Cell Biology of the SYNV matrix protein

One of the major goals of our lab is to characterize the cell biology of plant rhabdoviral matrix proteins. It is presently unknown whether the matrix (M) proteins of rhabdoviruses adapted to a nuclear site of replication and morphogenesis retain the ability to shut off gene expression in a manner similar to that of M proteins of rhabdoviruses that replicate in the cytoplasm, such as the prototypical animal rhabdovirus, Vesicular stomatitis virus. Using the pGD expression vectors, we have examined the ability of SYNV-M to shut off expression of YFP when these proteins were coexpressed in epidermal cells of Nicotiana benthamiana. These studies clearly demonstrated that the SYNV-M protein was able to suppress the accumulation of YFP when these two proteins were coexpressed in the same cell. Remarkably, the M protein was not able to suppress the YFP reporter in the presence of the SYNV-P protein.  The ability of the M protein to shut off reporter gene, and presumably host gene, expression implicates the P protein in the regulation of the activity of the M protein.  Experiments to address the nature of the SYNV-P and SYNV-M interaction are in progress.