Rieping M, Fritz M, Prat S, Gatz C
Universität Bielefeld, Lehrstuhl für Genetik, Fakultät für Biologie, Germany.
Plant Cell. 1994 Aug;6(8):1087-98. doi: 10.1105/tpc.6.8.1087.
TGA1a and PG13 constitute a family of tobacco basic leucine zipper (bZIP) proteins that bind to activating sequence-1 (as-1), which is one of the multiple regulatory cis elements of the cauliflower mosaic virus (CaMV) 35S promoter. After truncation of the CaMV 35S promoter down to position -90 (CaMV 35S [-90] promoter), transcription stringently depends on the presence of as-1, which is recognized by nuclear DNA binding proteins called ASF-1. The role of the TGA1a/PG13 bZIP family in the formation of ASF-1 and in transcriptional activation of the CaMV 35S (-90) promoter has not yet been demonstrated in vivo. We constructed transgenic tobacco plants expressing a mutant of potato PG13, which lacks its wild-type DNA binding domain. This mutant acts as a trans-dominant inhibitor of ASF-1 formation and of expression from the CaMV 35S (-90) promoter, showing that PG13 can specifically interact with proteins necessary for these processes. Although we did not observe any other obvious phenotypic changes, these transgenic plants are a potentially valuable tool in identifying whether TGA1a and PG13 are involved in controlling promoters encoded in the plant genome.
TGA1a和PG13构成了烟草碱性亮氨酸拉链（bZIP）蛋白家族，它们可与激活序列-1（as-1）结合，as-1是花椰菜花叶病毒（CaMV）35S启动子多个调控顺式元件之一。将CaMV 35S启动子截短至-90位（CaMV 35S [-90]启动子）后，转录严格依赖于as-1的存在，as-1可被称为ASF-1的核DNA结合蛋白识别。TGA1a/PG13 bZIP家族在ASF-1形成以及CaMV 35S（-90）启动子转录激活中的作用尚未在体内得到证实。我们构建了表达马铃薯PG13突变体的转基因烟草植株，该突变体缺乏其野生型DNA结合结构域。此突变体作为ASF-1形成和CaMV 35S（-90）启动子表达的反式显性抑制剂，表明PG13可与这些过程所需的蛋白质特异性相互作用。尽管我们未观察到任何其他明显的表型变化，但这些转基因植物是鉴定TGA1a和PG13是否参与调控植物基因组中编码的启动子的潜在有价值工具。
