Our overall goal in this project is understand how particular P. syringae type III effector proteins have evolved to manipulate plant signaling machinery. Our rationale is that by understanding how a collection of pathogen virulence factors act inside the host cell, we will better understand the normal, defense relevant function of their targets. Our approach is a combination of structural biology, genetics and plant-pathology. Our work, and the work of other labs dissecting similar systems in plant pathology, has led to a broad coalescence of knowledge relevant to both plant and animal health. This work fits the DOE remit in understanding how the structure of the plant cell works as an energy producing factory. Of particular interest to this DOE Program, our work “combines experimental and computational tools from the physical sciences with biochemistry and molecular biology” and addresses a problem that will vex Biofuels production, namely pathogens usurping plant energy to their benefit and to the detriment of their plant hosts.  

Our DOE funded project to date has focused on the mode of action of the AvrRpm1 and AvrB type III effectors, and their interaction with a host protein called RIN4. For this renewal, we intend to broaden our use of structural biology to help us understand the function of the HopAF1 and HopH1 type III effector protein families, for which we have reasonable hypotheses regarding their biochemical functions and the host proteins with which they interact. We will investigate plausible functions for using similar overall approaches that have served us well to date: Site specific mutagenesis followed by both in vivo tests of effector function and in vitro tests for the presumed biochemical function. In parallel, we will avail ourselves of the UNC-CH crystallography core to determine the structures of both free type III effectors and each effector bound to its proposed (or, better, proven) target.