Sorting of the respiratory syncytial virus matrix protein into detergent-resistant structures is dependent on cell-surface expression of the glycoproteins.
The interaction of the respiratory syncytial virus (RSV) Matrix (M) protein with the plasma membrane was investigated using polyclonal and monoclonal antisera raised against recombinant M expressed in bacteria. M bound mainly to the plasma membrane, although a significant proportion bound to internal membranes. However, no localisation of M with the Golgi was observed, suggesting that transport of M to the plasma membrane was independent of the transport mechanism for the viral glycoproteins. Expression from a recombinant baculovirus demonstrated the ability of M to bind membranes in the absence of viral glycoprotein expression. When cell-surface expression of the viral glycoproteins was prevented using Brefeldin A, M was still found in association with the plasma membrane, but the characteristics of M's membrane-binding ability were different to that found in untreated infected cells. In the presence of normal glycoprotein expression, M was sorted into lipid rafts and, in addition, formed structures that could only be disrupted by treatment with high salt buffers, a feature suggesting an interaction with the cytoskeleton or the formation of strong intramolecular associations. Brefeldin A prevented M from being sorted into lipid rafts or from forming strong intramolecular associations. Brefeldin A also affected the stability of M bound to the plasma membrane, as M was more readily dissociated in the presence of the inhibitor. Coexpression of M and F resulted in the incorporation of M into lipid rafts but did not cause the formation of the strong intramolecular bonds, suggesting that additional factors are required for this phenomena.
D000818:Animals; D020126:Brefeldin A / Q000494:pharmacology; D002462:Cell Membrane / Q000378:metabolism*; D003902:Detergents / Q000494:pharmacology; D006801:Humans; D008562:Membrane Glycoproteins / Q000502:physiology*; D021962:Membrane Microdomains / Q000737:chemistry; D051379:Mice; D008807:Mice, Inbred BALB C; D014759:Viral Envelope Proteins / Q000502:physiology*; D014763:Viral Matrix Proteins / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D014764:Viral Proteins / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism
D003902:Detergents; D008562:Membrane Glycoproteins; D014759:Viral Envelope Proteins; D014763:Viral Matrix Proteins; D014764:Viral Proteins; D020126:Brefeldin A