Functional characterization of coat protein and V2 involved in cell to cell movement of Cotton leaf curl Kokhran virus-Dabawali

The functional attributes of coat protein (CP) and V2 of the monopartite begomovirus, Cotton leaf curl Kokhran virus- Dabawali were analyzed in vitro and in vivo by their overexpression in E. coli, insect cells and transient expression in the plant system. Purified recombinant V2 and CP proteins were shown to interact with each other using ELISA and surface plasmon resonance. Confocal microscopy of Sf21 cells expressing V2 and CP proteins revealed that V2 localized to the cell periphery and CP to the nucleus. Deletion of the N terminal nuclear localization signal of CP restricted its distribution to the cytoplasm. GFP-V2 and YFP-CP transiently expressed in N. benthamiana plants by agroinfiltration substantiated the localization of V2 to the cell periphery and CP predominantly to the nucleus. Interestingly, upon coinfiltration, CP was found both in the nucleus and in the cytoplasm along with V2. These results suggest that the interaction of V2 and CP may have important implications in the cell to cell movement.