Ditzer Andrea, Bartels Dorothea
Institute of Molecular Physiology and Biotechnology of Plants (IMBIO), University of Bonn, Kirschallee 1, D-53115 Bonn, Germany.
Plant Mol Biol. 2006 Jul;61(4-5):643-63. doi: 10.1007/s11103-006-0038-3.
The resurrection plant Craterostigma plantagineum (Scrophulariaceae) is used as a model system to investigate the molecular and biochemical basis of desiccation tolerance. Genes which contribute to desiccation tolerance are expressed during dehydration of this plant. One of the dehydration-induced genes is CpC2, a group 4 LEA gene. The CpC2 promoter was analysed and a core promoter region (CPR) was identified which is critical for the responsiveness of the gene to dehydration and the plant hormone ABA. The CPR motif contains two ABA-response elements (ABRE) and a binding site for HDZIP transcription factors. A yeast one-hybrid screen was performed to isolate CPR binding proteins. This resulted in the isolation of a bZIP transcription factor (CpbZIP1) and three highly conserved CpHistone H3 proteins. Two of these CpHistone H3 proteins are constitutively expressed histone H3 variants which are suggested to be involved in gene regulation via histone modification. The CpbZIP1 belongs to the group S of bZIP genes which possess long 5'-UTRs with a putative regulatory function. A second very similar bZIP clone, CpbZIP2, was isolated which contains a conserved small upstream open reading frame (uORF) within the 5'-leader sequence. A possible regulatory role of the uORF is discussed.
复苏植物车前叶蓝蓟（玄参科）被用作研究耐脱水分子和生化基础的模型系统。有助于耐脱水的基因在该植物脱水过程中表达。其中一个脱水诱导基因是CpC2，一种第4组LEA基因。对CpC2启动子进行了分析，并鉴定出一个核心启动子区域（CPR），该区域对于基因对脱水和植物激素脱落酸（ABA）的响应至关重要。CPR基序包含两个ABA响应元件（ABRE）和一个HDZIP转录因子结合位点。进行了酵母单杂交筛选以分离CPR结合蛋白。这导致分离出一个bZIP转录因子（CpbZIP1）和三种高度保守的Cp组蛋白H3蛋白。其中两种Cp组蛋白H3蛋白是组成型表达的组蛋白H3变体，提示它们通过组蛋白修饰参与基因调控。CpbZIP1属于bZIP基因的S组，其具有具有推定调控功能的长5'-非翻译区（UTR）。分离出了第二个非常相似的bZIP克隆CpbZIP2，其在5'-前导序列内包含一个保守的小上游开放阅读框（uORF）。讨论了uORF可能具有调节作用。
