Rook F, Gerrits N, Kortstee A, van Kampen M, Borrias M, Weisbeek P, Smeekens S
Department of Molecular Cell Biology, Utrecht University, The Netherlands.
Plant J. 1998 Jul;15(2):253-63. doi: 10.1046/j.1365-313x.1998.00205.x.
The Arabidopsis bZIP transcription factor gene ATB2 has been shown previously to be expressed in a light-regulated and tissue-specific way. Here we describe the precise localization of ATB2 expression, using transgenic lines containing an ATB2 promoter-GUS reporter gene construct. The observed expression pattern suggests a role for ATB2 in the control of processes associated with the transport or utilization of metabolites. Remarkably, expression of the ATB2-GUS reporter gene construct was specifically repressed by sucrose. Other sugars, such as glucose and fructose, alone or in combination, were ineffective. Repression was observed at external sucrose concentrations exceeding 25 mM. Transcript levels of both the endogenous ATB2 gene and the ATB2-GUS reporter gene were not repressed by sucrose, suggesting that sucrose affects mRNA translation. This translational regulation involves the ATB2 leader sequence because deletion of the leader resulted in loss of sucrose repression. Our results provide evidence for a sucrose-specific sugar sensing and signalling system in plants.
拟南芥bZIP转录因子基因ATB2此前已被证明以光调节和组织特异性的方式表达。在此，我们利用含有ATB2启动子-GUS报告基因构建体的转基因株系，描述了ATB2表达的精确定位。观察到的表达模式表明ATB2在与代谢物运输或利用相关的过程控制中发挥作用。值得注意的是，ATB2-GUS报告基因构建体的表达受到蔗糖的特异性抑制。其他糖类，如葡萄糖和果糖，单独或组合使用均无效。在外部蔗糖浓度超过25 mM时观察到抑制作用。内源性ATB2基因和ATB2-GUS报告基因的转录水平均未受到蔗糖的抑制，这表明蔗糖影响mRNA翻译。这种翻译调控涉及ATB2前导序列，因为前导序列的缺失导致蔗糖抑制作用丧失。我们的结果为植物中蔗糖特异性的糖感知和信号系统提供了证据。
