Thireault Caitlin, Shyu Christine, Yoshida Yuki, St Aubin Brian, Campos Marcelo L, Howe Gregg A
Department of Energy-Plant Research Laboratory, Michigan State University, East Lansing, MI, 48824, USA.
Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824, USA.
Plant J. 2015 May;82(4):669-79. doi: 10.1111/tpj.12841.
JAsmonate ZIM-domain (JAZ) proteins repress the activity of transcription factors that execute responses to the plant hormone jasmonoyl-L-isoleucine (JA-Ile). The ZIM protein domain recruits the co-repressors NINJA and TOPLESS to JAZ-bound transcription factors, and contains a highly conserved TIF[F/Y]XG motif that defines the larger family of TIFY proteins to which JAZs belong. Here, we report that diverse plant species contain genes encoding putative non-TIFY JAZ proteins, including a previously unrecognized JAZ repressor in Arabidopsis (JAZ13, encoded by At3g22275). JAZ13 is most closely related to JAZ8 and includes divergent EAR, TIFY/ZIM, and Jas motifs. Unlike JAZ8, however, JAZ13 contains a Ser-rich C-terminal tail that is a site for phosphorylation. Overexpression of JAZ13 resulted in reduced sensitivity to JA, attenuation of wound-induced expression of JA-response genes, and decreased resistance to insect herbivory. JAZ13 interacts with the bHLH transcription factor MYC2 and the co-repressor TOPLESS but, consistent with the absence of a TIFY motif, neither NINJA nor other JAZs. Analysis of single and higher-order T-DNA insertion jaz null mutants provided further evidence that JAZ13 is a repressor JA signaling. Our results demonstrate that proteins outside the TIFY family are functional JAZ repressors and further suggest that this expansion of the JAZ family allows fine-tuning of JA-mediated transcriptional responses.
茉莉酸ZIM结构域（JAZ）蛋白可抑制转录因子的活性，这些转录因子负责执行对植物激素茉莉酰-L-异亮氨酸（JA-Ile）的响应。ZIM蛋白结构域将共抑制因子NINJA和TOPLESS招募至与JAZ结合的转录因子处，并且包含一个高度保守的TIF[F/Y]XG基序，该基序定义了JAZ所属的更大的TIFY蛋白家族。在此，我们报告不同植物物种含有编码假定的非TIFY JAZ蛋白的基因，包括拟南芥中一个先前未被识别的JAZ阻遏物（JAZ13，由At3g22275编码）。JAZ13与JAZ8关系最为密切，并且包含不同的EAR、TIFY/ZIM和Jas基序。然而，与JAZ8不同的是，JAZ13含有一个富含丝氨酸的C末端尾巴，这是一个磷酸化位点。JAZ13的过表达导致对JA的敏感性降低、伤口诱导的JA响应基因表达减弱以及对昆虫食草作用的抗性降低。JAZ13与bHLH转录因子MYC2和共抑制因子TOPLESS相互作用，但与缺乏TIFY基序一致，它既不与NINJA相互作用，也不与其他JAZ相互作用。对单T-DNA插入和高阶T-DNA插入jaz缺失突变体的分析提供了进一步的证据，表明JAZ13是JA信号传导的阻遏物。我们的结果表明，TIFY家族之外的蛋白质是功能性JAZ阻遏物，并且进一步表明JAZ家族的这种扩展允许对JA介导的转录反应进行微调。
