The M Protein of Vesicular Stomatitis Virus (original) (raw)
Related papers
Journal of virology, 1977
Maturation of viral proteins in cells infected with mutants of vesicular stomatitis virus was studied by surface iodination and cell fractionation. The movement of G, M, and N proteins to the virion bud appeared to be interdependent. Mutations thought to be in G protein prevented its migration to the cell surface, allowed neither M nor N protein to become membrane bound, and blocked formation of viral particles. Mutant G protein appeared not to leave the endoplasmic reticulum at the nonpermissive temperature, but this defect was partially reversible. In cells infected with mutants that caused N protein to be degraded rapidly or prevented its assembly into nucleocapsids, M protein did not bind to membranes and G protein matured to the cell surface, but never entered structures with the density of virions. Mutations causing M protein to be degraded prevented virion formation, and G protein behaved as in cells infected by mutants in N protein. These results are consistent with a model ...
Separate pathways of maturation of the major structural proteins of vesicular stomatitis virus
Journal of virology, 1977
Cell fractionation and protein electrophoresis were used to study the intracellular sites of synthesis and intermediate structures in the assembly of the virion proteins of vesicular stomatitis virus. Each of the three major virion proteins assembled into virions through a separable pathway. The nucleocapsid (N) protein was first a soluble protein and later incorporated into free, cytoplasmic nucleocapsids. A small amount of N protein was bound to membranes at later times, presumably representing either nucleocapsids in the process of budding or completed virions attached to the cell surface. The matrix (M) protein also appeared to be synthesized as a soluble protein, but was then directly incorporated into membranous structures with the same density as whole virus. Very little M protein was ever found in membranes banding at the density of plasma membranes. The M protein entered extracellular virus very quickly, as though it moved directly from a soluble state into budding virus. I...
Archives of Biochemistry and Biophysics, 1997
Newcastle disease virus (NDV), 4 a member of the The irreversible thermal denaturation of Newcastle family of Paramixoviridae, is composed of an outer lipodisease virus was investigated using different tech-protein envelope and an internal helical nucleocapsid niques including high-sensitivity differential scanning (1). The nucleocapsid core contains a single-strand negcalorimetry, thermal gel analysis intrinsic fluoresative RNA, the NP nucleoprotein (55 kDa), the P phoscence, and neuraminidase activity assays. Application phoprotein (53 kDa), and the L polymerase protein (200 of a successive annealing procedure to the scanning kDa). The envelope is composed of a lipid bilayer, which calorimetric endotherm of Newcastle disease virus is acquired from the host plasma membrane, and has furnished four elementary thermal transitions below two transmembrane glycoproteins: the F protein (55 the overall endotherm; these were further identified kDa), which promotes virus-cell fusion, and the HN as coming from the denaturation of each viral protein. protein (74 kDa), having hemagglutinating and neur-The shape of these transitions, as well as their scanaminidase activities (2, 3). The possible presence of a rate dependence, was explained by assuming that specific site on the HN protein that interacts with the thermal denaturation takes place according to the ki-F protein in the fusion process has also been demonnetic scheme N r k D, where k is a first-order kinetic strated (4, 5). This type of virus can penetrate cells constant that changes with temperature, as given by through direct fusion with the plasma membrane at the Arrhenius equation; N is the native state; and D is neutral pH values (6, 7). There is another protein, imthe denatured state. On the basis of this model, activamediately below the viral envelope: the inner, nonglytion energy values were calculated. The data obtained cosylated M matrix protein (40 kDa), which interacts with the other methods used in this work support the electrostatically with the cytoplasmic part of the HN proposed two-state kinetic model. ᭧ 1997 Academic Press protein and with the contents of the nucleocapsid (8, 9), thus conferring rigidity to the virion structure. There is analysis; Newcastle disease virus.
Journal of Virology, 1985
Dark-field scanning transmission electron microscopy was used to perform mass analyses of purified vesicular stomatitis virions, pronase-treated virions, and nucleocapsids, leading to a complete self-consistent account of the molecular composition of vesicular stomatitis virus. The masses obtained were 265.6 +/- 13.3 megadaltons (MDa) for the native virion, 197.5 +/- 8.4 MDa for the pronase-treated virion, and 69.4 +/- 4.9 MDa for the nucleocapsid. The reduction in mass effected by pronase treatment, which corresponds to excision of the external domains (spikes) of G protein, leads to an average of 1,205 molecules of G protein per virion. The nucleocapsid mass, after compensation for the RNA (3.7 MDa) and residual amounts of other proteins, yielded a complement of 1,258 copies of N protein. Calibration of the amounts of M, NS, and L proteins relative to N protein by biochemical quantitation yielded values of 1,826, 466, and 50 molecules, respectively, per virion. Assuming that the r...
Journal of virology, 1977
The metabolism of viral RNA and proteins has been studied in cells infected with temperature-sensitive mutant strains of vesicular stomatitis virus. Certain viral proteins encoded by the mutant strains, usually the putative mutant protein for the assigned complementation group, were shown to be degraded more rapidly at the nonpermissive temperature than were the wild-type proteins. Group III mutants (tsG33, tsM301) encode M proteins which are degraded three- to fourfold faster than the wild-type protein. This defect cannot be fully rescued by coinfection with wild-type virus, and thus the defect appears to be in the M protein itself. Mutants tsM601 (VI) and tsG41(IV) encode N proteins which are degraded much faster than the wild-type protein and also share the property of being defective in replication of viral RNA, suggesting a correlation between these phenotypic properties. Furthermore, the L proteins of tsG11(I) and tsG13(I) are more labile than the wild-type protein at the nonp...
Virology, 2003
The fusogenic envelope glycoprotein G of the rhabdovirus vesicular stomatitis virus (VSV) induces membrane fusion at acidic pH. At acidic pH the G protein undergoes a major structural reorganization leading to the fusogenic conformation. However, unlike other viral fusion proteins, the low-pH-induced conformational change of VSV G is completely reversible. As well, the presence of an ␣-helical coiled-coil motif required for fusion by a number of viral and cellular fusion proteins was not predicted in VSV G protein by using a number of algorithms. Results of pH dependence of the thermal stability of G protein as determined by intrinsic Trp fluorescence and circular dichroism (CD) spectroscopy show that the G protein is equally stable at neutral or acidic pH. Destabilization of G structure at neutral pH with either heat or urea did not induce membrane fusion or conformational change(s) leading to membrane fusion. Taken together, these data suggest that the mechanism of VSV G-induced fusion is distinct from the fusion mechanism of fusion proteins that involve a coiled-coil motif.
Journal of virology, 1981
The role of carbohydrate in the morphogenesis of vesicular stomatitis virus was studied, using the antibiotic tunicamycin to inhibit glycosylation. It has been reported previously (Gibson et al., J. Biol. Chem. 254:3600-3607, 1979) that the San Juan strain of vesicular stomatitis virus requires carbohydrate for efficient migration of the glycoprotein (G) to the cell surface and for virion formation, whereas the prototype or Orsay strain of vesicular stomatitis virus is less stringent in its carbohydrate requirement at 30 degrees C. However, there are many differences between the two strains. We found that mutational changes within the G protein of the same strain of virus (prototype or Orsay) alters the requirement for carbohydrate at 30 degrees C. Group V or G protein mutants tsO45 and tsO44, like their prototype parent, did not require carbohydrate for efficient morphogenesis. In contrast, the G protein of another group V mutant, tsO110, was totally dependent upon carbohydrate add...
Localization of two cellular forms of the vesicular stomatitis viral glycoprotein
Journal of virology, 1977
Two cell-associated forms of the glycoprotein (G) of vesicular stomatitis virus, termed G1 and G2, have been resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. G1 has the higher electrophoretic mobility, but both forms migrate more slowly than G protein synthesized in a wheat germ cell-free system (G0), which presumably is the unglycosylated form. G1 is a kinetic precursor of the G2 form, and the apparent cause of the electrophoretic difference between the two species is the presence of N-acetylneuraminic acid on the G2 form. Conversion of G1 to G2 occurs 10 to 20 min prior to the appearance of the G2 form of the protein on the cell surface. This suggests that the G protein may be completely glycosylated several minutes prior to its migration to the cell surface and that glycosylation is not the limiting step in its maturation. No glycoprotein comigrating with G0 can be detected in the infected cells, even after 5-min labeling periods; this suggests that partial ...
Journal of Biological Chemistry, 2001
Membrane fusion is the key step in the entry of enveloped animal viruses into their host cells. Fusion of vesicular stomatitis virus with membranes occurs at acidic pH and is mediated by its envelope glycoprotein, the G protein. To study the structural transitions induced by acidic pH on G protein, we have extracted the protein from purified virus by incubation with nonionic detergent. At pH 6.0, purified G protein was able to mediate fusion of either phospholipid vesicles or Vero cells in culture. Intrinsic fluorescence studies revealed that changes in the environment of Trp residues occurred as pH decreases. In the absence of lipidic membranes, acidification led to G protein aggregation, whereas protein-protein interactions were substituted by protein-lipid interactions in the presence of liposomes. 1,1-Bis(4-aniline-5-naphthalene sulfonate) (bis-ANS) binding was utilized to probe the degree of exposure of hydrophobic regions of G protein during acidification. Bis-ANS binding was maximal at pH 6.2, suggesting that a hydrophobic segment is exposed to the medium at this pH. At pH 6.0, a dramatic decrease in bis-ANS binding was observed, probably due to loss of tridimensional structure during the conformational rearrangement. This hypothesis was confirmed by circular dichroism analysis at different pH values, which showed a great decrease in ␣-helix content at pH values close to 6.0, suggesting that a reorganization of G protein secondary structure occurs during the fusion reaction. Our results indicate that G protein undergoes dramatic structural changes at acidic pH and acquires a conformational state able to interact with the target membrane.