scholarly journals Mutations in the PPPY Motif of Vesicular Stomatitis Virus Matrix Protein Reduce Virus Budding by Inhibiting a Late Step in Virion Release

2000 ◽  
Vol 74 (21) ◽  
pp. 9818-9827 ◽  
Author(s):  
Himangi R. Jayakar ◽  
K. Gopal Murti ◽  
Michael A. Whitt

ABSTRACT The N terminus of the matrix (M) protein of vesicular stomatitis virus (VSV) and of other rhabdoviruses contains a highly conserved PPPY sequence (or PY motif) similar to the late (L) domains in the Gag proteins of some retroviruses. These L domains in retroviral Gag proteins are required for efficient release of virus particles. In this report, we show that mutations in the PPPY sequence of the VSV M protein reduce virus yield by blocking a late stage in virus budding. We also observed a delay in the ability of mutant viruses to cause inhibition of host gene expression compared to wild-type (WT) VSV. The effect of PY mutations on virus budding appears to be due to a block at a stage just prior to virion release, since electron microscopic examination of PPPA mutant-infected cells showed a large number of assembled virions at the plasma membrane trapped in the process of budding. Deletion of the glycoprotein (G) in addition to these mutations further reduced the virus yield to less than 1% of WT levels, and very few particles were assembled at the cell surface. This observation suggested that G protein aids in the initial stage of budding, presumably during the formation of the bud site. Overall, our results confirm that the PPPY sequence of the VSV M protein possesses L domain activity analogous to that of the retroviral Gag proteins.

2009 ◽  
Vol 83 (6) ◽  
pp. 2611-2622 ◽  
Author(s):  
Subash C. Das ◽  
Debasis Panda ◽  
Debasis Nayak ◽  
Asit K. Pattnaik

ABSTRACT A recombinant vesicular stomatitis virus (VSV-PeGFP-M-MmRFP) encoding enhanced green fluorescent protein fused in frame with P (PeGFP) in place of P and a fusion matrix protein (monomeric red fluorescent protein fused in frame at the carboxy terminus of M [MmRFP]) at the G-L gene junction, in addition to wild-type (wt) M protein in its normal location, was recovered, but the MmRFP was not incorporated into the virions. Subsequently, we generated recombinant viruses (VSV-PeGFP-ΔM-Mtc and VSV-ΔM-Mtc) encoding M protein with a carboxy-terminal tetracysteine tag (Mtc) in place of the M protein. These recombinant viruses incorporated Mtc at levels similar to M in wt VSV, demonstrating recovery of infectious rhabdoviruses encoding and incorporating a tagged M protein. Virions released from cells infected with VSV-PeGFP-ΔM-Mtc and labeled with the biarsenical red dye (ReAsH) were dually fluorescent, fluorescing green due to incorporation of PeGFP in the nucleocapsids and red due to incorporation of ReAsH-labeled Mtc in the viral envelope. Transport and subsequent association of M protein with the plasma membrane were shown to be independent of microtubules. Sequential labeling of VSV-ΔM-Mtc-infected cells with the biarsenical dyes ReAsH and FlAsH (green) revealed that newly synthesized M protein reaches the plasma membrane in less than 30 min and continues to accumulate there for up to 2 1/2 hours. Using dually fluorescent VSV, we determined that following adsorption at the plasma membrane, the time taken by one-half of the virus particles to enter cells and to uncoat their nucleocapsids in the cytoplasm is approximately 28 min.


2009 ◽  
Vol 83 (23) ◽  
pp. 12139-12150 ◽  
Author(s):  
Chad E. Mire ◽  
Derek Dube ◽  
Sue E. Delos ◽  
Judith M. White ◽  
Michael A. Whitt

ABSTRACT To study vesicular stomatitis virus (VSV) entry and uncoating, we generated a recombinant VSV encoding a matrix (M) protein containing a C-terminal tetracysteine Lumio tag (rVSV-ML) that could be fluorescently labeled using biarsenical compounds. Quantitative confocal microscopy showed that there is a transient loss of fluorescence at early times after the initiation of endocytosis of rVSV-ML-Green (rVSV-MLG) virions, which did not occur when cells were treated with bafilomycin A1. The reduction in fluorescence occurred 5 to 10 min postentry, followed by a steady increase in fluorescence intensity from 15 to 60 min postentry. A similar loss of fluorescence was observed in vitro when virions were exposed to acidic pH. The reduction in fluorescence required G protein since “bald” ΔG-MLG particles did not show a similar loss of fluorescence at low pH. Based on the pH-dependent fluorescence properties of Lumio Green, we hypothesize that the loss of fluorescence of rVSV-MLG virions during virus entry is due to a G ectodomain-dependent acidification of the virion interior. Biochemical analysis indicated that low pH also resulted in an enhancement of M protein dissociation from partially permeabilized, but otherwise intact, wild-type virions. From these data we propose that low-pH conformational changes in G protein promote acidification of the virus interior, which facilitates the release of M from ribonucleoprotein particles during uncoating.


2006 ◽  
Vol 87 (11) ◽  
pp. 3379-3384 ◽  
Author(s):  
Brian D. Lichty ◽  
Heidi McBride ◽  
Stephen Hanson ◽  
John C. Bell

Vesicular stomatitis virus (VSV) is a rhabdovirus that has attracted attention of late as an oncolytic virus and as a vaccine vector. Mutations in the matrix (M) gene of VSV yield attenuated strains that may be very useful in both settings. As a result of this interest in the M protein, this study analysed various M–green fluorescent protein (GFP) fusion constructs. Remarkably, fusion of the N terminus of the M protein to GFP targeted the fluorescent protein to the surface of mitochondria. Mutational analysis indicated that a mitochondrial-targeting motif exists within aa 33–67. Expression of these fusion proteins led to loss of mitochondrial membrane permeability and to an alteration in mitochondrial organization mirroring that seen during viral infection. In addition, a portion of the M protein present in infected cells co-purified with mitochondria. This work may indicate a novel function for this multifunctional viral protein.


1984 ◽  
Vol 62 (11) ◽  
pp. 1174-1180 ◽  
Author(s):  
John Capone ◽  
Hara P. Ghosh

The matrix protein M and the nucleocapsid protein N were isolated from vesicular stomatitis virus and reconstituted into artificial phospholipid vesicles. While the M protein could be reconstituted into phospholipid vesicles, the N protein had no affinity for lipid vesicles. The N protein could, however, associate with phospholipid vesicles in the presence of M protein. Identical results were also obtained when an in vitro system synthesizing M and N proteins was used for reconstitution. The results suggest that M protein is involved in virus maturation by interacting with the viral envelope and the N protein of the nucleoprotein core.


2010 ◽  
Vol 84 (24) ◽  
pp. 12609-12618 ◽  
Author(s):  
Hélène Raux ◽  
Linda Obiang ◽  
Nicolas Richard ◽  
Francis Harper ◽  
Danielle Blondel ◽  
...  

ABSTRACT Matrix proteins (M) direct the process of assembly and budding of viruses belonging to the Mononegavirales order. Using the two-hybrid system, the amino-terminal part of vesicular stomatitis virus (VSV) M was shown to interact with dynamin pleckstrin homology domain. This interaction was confirmed by coimmunoprecipitation of both proteins in cells transfected by a plasmid encoding a c-myc-tagged dynamin and infected by VSV. A role for dynamin in the viral cycle (in addition to its role in virion endocytosis) was suggested by the fact that a late stage of the viral cycle was sensitive to dynasore. By alanine scanning, we identified a single mutation of M protein that abolished this interaction and reduced virus yield. The adaptation of mutant virus (M.L4A) occurred rapidly, allowing the isolation of revertants, among which the M protein, despite having an amino acid sequence distinct from that of the wild type, recovered a significant level of interaction with dynamin. This proved that the mutant phenotype was due to the loss of interaction between M and dynamin. The infectious cycle of the mutant virus M.L4A was blocked at a late stage, resulting in a quasi-absence of bullet-shaped viruses in the process of budding at the cell membrane. This was associated with an accumulation of nucleocapsids at the periphery of the cell and a different pattern of VSV glycoprotein localization. Finally, we showed that M-dynamin interaction affects clathrin-dependent endocytosis. Our study suggests that hijacking the endocytic pathway might be an important feature for enveloped virus assembly and budding at the plasma membrane.


1998 ◽  
Vol 72 (10) ◽  
pp. 8413-8419 ◽  
Author(s):  
Maryam Ahmed ◽  
Douglas S. Lyles

ABSTRACT The matrix (M) protein of vesicular stomatitis virus (VSV) functions in virus assembly and inhibits host-directed gene expression independently of other viral components. Experiments in this study were carried out to determine the ability of M protein to inhibit transcription directed by each of the three host RNA polymerases (RNA polymerase I [RNAPI], RNAPII, and RNAPIII). The effects of wild-type (wt) VSV, v6 (a VSV mutant isolated from persistently infected cells), and tsO82 viruses on poly(A)+ and poly(A)− RNA synthesis were measured by incorporation of [3H]uridine. v6 andtsO82 viruses, which contain M-gene mutations, had a decreased ability to inhibit synthesis of both poly(A)+ and poly(A)− RNA. Nuclear runoff analysis showed that VSV inhibited transcription of 18S rRNA and α-tubulin genes, which was dependent on RNAPI and RNAPII, respectively, but infection with wt virus enhanced transcription of 5S rRNA by RNAPIII. The effect of M protein alone on transcription by RNAPI-, RNAPII-, and RNAPIII-dependent promoters was measured by cotransfection assays. M protein inhibited transcription from RNAPI- and RNAPII-dependent promoters in the absence of other viral gene products. RNAPIII-dependent transcription of the adenovirus VA promoters was also inhibited by M protein. However, as observed during wt VSV infection, M protein enhanced endogenous 5S rRNA transcription, indicating that the inhibition of transcription by RNAPIII was dependent on the nature of the promoter.


2020 ◽  
Author(s):  
Wei Pan ◽  
Hongmei Wang ◽  
Hongbin He

Abstract Background: Vesicular stomatitis virus (VSV) is an archetypal member of Mononegavirales which causes important diseases in cattle, horses and pigs. The matrix protein (M) of VSV plays critical roles in the replication, assembly/budding and pathogenesis of VSV. To further investigate the role of M during viral growth, we used a two-hybrid system to screen for host factors that interact with the M protein. Results: Here, NADH: ubiquinone oxidoreductase complex assembly factor 4 (Ndufaf4) was identified as an M-binding partner, and this interaction was confirmed by yeast cotransformation and GST pulldown assays. The globular domain of M was mapped and shown to be critical for the M-Ndufaf4 interaction. Two double mutations (E156A/H157A, D180A/E181A) in M impaired the M-Ndufaf4 interaction. Overexpression of Ndufaf4 inhibited VSV propagation, and knockdown of Ndufaf4 by short hairpin RNA (shRNA) markedly promoted VSV replication. Finally, we also demonstrate that the anti-VSV effect of Ndufaf4 is independent of activation of the type I IFN response. These results indicated that Ndufaf4 might exploit other mechanisms to affect VSV replication. Conclusions: In summary, we identify Ndufaf4 as a potential target for the inhibition of VSV propagation. These results provided further insight into the study of VSVpathogenesis.


2005 ◽  
Vol 86 (12) ◽  
pp. 3357-3363 ◽  
Author(s):  
Jérôme Solon ◽  
Olivier Gareil ◽  
Patricia Bassereau ◽  
Yves Gaudin

The matrix (M) protein of vesicular stomatitis virus plays a key role in both assembly and budding of progeny virions. In vitro experiments have shown a strong propensity of M protein to bind to vesicles containing negatively charged phospholipids. In vivo, it has also been demonstrated that recruitment of some cellular proteins by M protein is required for efficient virus budding and release of newly synthesized virions in the extracellular medium. The ability of M protein to deform target membranes in vitro was investigated in this study. It was shown that incubation of purified M protein with giant unilamellar vesicles results in the formation of patches of M protein at their surface, followed by deformations of the membrane toward the inside of the vesicle, which could be observed in phase-contrast microscopy. This provides the first evidence that M protein alone is able to impose the correct budding curvature on the membrane. Using confocal microscopy, patches of M protein that colocalized with negatively charged lipid domains a few minutes after vesicle injection were observed. After a longer incubation period, membrane deformations appeared in these domains. At this time, a strict colocalization of M protein, negatively charged lipids and membrane deformation was observed. The influence on this process of the basic N-terminal part of the protein and of the previously identified hydrophobic loop has also been investigated. Interestingly, the final fission event has never been observed in our experimental system, indicating that other partners are required for this step.


2007 ◽  
Vol 88 (9) ◽  
pp. 2559-2567 ◽  
Author(s):  
Takashi Irie ◽  
Elena Carnero ◽  
Atsushi Okumura ◽  
Adolfo García-Sastre ◽  
Ronald N. Harty

The matrix (M) protein of vesicular stomatitis virus (VSV) is a multi-functional protein involved in virus assembly, budding and pathogenesis. The 24PPPY27 late (L) domain of the M protein plays a key role in virus budding, whereas amino acids downstream of the PPPY motif contribute to host protein shut-off and pathogenesis. Using a panel of 37PSAP40 recombinant viruses, it has been demonstrated previously that the PSAP region of M does not possess L-domain activity similar to that of PPPY in BHK-21 cells. This study reports the unanticipated finding that these PSAP recombinants were attenuated in cell culture and in mice compared with control viruses. Indeed, PSAP recombinant viruses exhibited a small-plaque phenotype, reduced CPE, reduced levels of activated caspase-3, enhanced production of IFN-β and reduced titres in the lungs and brains of infected mice. In particular, recombinant virus M6PY>A4-R34E was the most severely attenuated, exhibiting little or no CPE in cell culture and undetectable titres in the lungs and brains of infected mice. These findings indicate an important role for the PSAP region (aa 33–44) of the M protein in the pathology of VSV infection and may have implications for the development of VSV as a vaccine and/or oncolytic vector.


2003 ◽  
Vol 77 (9) ◽  
pp. 5524-5528 ◽  
Author(s):  
Sarah A. Kopecky ◽  
Douglas S. Lyles

ABSTRACT The matrix (M) protein of vesicular stomatitis virus (VSV) expressed in the absence of other viral components causes many of the cytopathic effects of VSV, including an inhibition of host gene expression and the induction of cell rounding. It was recently shown that M protein also induces apoptosis in the absence of other viral components. This raises the possibility that the activation of apoptotic pathways causes the inhibition of host gene expression and cell rounding by M protein. To test this hypothesis, host gene expression and cell rounding were analyzed after the transfection of M mRNA into HeLa cells stably overexpressing Bcl-2 (HeLa-Bcl-2 cells). We have shown previously that Bcl-2 inhibits M-protein-induced apoptosis. Here, we show that activation of the apoptotic pathways downstream of Bcl-2 is not required for the inhibition of host gene expression by M protein. In contrast, overexpression of Bcl-2 inhibited cell rounding induced by M protein, indicating that apoptotic pathways downstream of Bcl-2 are required for the cell-rounding activities of M protein.


Sign in / Sign up

Export Citation Format

Share Document