Design, Synthesis And Application Of Photoaffinity Probes Of Jasmonates And Coronafacic Acid-amino Acid Conjugates With Jasmonic-like Activities

Jasmonates (JAs) are a class of plant hormones, which are derived from oxylipin and characterized by a cyclopentanone structure. JAs are indispensable in plant defense responses and aspects of plant growth and development. An Arabidopsis coronatine insensitive1(COI1) gene encodes an F-box protein required for JA-regulated plant fertility and defense. COI1interacts with multiple proteins to form the SCFcI1E3ubiquitin ligase complex, which is required for all JA responses. The SCFcoI1complex recognizes JA transcriptional repressors called jasmonate ZIM-domain (JAZ) proteins and targets them for subsequent degradation by the26S proteasome in the presence of the hormone. In addition, physical interaction of SCFCOI1with the JAZ proteins is promoted by a bioactive isoleucine-conjugated form of jasmonic acid (JA-Ile) or its stereochemical mimic, coronatine (COR). These results suggest that the SCFCOI1-JAZ complex is the site of JA-Ile/COR perception and that COI1is likely to function as a receptor.Activity-based protein profiling (ABPP) is a valuable chemical strategy for the functional proteomics, which utilizes the activity-based probes (ABPs) to specifically label the active proteins, and it makes the tracing, purifying of the target protein and the study of the protein-protein interaction to be reality.The first part of this dissertation is the application of ABPP in the study of JAs receptor. We designed and synthesized a series of photoaffinity probes of jasmonates based on analysis of JAs structure-activity relationships and molecular modeling of the interaction between COI1and JAs. Among them, PACOR exhibited the most significant biological activity in inhibiting root growth, promoting accumulation of JA-responsive proteins, and triggering COI1-JAZ1interaction in Arabidopsis seedlings. Our results had shown that PACOR can bind with COI1directly. It demonstrated that COI1functions as a receptor for JAs.Jasmonoyl-isoleucine(JA-Ile) is a bioactive molecule of Jasmonates. It is essential for the interaction between SCFCOI1and JAZ proteins and perceived by the SCFCOI1-JAZ complex. Recent studies had shown that JA-Ile have several stereoisomers,(+)-7-iso-Jasmonoyl-L-isoleucine is the endogenous bioactive jasmonate. The stereostructure of conjugates of coronafacic acid (CFA) with amino acids (CFA-AAs) is identical to (+)-7-iso-Jasmonoyl-L-isoleucine stereoisomers. In the second part of this dissertation, we designed and synthesized different kinds of conjugates of CFA with amino acids (CFA-AAs). Among them, CFA-Ile exhibited the most significant biological activity. By using the photoaffinity probe of CFA-Ile, we tried to disclose the mechanism of action of CFA-AAs.