Analysis of the function of plant specific CCMC-type glutaredoxins that interact with the bZIP transcription factors of the TGA family

阐明植物对病原体的防御策略是一个重要的研究领域。在防御反应过程中，细胞内氧化还原状态发生了剧烈的变化，并描述了重要调节蛋白的氧化还原控制。Glutaredoxins （GRXs）是一种大约12 kDa的小蛋白质，能够催化分子内或分子间二硫桥或谷胱甘肽（GSH）混合二硫的还原。拟南芥基因组编码30个GRX基因，根据其氧化还原活性中心的氨基酸序列可分为三大类。所有以CCMC基元为特征的7种glutaredoxins都与TGA家族的bZIP转录因子相互作用，后者是水杨酸诱导的植物防御反应“系统性获得性抗性（SAR）”的重要信号成分。这些与TGA相互作用的glutaredoxins在植物防御反应中的功能作用似乎是可能的，因为当植物受到SA处理时，TGA转录因子的一个亚组会发生氧化还原变化。此外，NPR1的关键半胱氨酸在诱导条件下减少，NPR1是一种与TGA因子相互作用的锚蛋白重复蛋白，是SAR建立所必需的。三种与tga相互作用的glutaredo毒素的表达是sa诱导的。我们最近发现GRX/TGA复合物参与了SA和茉莉酸之间的负串扰。该项目的目的是阐明sa诱导的、tgi相互作用的glutaredoxin家族成员的功能。我们将讨论植物防御反应中的一个重要的调控原则，包括调控蛋白的氧化还原修饰机制。

The elucidation of plant defense strategies against pathogens constitutes an important area of research. In the course of the defense reaction, the intracellular redox state changes dramatically and redox control of important regulatory proteins have been described. Glutaredoxins (GRXs) are small proteins of approximately 12 kDa that are able to catalyze the reduction of intra- or intermolecular disulfide bridges or glutathione (GSH) mixed disulfides. The Arabidopsis genome encodes 30 GRX genes that have been classified into three major groups according to the amino acid sequence in their redox active center. All the seven glutaredoxins that are characterized by a CCMC motif interact with the bZIP transcription factors of the TGA family which are important signalling components of the salicylic acid (SA)- inducible plant defense response “systemic acquired resistance (SAR)”. A functional role for these TGA-interacting glutaredoxins in plant defense responses seems likely, as a subgroup of TGA transcription factors is subject to redox changes when plants are treated with SA. In addition, critical cysteines of NPR1, an ankyrin repeat protein that interacts with TGA factors and that is indispensable for SAR establishment, are reduced under inducing conditions. Expression of three of the TGA-interacting glutaredoxins is SA-inducible. We have recently shown that a GRX/TGA complex is involved the negative cross-talk between SA and jasmonic acid. The aim of the project is to elucidate the function of the SA-inducible, TGAinteracting members of the glutaredoxin family. We will address an important regulatory principle in plant defense responses that involves the poorly understood mechanisms of redox modifications of regulatory proteins.