An as-1-like motif controls the level of expression of the gene for the pathogenesis-related protein 1a from tobacco
An as-1-like motif controls the level of expression of the gene for the pathogenesis-related protein 1a from tobacco
复制标题
类似as-1的基序控制烟草发病机制相关蛋白1a的基因表达水平
作者：
Georg Strompen;R. Grüner;U. Pfitzner
组1（PR-1）的致病相关蛋白在植物中被病原体攻击、将植物暴露于（乙酰）水杨酸（阿萨，SA）和发育线索强烈诱导。对PR-1a启动子的功能分析鉴定了一个139 bp（从-691到-553）的区域，该区域介导响应阿萨的GUS报告基因的表达。该区域的检查揭示了两个TGACG元件，使人想起激活序列-1（as-1）。最近，据报道as-1在CaMV 35 S RNA启动子的背景下对SA有反应。为了解决的问题，是否作为-1-样序列可能是PR-1a基因的表达的功能意义，凝胶迁移试验进行了与TGA 1a，蛋白质已被证明与作为-1在体外相互作用。发现TGA 1a以与as-1相似的特异性和亲和力结合PR-1a as-1样序列。此外，在诱导型906 bp PR-1a启动子的背景下，在as-1样序列中引入突变，该启动子在体外结合TGA 1a时受损。与野生型PR-1a启动子相比，在转基因烟草植物中响应于所有刺激的突变启动子区域获得了显著降低水平的GUS报告基因活性。然而，突变的as-1样序列并没有取消诱导报告基因的表达。两者合计，这些结果表明，烟草PR-1a基因的表达水平是由PR-1a上游区域中的as-1样序列基序控制的，可能与TGA 1a相关因子相互作用。
Pathogenesis-related proteins of group 1 (PR-1) are strongly induced in plants by pathogen attack, exposure of the plants to (acetyl)salicylic acid (ASA, SA), and by developmental cues. Functional analysis of the PR-1a promoter identified a region of 139 bp (from -691 to -553) mediating expression of the GUS reporter gene in response to ASA. Inspection of this region revealed two TGACG elements reminiscent of activation sequence-1 (as-1). Recently, as-1 has been reported to be responsive to SA in the context of the CaMV 35S RNA promoter. To address the question of whether the as-1-like sequence may be of functional significance for the expression of the PR-1a gene, gel shift assays were performed with TGA1a, a protein been shown to interact with as-1 in vitro. TGA1a was found to bind to the PR-1a as-1-like sequence with similar specificity and affinity as to as-1. Furthermore, mutations were introduced in the as-1-like sequence in the context of the inducible 906 bp PR-1a promoter which are impaired in binding TGA1a in vitro. Significantly reduced levels of GUS reporter gene activity were obtained with the mutant promoter regions as compared to the wild-type PR-1a promoter in response to all stimuli in transgenic tobacco plants. Yet, mutation of the as-1-like sequence did not abolish induction of reporter gene expression. Taken together, these results suggest that the level of expression of the tobacco PR-1a gene is controlled by an as-1-like sequence motif in the PR-1a upstream region, possibly interacting with a factor related to TGA1a.