the amino acid sequence in the cytoplasmic domain for efficient transport of G protein to the cell surface. Also, normal cytoplasmic domains from other transmembrane glycoproteins can substitute for the G protein cytoplasmic domain in transport of G protein to the plasma membrane. The method of constructing precise hybrid proteins described here will be useful in defining functions of specific domains of viral and cellular integral membrane proteins.


1988 ◽  
Vol 8 (7) ◽  
pp. 2869-2874 ◽  
Author(s):  
J L Guan ◽  
A Ruusala ◽  
H Cao ◽  
J K Rose

Alterations of the cytoplasmic domain of the vesicular stomatitis virus glycoprotein (G protein) were shown previously to affect transport of the protein from the endoplasmic reticulum, and recent studies have shown that this occurs without detectable effects on G protein folding and trimerization (R. W. Doms et al., J. Cell Biol., in press). Deletions within this domain slowed exit of the mutant proteins from the endoplasmic reticulum, and replacement of this domain with a foreign 12-amino-acid sequence blocked all transport out of the endoplasmic reticulum. To extend these studies, we determined whether such effects of cytoplasmic domain changes were transferable to other proteins. Three different assays showed that the effects of the mutations on transport of two membrane-anchored secretory proteins were the same as those observed with vesicular stomatitis virus G protein. In addition, possible effects on oligomerization were examined for both transported and nontransported forms of membrane-anchored human chorionic gonadotropin-alpha. These membrane-anchored forms, like the nonanchored human chorionic gonadotropin-alpha, had sedimentation coefficients consistent with a monomeric structure. Taken together, our results provide strong evidence that these cytoplasmic mutations affect transport by affecting interactions at or near the cytoplasmic side of the membrane.


1994 ◽  
Vol 5 (2) ◽  
pp. 99-104 ◽  
Author(s):  
M. J. Almela ◽  
A. Irurzun ◽  
L. Carrasco

The naturally occurring isoflavonoid orobol exhibits antiviral effects against some animal viruses. Addition of the compound after virus entry inhibits the appearance of late viral protein synthesis in Vesicular Stomatitis Virus, influenza, or vaccinia virus-infected cells, but has no effect on poliovirus protein synthesis. Concentrations of the compound above 10–50 Mg ml−1 are sufficient to decrease the synthesis of VSV proteins when added early during infection, but have no effect on viral translation if added later, indicating that orobol does not block VSV translation directly. The synthesis of VSV nucleic acids is one of the targets of this flavonoid. The synthesis of both minus and plus-stranded viral RNA are inhibited by orobol when added during the first 2 h of infection. In addition, this compound interferes potently with the glycosylation of VSV G protein, indicating that orobol has several targets of antiviral action. The possibility that orobol interferes with the function of the cellular vesicular system is discussed.


2000 ◽  
Vol 74 (5) ◽  
pp. 2239-2246 ◽  
Author(s):  
Clinton S. Robison ◽  
Michael A. Whitt

ABSTRACT In this report, we show that the glycoprotein of vesicular stomatitis virus (VSV G) contains within its extracellular membrane-proximal stem (GS) a domain that is required for efficient VSV budding. To determine a minimal sequence in GS that provides for high-level virus assembly, we have generated a series of recombinant ΔG-VSVs which express chimeric glycoproteins having truncated stem sequences. The recombinant viruses having chimeras with 12 or more membrane-proximal residues of the G stem, and including the G protein transmembrane-cytoplasmic tail domains, produced near-wild-type levels of particles. In contrast, viruses encoding chimeras with shorter or no G-stem sequences produced ∼10- to 20-fold less. This budding domain when present in chimeric glycoproteins also promoted their incorporation into the VSV envelope. We suggest that the G-stem budding domain promotes virus release by inducing membrane curvature at sites where virus budding occurs or by recruiting condensed nucleocapsids to sites on the plasma membrane which are competent for efficient virus budding.


1988 ◽  
Vol 256 (3) ◽  
pp. 1021-1027 ◽  
Author(s):  
D Mack ◽  
J Kruppa

The cysteine residue in the cytoplasmic domain at position 489 of the sequence of the glycoprotein (G protein) isolated from vesicular-stomatitis virions is completely blocked for carboxymethylation. After release of covalently bound fatty acids by hydroxylamine at pH 6.8, this cysteine residue could be specifically labelled by iodo[14C]acetic acid. Reaction products were analysed after specific cleavage of labelled G protein at asparagine-glycine bonds by hydroxylamine at pH 9.3, which generated a C-terminal peptide of Mr 15,300 containing only the single cysteine residue. Bromelain digestion of [3H]palmitic acid-labelled membrane fractions of vesicular-stomatitis-virus-infected baby-hamster kidney cells removed almost completely the 3H radioactivity from the cytoplasmic domain of the G protein, whereas the ectodomain was completely protected by the microsomal membrane. This result indicates that the acylation site of the G protein is exposed on the cytoplasmic side of intracellular membranes. Taken together, both biochemical techniques strongly suggest that the single cysteine-489 residue, which is located six amino acid residues distal to the putative transmembrane domain, is the acylation site. The thioester bond between palmitic acid and the G protein is quite resistant to hydroxylamine treatment (0.32 M at pH 6.8 for 1 h at 37 degrees C) compared with the reactivity of the thioester linkage in palmitoyl-CoA, which is cleaved at relatively low concentrations of hydroxylamine (0.05 M).


1989 ◽  
Vol 109 (5) ◽  
pp. 2057-2065 ◽  
Author(s):  
D Mack ◽  
B Kluxen ◽  
J Kruppa

G1 and G2 are two forms of the membrane-integrated G protein of vesicular stomatitis virus that migrate differently in gel electrophoresis because G1 is modified by high-mannose and G2 by complex-type oligosaccharide side chains. The cytoplasmic domain in G1 is less exposed to cleavage by several proteases than in G2 molecules. Acylation by palmitic acid as well as inhibition of carbohydrate processing by swainsonine and deoxynojirimycin resulted in the same pattern of proteolytic sensitivity of both glycoproteins as in untreated cells. In contrast, accessibility of the cytoplasmic domain to proteases did not change when the intracellular transport of the G protein was blocked in carbonyl cyanide m-chlorophenylhydrazone- or monensin-treated BHK-21 cells, respectively. The results suggest that the increase in accessibility of the cytoplasmic tail of the G protein occurs after the monensin block in the trans-Golgi and might reflect a conformational change of functional significance--i.e., making the cytoplasmic domain of the viral spike protein competent for its interaction with the viral core, inducing thereby the formation of the budding virus particle.


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