Guiltinan M J, Marcotte W R, Quatrano R S
Department of Biology, University of North Carolina, Chapel Hill 27599-3280.
Science. 1990 Oct 12;250(4978):267-71. doi: 10.1126/science.2145628.
The mechanism by which phytohormones, like abscisic acid (ABA), regulate gene expression is unknown. An activity in nuclear extracts that interacts with the ABA response element (ABRE) from the 5' regulatory region of the wheat Em gene was identified. A complementary DNA clone was isolated whose product is a DNA binding protein (EmBP-1) that interacts specifically with an 8-base pair (bp) sequence (CACGTGGC) in the ABRE. A 2-bp mutation in this sequence prevented binding of EmBP-1. The same mutation reduced the ability of the ABRE to confer ABA responsiveness on a viral promoter in a transient assay. The 8-bp EmBP-1 target sequence was found to be conserved in several other ABA-responsive promoters and in promoters from plants that respond to signals other than ABA. Similar sequences are found in promoters from mammals, yeast, and in the major late promoter of adenovirus. The deduced amino acid sequence of EmBP-1 contains conserved basic and leucine zipper domains found in transcription factors in plants, yeast, and mammals. EmBP-1 may be a member of a highly conserved family of proteins that recognize a core sequence found in the regulatory regions of various genes that are integrated into a number of different response pathways.
植物激素，如脱落酸（ABA），调节基因表达的机制尚不清楚。已在核提取物中鉴定出一种与小麦Em基因5'调控区的ABA反应元件（ABRE）相互作用的活性。分离出一个互补DNA克隆，其产物是一种DNA结合蛋白（EmBP-1），它与ABRE中的一个8碱基对（bp）序列（CACGTGGC）特异性相互作用。该序列中的一个2-bp突变阻止了EmBP-1的结合。在瞬时分析中，相同的突变降低了ABRE赋予病毒启动子ABA反应性的能力。发现8-bp的EmBP-1靶序列在其他几个ABA反应性启动子以及对ABA以外信号作出反应的植物启动子中是保守的。在哺乳动物、酵母的启动子以及腺病毒的主要晚期启动子中也发现了类似序列。EmBP-1推导的氨基酸序列包含在植物、酵母和哺乳动物转录因子中发现的保守碱性和亮氨酸拉链结构域。EmBP-1可能是一个高度保守的蛋白质家族的成员，该家族识别存在于整合到许多不同反应途径中的各种基因调控区的核心序列。
