INTERACTION BETWEEN TUBULIN AND THE VIRAL MATRIX PROTEIN OF VESICULARSTOMATITIS-VIRUS - POSSIBLE IMPLICATIONS IN THE VIRAL CYTOPATHIC EFFECT

The matrix (M) protein of vesicular stomatitis virus has been shown to induce the rounding of cells. Experiments were performed in order to define the mechanism by which M protein could cause this cytopathic ef fect (CPE). Immunofluorescence experiments performed on infected cells indicate that cellular rounding coincides with the disruption of the microtubular network. Immunoprecipitation of M protein or tubulin in i nfected cell extract demonstrates an association of these two proteins in vivo. We show that M protein is capable of interacting in vitro wi th tubulin in both its polymerized and nonassembled forms. Studies usi ng proteolytically cleaved proteins indicate that this interaction occ urs via the highly basic N-terminal domain of M protein and the highly acidic C-terminal region of tubulin. Furthermore, a thermosensitive m utant (tsG33) containing a mutation in the matrix protein gene which i s unable to induce CPE at nonpermissive temperature interacts with tub ulin with a lower affinity. These results demonstrate that M protein i nteracts with tubulin in vivo and in vitro and strongly suggest that C PE is caused by this interaction. (C) 1994 academic Press, Inc.