Senescence Networking: WRKY18 is an Upstream Regulator, a Downstream Target Gene, and a Protein Interaction Partner of WRKY53
Senescence Networking: WRKY18 is an Upstream Regulator, a Downstream Target Gene, and a Protein Interaction Partner of WRKY53
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DOI：
10.1007/s00344-013-9380-2
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发表时间：
2014-03
影响因子：
4.8
通讯作者：
Maren Potschin;Silke Schlienger;Stefan Bieker;U. Zentgraf
中科院分区：
文献类型：
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作者：
Maren Potschin;Silke Schlienger;Stefan Bieker;U. Zentgraf
转录重编程是衰老调节的中心特征，意味着转录因子的重要作用。植物特有的NAC和WRKY家族中的不同成员已经被认为具有调控功能，在拟南芥中也是如此，在其他植物中也是如此。WRKY53是拟南芥WRKY家族中一个重要的衰老调节因子，在不同水平上受到严格的调控。在这项研究中，我们发现WRKY18，以前被认为是WRKY53在WRKY网络中的下游靶标，也调节着WRKY53的表达。WRKY18能够直接与WRKY53启动子区域的不同W盒结合，并在利用拟南芥原生质体的瞬时转化系统中抑制WRKY53启动子驱动的报告基因的表达。与其对WRKY53的抑制作用一致，WRKY18作为一个正向衰老调节因子，过表达导致衰老延迟，而WRKY18突变植株表现出明显的加速衰老。此外，利用分裂泛素系统在酵母中检测到WRKY53和WRKY18蛋白之间的直接相互作用，并通过FRET-FLIM在车前草瞬时转化的烟草表皮细胞中检测到WRKY53和WRKY18蛋白之间的直接相互作用。与WRKY18/18同源二聚体相比，WRKY18/53异源二聚体对WRKY53启动子驱动的报告基因表达产生了积极的影响，但似乎只作用于较短的1.1kbp启动子片段，而不作用于2.8kbp长的片段，这表明较长的WRKY53启动子上存在更复杂的蛋白质-蛋白质-DNA相互作用，这很可能也是由启动子在染色质水平上的可及性引发的。
Transcriptional reprogramming is a central feature of senescence regulation, implying an essential role for transcription factors. A regulatory function has already been attributed to different members of the plant-specific NAC and WRKY families inArabidopsisbut also in other plant species. WRKY53 is one important senescence regulator of theArabidopsisWRKY family that is tightly regulated on different levels. In this study we show that WRKY18, which was formerly characterized as a downstream target of WRKY53 in the WRKY network, also regulates the expression ofWRKY53. WRKY18 is able to bind directly to different W-boxes in theWRKY53promoter region and to repress expression of aWRKY53promoter-driven reporter gene in a transient transformation system usingArabidopsisprotoplasts. Consistent with its repressing function onWRKY53as a positive senescence regulator,WRKY18overexpression led to delayed senescence, whereaswrky18mutant plants exhibited a clearly accelerated senescence. In addition, a direct interaction between WRKY53 and WRKY18 proteins could be detected in yeast using the split ubiquitin system andin plantain transiently transformed tobacco epidermal cells via FRET-FLIM. In contrast to WRKY18/18 homodimers, WRKY18/53 heterodimers positively influencedWRKY53promoter-driven reporter gene expression but appear to act only on a shorter 1.1 kbp promoter fragment but not on a 2.8 kbp longer fragment, indicating a more complex protein-protein-DNA interaction on the longerWRKY53promoter, most likely also triggered by the accessibility of the promoter on the chromatin level.