Interaction of tobamovirus movement proteins with the plant cytoskeleton.

The movement protein of tobacco mosaic tobamovirus and related viruses is essential for the cell-to-cell spread of infection and, in part, determines the host range of the virus. Movement protein (MP) was fused with the jellyfish green fluorescent protein (GFP), and a modified virus that contained this MP:GFP fusion protein retained infectivity. In protoplasts and leaf tissues, the MP:GFP fusion protein was detected as long filaments shortly after infection. Double-labeling fluorescence microscopy suggests that the MP interacts and coaligns with microtubules. The distribution of the MP is disrupted by treatments that disrupt microtubules, but not by cytochalasin B, which disrupts filamentous F-actin. Microtubules may target the MP to plasmodesmata, the intercellular channels that connect adjacent cells.