The movement protein of barley yellow dwarf virus-GAV self-interacts and forms homodimers in vitro and in vivo

The 17-kDa movement protein (MP) of the GAV strain of barley yellow dwarf virus (BYDV-GAV) can bind the viral RNA and target to the nucleus. However, much less is known about the active form of the MP in planta. In this study, the ability of the MP to self-interact was analyzed by yeast two-hybrid assay and bimolecular fluorescence complementation. The BYDV-GAV MP has a strong potential to self-interact in vitro and in vivo, and self-interaction was mediated by the N-terminal domain spanning the second alpha-helix (residues 17-39). Chemical cross-linking and heterologous MP expression from a pea early browning virus (PEBV) vector further showed that MP self-interacts to form homodimers in vitro and in planta. Interestingly, the N-terminal domain necessary for MP self-interaction has previously been identified as important for nuclear targeting. Based on these findings, a functional link between MP self-interaction and nuclear targeting is discussed.