CONSTITUTIVE, LIGHT-RESPONSIVE AND CIRCADIAN CLOCK-RESPONSIVE FACTORS COMPETE FOR THE DIFFERENT L-BOX ELEMENTS IN PLANT LIGHT-REGULATED PROMOTERS
CONSTITUTIVE, LIGHT-RESPONSIVE AND CIRCADIAN CLOCK-RESPONSIVE FACTORS COMPETE FOR THE DIFFERENT L-BOX ELEMENTS IN PLANT LIGHT-REGULATED PROMOTERS
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DOI：
10.1046/j.1365-313x.1993.04040611.x
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发表时间：
1993-10-01
期刊：
影响因子：
7.2
通讯作者：
GIULIANO, G
中科院分区：
文献类型：
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作者：
BORELLO, U;CECCARELLI, E;GIULIANO, G
I盒是一个保守的调控基序，存在于植物基因（rbcS，cab和nia）的上游，其转录受光和生物钟的调控。用凝胶阻滞和紫外交联法分离了番茄核提取物中的两组IBFs：第一组IBF-1识别光响应rbcS启动子的I盒;该组中的一种因子IBF-1a也识别相邻的G盒，其先前已显示结合不同种类的植物转录因子，G盒结合因子（GBF）在实验分辨率的限制下，IBF-1a和GBF竞争G盒上的相同核苷酸。然而，这两种活动在生物化学和免疫学上是不同的。第二组因子（IBF-2）识别nia启动子的I盒，该启动子受光和生物钟调节;该组中的一个因子IBF-2a也结合第二个启动子（cab启动子）的I盒，该启动子显示类似的调节。在cab和nia启动子上的IBF-2a结合位点与来自小麦的生物钟响应启动子元件显示出广泛的同源性。IBF-2a的丰度是昼夜调节的，并在光照期开始时显示出显著的诱导作用。植物在连续黑暗中的转移表明，这种诱导是在生物钟的控制下。这些数据表明，I盒结合因子可能参与调控转录光和昼夜节律钟。
The I box is a conserved regulatory motif which is found upstream of plant genes (rbcS, cab and nia) whose transcription is regulated by light and the circadian clock. Gel retardation and UV cross-linking assays were used to resolve two different groups of I box binding factors (IBFs) in tomato nuclear extracts.Active components of the first group (IBF-1) recognize the I box of the light-responsive rbcS promoter; one factor within this group, IBF-1a, also recognizes the adjacent G box, which has been shown previously to bind a different class of plant transcription factors, the G box binding factors (GBFs). To the limit of experimental resolution, IBF-1a and GBF compete for the same nucleotides on the G box. Nevertheless, these two activities are biochemically and immunologically distinct. The relative abundance of IBF-1a shows a vast decrease in dark-adapted plants.Factors in the second group (IBF-2), recognize the I box of the nia promoter, which is regulated both by light and the circadian clock; one factor within this group, IBF-2a, also binds the I box of a second promoter showing similar regulation, the cab promoter. The IBF-2a binding sites on the cab and nia promoters show extensive homology to a circadian clock-responsive promoter element from wheat. The abundance of IBF-2a is diurnally regulated and shows a dramatic induction around the onset of the light period. Transfer of the plants in continuous darkness demonstrates that this induction is under the control of a circadian clock. These data suggest that I box binding factors may be involved in regulation of transcription by light and the circadian clock.