Membrane interactions of plant virus movement proteins

Abstract

Plant viruses post a significant risk to both global food security, and industrial agriculture, however very little is known regarding their molecular mechanisms. Despite intensive study since the discovery of a multitude of plant virtual movement proteins, it remains unknown how they transverse the plasmodesmata, and thus move between cells. The CMV virus is widespread, infecting over a thousand plant species, and yet the means by which the movement protein CMV 3a associates to cellular membranes, targets itself and viral genomes to plasmodesmata have not been described. This study initially attempted to purify the CMV 3a protein from bacterial expression for structural and biophysical studies to examine viral protein and host membrane interactions. The study also began mapping the CMV 3a protein surface to investigate protein localisation and membrane attachment in planta, identifying structural features, including two potentially amphipathic helices which bear further investigation for potential roles in membrane association. Finally, this thesis examined the potential for the lipid modification S-acylation (Palmitoylation) as a membrane anchor, across a range of viral movement proteins. Describing this modification of viral movement proteins for the first time, S-acylation was demonstrated to not only be widespread, but potentially play different roles across a range of plant virus movement systems. This information is vital for the advancement of the field’s understanding of the cell to cell movement of plant viruses, and the potential development of control strategies; and hence the safeguarding of global food security.