A Critical Role for the TIFY Motif in Repression of Jasmonate Signaling by a Stabilized Splice Variant of the JASMONATE ZIM-Domain Protein JAZ10 in Arabidopsis
A Critical Role for the TIFY Motif in Repression of Jasmonate Signaling by a Stabilized Splice Variant of the JASMONATE ZIM-Domain Protein JAZ10 in Arabidopsis
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DOI：
10.1105/tpc.108.064097
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发表时间：
2009-01-01
期刊：
影响因子：
11.6
通讯作者：
Howe, Gregg A.
中科院分区：
文献类型：
--
作者：
Chung, Hoo Sun;Howe, Gregg A.
茉莉酸ZIM结构域（JAZ）蛋白作为茉莉酸（JA）信号传导的阻遏物。F - 盒蛋白冠菌素不敏感蛋白1（COI1）对具有生物活性的茉莉酸的感知会通过泛素 - 蛋白酶体途径导致JAZ蛋白降解，这反过来又激活了参与植物生长、发育和防御的基因的表达。JAZ蛋白包含两个高度保守的序列区域：与COI1相互作用使阻遏物不稳定的Jas结构域以及功能未知的ZIM结构域。在此，我们表明ZIM结构域内保守的TIFY基序（TIFF/YXG）介导了大多数拟南芥JAZ蛋白之间的同源和异源相互作用。我们还鉴定出了JAZ10的一种可变剪接形式（JAZ10.4），它缺少Jas结构域，因此对茉莉酸诱导的降解具有高度抗性。由JAZ10.4过表达所赋予的强烈的茉莉酸不敏感表型可被阻断JAZ10.4 - JAZ相互作用的TIFY基序中的突变所抑制。我们得出结论，JAZ10.4在茉莉酸存在的情况下起到减弱信号输出的作用，并进一步表明这种剪接变体的显性负作用涉及通过ZIM/TIFY结构域的蛋白质 - 蛋白质相互作用。JAZ10.4与MYC2相互作用的能力与一个模型相符，在该模型中，包含JAZ10.4的蛋白质复合物直接抑制促进茉莉酸响应基因表达的转录因子的活性。
JASMONATE ZIM-domain (JAZ) proteins act as repressors of jasmonate (JA) signaling. Perception of bioactive JAs by the F-box protein CORONATINE INSENSITIVE1 (COI1) causes degradation of JAZs via the ubiquitin-proteasome pathway, which in turn activates the expression of genes involved in plant growth, development, and defense. JAZ proteins contain two highly conserved sequence regions: the Jas domain that interacts with COI1 to destabilize the repressor and the ZIM domain of unknown function. Here, we show that the conserved TIFY motif (TIFF/YXG) within the ZIM domain mediates homo-and heteromeric interactions between most Arabidopsis thaliana JAZs. We have also identified an alternatively spliced form (JAZ10.4) of JAZ10 that lacks the Jas domain and, as a consequence, is highly resistant to JA-induced degradation. Strong JA-insensitive phenotypes conferred by overexpression of JAZ10.4 were suppressed by mutations in the TIFY motif that block JAZ10.4 -JAZ interactions. We conclude that JAZ10.4 functions to attenuate signal output in the presence of JA and further suggest that the dominant-negative action of this splice variant involves protein -protein interaction through the ZIM/TIFY domain. The ability of JAZ10.4 to interact with MYC2 is consistent with a model in which a JAZ10.4-containing protein complex directly represses the activity of transcription factors that promote expression of JA response genes.