Grant: Discovery Grants Program - Individual

It is estimated that food production will need to increase up to 70% by 2050 to sustain future populations. Central to this challenge will be the discovery of sustainable ways to protect crops from disease, including viral infections. The long-term goal of my NSERC research is to understand the role of viral proteases in virus replication and immune evasion, and to use the knowledge gained to develop antiviral strategies for plants and animals. Recently, we have developed the means to generate protein-based inhibitors of viral proteases. The inhibitors are amino acid variants of ubiquitin (UbVs) that bind tightly and specifically to these enzymes. My short-term goal is to generate and characterize UbV inhibitors that block the activity of proteases from a number of pathogenic plant viruses, and to test my hypothesis that transgenic crops that express these UbVs are resilient to viral infection. Obj 1: Biochemical characterization of plant virus proteases and their inhibition by UbVs. Proteases from 7 plant viruses (representing 5 major virus genera) have been targeted for UbV inhibitor development. UbVs that block their activity will be identified from a phage display library of ubiquitin variants. The inhibitory potency of the UbVs will be assessed using in vitro binding assays. Specificity of the UbVs for their target proteases will be assessed by measuring their ability to bind a panel of functionally related plant cell proteases from Arabidopsis thaliana. Obj 2: Structural basis of plant virus protease activity and inhibition by UbVs. Little is known about the structural basis for how plant virus protases participate in virus replication or how they recognize ubiquitin. X-ray structures of the proteases and the complexes they form with UbVs will be determined to elucidate the molecular basis of plant virus proteases activity and their inhibition by UbVs. Obj 3: UbV inhibitor activity in planta: from protoplasts to transgenic plants. UbVs from Obj 1 will be verified for their ability to block protease activity in live plant protoplasts. Those with greatest potency will be used to transform plants for subsequent virus challenge. UbVs against Turnip Yellow Mosaic Virus and Maize Rayado Fino virus proteases are in-hand. Working with plant biologists at U of Manitoba (UM) and the USDA (Fargo, ND), we will determine if UbV expression in Arabidopsis and canola protects these plants from Turnip Yellow Mosaic Virus, and if UbV expression in maize protects against Maize Rayado Fino Virus.  Results from this Obj will test my hypothesis that UbVs protect against viral infection. I propose a strategy that could sustainably protect numerous cash crops from viral disease and thus positively impact global food security. The multidisciplinary nature of the research will be highly engaging for trainees and will allow them to develop a ground breaking technology while they acquire the skills they need to pursue careers in academia, industry or government.