The arabidopsis CORONATINE INSENSITIVE1 protein is a jasmonate receptor

Abstract

Jasmonates play a number of diverse roles in plant defense and development. CORONATINEINSENSITIVE1 (COM), an F-box protein essential for all the jasmonate responses, interacts with multiple proteins to form the SCFco41 E3 ubiquitin ligase complex and recruits jasmonate ZIM-domain (JAZ) proteins for degradation by the 26S proteasome. To determine which protein directly binds to jasmonoyl-isoleucine (JA-lle)/coronatine (COR) and serves as a receptor for jasmonate, we built a high-quality structural model of COM and performed molecular modeling of COM-jasmonate interactions. Our results imply that COM has the structural traits for binding JA-IIe or COR. The direct binding of these molecules with COM was further examined using a combination of molecular and biochemical approaches. First, we used the immobilized jasmonate approach to show that the COM protein in crude leaf extracts can bind to the jasmonate moiety of JA-IIe. Second, we employed surface plasmon resonance technology with purified COM and JAZ1 protein to reveal the interaction among COM, JA-IIe, and JAZ1. Finally, we used the photoaffinity labeling technology to show the direct binding of COR with purified insect-expressed COM. Taken together, these results demonstrate that COM directly binds to JA-IIe and COR and serves as a receptor for jasmonate. © 2009 American Society of Plant Biologists.