Getting it together in plant virus movement: cooperative interactions between bipartite geminivirus movement proteins.

To move cell-to-cell and systemically infect the host, plant viruses must cross the barrier posed by the plant cell wall. Plant viruses accomplish this through strategies that alter the architecture of the infected cell, eliminating this barrier through the action of viral-encoded 'movement proteins'. Detailed studies of a number of cytoplasmically replicating viruses suggest that movement proteins interact with components of the cytoskeleton and transport systems of the plant cell to allow passage of progeny into adjacent cells. Recent work on the two movement proteins encoded by the phloem-restricted geminivirus squash leaf curl virus has defined unique aspects of nuclear transport and protein protein interaction in the movement of this nuclear-replicating virus, and suggests that post-translational phosphorylation may be important in the regulation of movement protein function.