Thines Bryan, Katsir Leron, Melotto Maeli, Niu Yajie, Mandaokar Ajin, Liu Guanghui, Nomura Kinya, He Sheng Yang, Howe Gregg A, Browse John
Institute of Biological Chemistry, Washington State University, Pullman, Washington 99164-6340, USA.
Nature. 2007 Aug 9;448(7154):661-5. doi: 10.1038/nature05960. Epub 2007 Jul 18.
Jasmonate and related signalling compounds have a crucial role in both host immunity and development in plants, but the molecular details of the signalling mechanism are poorly understood. Here we identify members of the jasmonate ZIM-domain (JAZ) protein family as key regulators of jasmonate signalling. JAZ1 protein acts to repress transcription of jasmonate-responsive genes. Jasmonate treatment causes JAZ1 degradation and this degradation is dependent on activities of the SCF(COI1) ubiquitin ligase and the 26S proteasome. Furthermore, the jasmonoyl-isoleucine (JA-Ile) conjugate, but not other jasmonate-derivatives such as jasmonate, 12-oxo-phytodienoic acid, or methyl-jasmonate, promotes physical interaction between COI1 and JAZ1 proteins in the absence of other plant proteins. Our results suggest a model in which jasmonate ligands promote the binding of the SCF(COI1) ubiquitin ligase to and subsequent degradation of the JAZ1 repressor protein, and implicate the SCF(COI1)-JAZ1 protein complex as a site of perception of the plant hormone JA-Ile.
茉莉酸酯及相关信号化合物在植物的宿主免疫和发育过程中都起着关键作用，但其信号传导机制的分子细节仍知之甚少。在此，我们鉴定出茉莉酸ZIM结构域（JAZ）蛋白家族成员是茉莉酸信号传导的关键调节因子。JAZ1蛋白可抑制茉莉酸响应基因的转录。茉莉酸处理会导致JAZ1降解，且这种降解依赖于SCF(COI1)泛素连接酶和26S蛋白酶体的活性。此外，在没有其他植物蛋白的情况下，茉莉酰异亮氨酸（JA-Ile）共轭物而非其他茉莉酸衍生物（如茉莉酸、12-氧代植物二烯酸或茉莉酸甲酯）可促进COI1与JAZ1蛋白之间的物理相互作用。我们的研究结果提出了一个模型，其中茉莉酸配体促进SCF(COI1)泛素连接酶与JAZ1阻遏蛋白结合并随后使其降解，并且表明SCF(COI1)-JAZ1蛋白复合物是植物激素JA-Ile的感知位点。
