Our work on the PYR/PYL protein family has shown that these proteins bind to PP2Cs in response to (+)-ABA and synthetic ABA agonists, such as pyrabactin and (-)-ABA. The PYR/PYLs play a major role in controling which ligands induce an ABA response in this new receptor system. For example, multiple PYR/PYLs respond to (+)-ABA, the naturally occuring form of ABA but it appears that only PYR1 is necessary for pyrabactin action in vivo. Thus, our work shows that PYR/PYLs play critical roles in controling the selectivity of agonist action. In this context, we are determining the structure of ABA agonists bound to PYR1 and other PYLs to understand the mechanims of ABA perception and to design improved agonists and receptors for agricultural uses. This work is the result of a very productive collaboration with the laboratory of Dr. Brian Volkman. Brian's lab solved the structure of the Arabidopsis protein MLP28, a START protein that is related to PYR1. We are also collaborating with Dr. Chia-en Chang's lab. Chia-en is an expert in computational studies of ligand-protein interactions and will soon be a neighbor in the new IIGB genomics building. I will update this post as more data becomes available, but check out the image above. If you would like more information about the status of this project, contact Sean for more details.