Kiełbowicz-Matuk Agnieszka, Czarnecka Jagoda, Banachowicz Ewa, Rey Pascal, Rorat Tadeusz
Institute of Plant Genetics, Polish Academy of Sciences, Strzeszyńska 34, 60-479, Poznań, Poland.
Molecular Biophysics Department, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614, Poznań, Poland.
Plant Cell Environ. 2017 Mar;40(3):424-440. doi: 10.1111/pce.12875. Epub 2017 Jan 27.
ZPR1 proteins belong to the C4-type of zinc finger coordinators known in animal cells to interact with other proteins and participate in cell growth and proliferation. In contrast, the current knowledge regarding plant ZPR1 proteins is very scarce. Here, we identify a novel potato nuclear factor belonging to this family and named StZPR1. StZPR1 is specifically expressed in photosynthetic organs during the light period, and the ZPR1 protein is located in the nuclear chromatin fraction. From modelling and experimental analyses, we reveal the StZPR1 ability to bind the circadian DNA cis motif 'CAACAGCATC', named CIRC and present in the promoter of the clock-controlled double B-box StBBX24 gene, the expression of which peaks in the middle of the day. We found that transgenic lines silenced for StZPR1 expression still display a 24 h period for the oscillation of StBBX24 expression but delayed by 4 h towards the night. Importantly, other BBX genes exhibit altered circadian regulation in these lines. Our data demonstrate that StZPR1 allows fitting of the StBBX24 circadian rhythm to the light period and provide evidence that ZPR1 is a novel clock-associated protein in plants necessary for the accurate rhythmic expression of specific circadian-regulated genes.
ZPR1蛋白属于动物细胞中已知的C4型锌指协调蛋白，可与其他蛋白相互作用并参与细胞生长和增殖。相比之下，目前关于植物ZPR1蛋白的了解非常有限。在此，我们鉴定出一种属于该家族的新型马铃薯核因子，并将其命名为StZPR1。StZPR1在光照期于光合器官中特异性表达，且ZPR1蛋白定位于核染色质组分中。通过建模和实验分析，我们揭示了StZPR1能够结合昼夜节律DNA顺式基序“CAACAGCATC”（命名为CIRC），该基序存在于生物钟控制的双B-box基因StBBX24的启动子中，其表达在一天的中午达到峰值。我们发现，沉默StZPR1表达的转基因株系中，StBBX24表达的振荡仍具有24小时的周期，但向夜间延迟了4小时。重要的是，这些株系中的其他BBX基因表现出昼夜节律调控的改变。我们的数据表明，StZPR1使StBBX24的昼夜节律与光照期相匹配，并提供证据表明ZPR1是植物中一种新型的与生物钟相关的蛋白，对于特定昼夜节律调控基因的准确节律性表达是必需的。
