THE CAPSID PROTEIN OF TOMATO YELLOW LEAF CURL VIRUS BINDS COOPERATIVELY TO SINGLE-STRANDED-DNA

The capsid protein (CP) of tomato yellow leaf curl virus (TYLCV) is th e only known component of the virus coat. Here, we identify TYLCV CP a s a single-stranded (ss) DNA binding protein. Purified TYLCV CP bound ssDNA in a highly cooperative and sequence-nonspecific fashion. TYLCV CP-ssDNA complexes were resistant to nucleolytic digestion and remaine d stable at relatively high salt concentrations. Because TYLCV CP is k nown to contain an active nuclear targeting signal, we propose that it s association with the viral genomic ssDNA mediates TYLCV entry into t he host cell nucleus during the infection process.