Determination of the molecular mechanism of cell-to-cell movement in squash leaf curl geminivirus

The intercellular spread of plant viruses is an essential process with extensive implications for the life cycle of the virus, and the cell biology of the host. In all plant viruses, intercellular spread is accomplished by a special class of viral encoded protein, termed movement proteins (MPs). The work of this thesis is the study of the MPs of squash leaf curl geminivirus. Unlike most plant viruses, which replicate in the cytoplasm of infected cells, geminiviruses have genomes of DNA, and must replicate in the nucleus. Thus, the nuclear membrane poses an additional barrier to cell-to-cell spread. To overcome this block, I propose that SqLCV encodes two MPs: a nuclear shuttle (BR1) to transport the ssDNA progeny as a BR1:ssDNA complex between the nuclear and cytoplasmic compartments; and a second MP (BL1) which functions to transport the BR1:ssDNA complexes across the cell wall into adjacent cells. I will show that this movement is coordinated through specific protein:protein interactions between the two MPs in a process which provides directionality to movement. Further, I will delimit the regions (domains) in each MP which are responsible for the functions of subcellular targeting and protein:protein interaction. Finally, I will discuss the potential for post-translational phosphorylation in regulating subcellular targeting and interaction between the MPs.U of I OnlyETDs are only available to UIUC Users without author permissio