Dissection of the one-MegaDalton JAZ1 protein complex.

Jasmonates (JAs) comprise a class of plant-specific hormones that mediate a large variety of processes involved in plant growth, development and defense. Perception of jasmonoyl-isoleucine (JA-Ile), the bioactive amino acid conjugate of JA, initiates the expression of JA-responsive genes through the degradation of the jasmonate ZIM domain (JAZ) repressor proteins and the subsequent release of the transcriptional activator MYC2. By using a tandem affinity purification based approach, we demonstrated that the Groucho/Tup1-type co-repressor TOPLESS (TPL) and TPL-related proteins are connected to the JAZ proteins via an adaptor protein, designated Novel Interactor of JAZ (NINJA). Both NINJA and TPL were shown to function as negative regulators of JA signaling. Here, we provide additional data, demonstrating that JAZ1 incorporates into high-molecular weight (HMW) protein complexes of > 1 MDa and speculate about their composition.