The structural basis of specific protease-inhibitor interactions at the plant-pathogen interface.

Antagonistic host-pathogen interactions offer intriguing insights into coevolutionary processes at the molecular level. Studies on secreted immune proteases from the model plant tomato and their interactions with different unrelated pathogen-derived inhibitors revealed that the inhibitors exhibit a remarkable selectivity towards different host proteases, and that the host proteases accumulate variant residues at the interaction surfaces that interfere with inhibitor binding. Here, we summarize and discuss the recent findings and use structural models to identify the molecular features underpinning protease selectivity. The observed basic principles translate to other examples of secreted immune hydrolases and their putative inhibitors.