Biochemical Analysis of the Cell-to-Cell Movement Protein of Cauliflower Mosaic Virus (CaMV)

Viral infection, in terms of cell-to-cell movement, is presently considered to be an active process, mediated by a virus-encoded function called diffusion protein. To achieve this short distance diffusion, the virus or its nucleic acid must cross the pectocellulosic wall separating the infected cell from the neighboring ones. However, the only envisageable paths for this movement are structures called plasmodesmata. P1, the CaMV gene I product, is involved in the cell-to-cell movement of virus in CaMV-infected plants. This protein has been detected in cell walls, in association with plasmodesmata. However, in the case of caulimovirus infection, the structure of the plasmodesmata must be modified for viral particles to move from cell to cell. Because little is know about P1 and how it functions, we decided to expressed CaMV gene I in Saccharomyces cerevisiae and Escherichia coli.