Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education; School of Life Sciences, Shandong University, Jinan, 250100, China; College of Life Science, Qufu Normal University, Qufu, 273165, China.
J Integr Plant Biol. 2015 Feb;57(2):162-70. doi: 10.1111/jipb.12308. Epub 2015 Jan 13.
Bidirectional promoters are relatively abundant in eukaryotic genomes, suggesting that they have an important biological significance. As yet, few of these promoters have been characterized in detail. Here, using a promoter::GUS transgene approach has revealed that the intergenic region of Arabidopsis thaliana divergent genes At1g71850 and At1g71860 is an asymmetric bidirectional promoter, which exhibits an orientation-dependent expression profile. The strength of the forward promoter was greater than that of the reverse promoter, and their tissue specificities were not identical. Deletion analyses revealed that this bidirectional promoter could be divided into three functional regions. The basal level and tissue specificity of the promoter in the reverse orientation were regulated positively by region II and negatively by region III, whereas promoter activity in the forward orientation was regulated negatively by region II and positively by region I. Thus the 52-bp stretch of region II had a dual function, enhancing expression in the reverse orientation and suppressing it in the forward orientation. These results demonstrated that the activity of the At1g71850-At1g71860 bidirectional promoter was modulated by complex interactions between both positive and negative cis-acting elements. These findings will enhance our understanding of the regulatory mechanisms of plant bidirectional promoters.
双向启动子在真核生物基因组中相对丰富，这表明它们具有重要的生物学意义。然而，这些启动子中很少有被详细描述。在这里，使用启动子::GUS 转基因方法揭示了拟南芥 divergen 基因 At1g71850 和 At1g71860 的基因间区是一个不对称的双向启动子，它表现出依赖于方向的表达模式。正向启动子的强度大于反向启动子的强度，它们的组织特异性也不完全相同。缺失分析表明，这个双向启动子可以分为三个功能区域。反向方向启动子的基础水平和组织特异性受到区域 II 的正向调控和区域 III 的负向调控，而正向方向启动子的活性受到区域 II 的负向调控和区域 I 的正向调控。因此，区域 II 的 52 个碱基对片段在反向方向上具有双重功能，增强表达，而在正向方向上则抑制表达。这些结果表明，At1g71850-At1g71860 双向启动子的活性是由正、负顺式作用元件之间的复杂相互作用调节的。这些发现将增强我们对植物双向启动子调控机制的理解。
