Studies on Plant-Pathogen Interactions Using Activity-based Proteomics

To accelerate functional annotation of proteins with a role during plant-pathogen interactions it is essential to monitor activities of proteins rather than the abundance of transcripts and proteins, since many proteins are posttranslationally regulated during antagonistic interactions. Activity-based protein profiling (ABPP) displays the active proteome using small molecule probes that react with the active site of proteins in an activity-dependent manner. ABPP is a simple and powerful functional proteomics approach that has made important contributions to studies on immune responses and plant-pathogen interactions. ABPP revealed up-regulated proteasome activities during immune responses, and displayed differential serine hydrolase activities of both host and pathogen during infection. Furthermore, ABPP in the presence of putative inhibitors demonstrated that pathogens from different kingdoms produce effectors that suppress different proteolytic activities of the host. Taken together, these examples show that ABPP is a simple and robust way to capture functional information beyond standard proteomic techniques.