Katagiri F, Lam E, Chua N H
Laboratory of Plant Molecular Biology, Rockefeller University, New York 10021.
Nature. 1989 Aug 31;340(6236):727-30. doi: 10.1038/340727a0.
The 35S promoter of the cauliflower mosaic virus (CaMV) contains a tandem repeat of the sequence TGACG in the region -83 to -63. This 21-base pair (bp) sequence, called as-1, is involved in root expression of the 35S promoter. When inserted in a promoter of a gene expressed specifically in photosynthetic tissues, as-1 confers high level expression in roots. We have described a factor, ASF-1, that binds specifically to as-1 in vitro. There is a good correlation between ASF-1 binding affinity to as-1 related sequences in vitro and the function of these sequences in vivo. These results strongly suggest that ASF-1 is responsible for the function of as-1. Here we report the isolation of tobacco complementary DNA clones encoding two TGACG-sequence-specific binding-proteins (TGA1a and TGA1b). Sequence analysis of the cDNA clones shows that both proteins contain a basic region that shows high homology to a stretch of basic amino acids in the nuclear factors CREB, GCN4, and c-Jun to a 'leucine-zipper' region. On the basis of binding specificity we propose TGA1a to be a good candidate for ASF-1.
花椰菜花叶病毒（CaMV）的35S启动子在-83至-63区域含有序列TGACG的串联重复。这个21碱基对（bp）的序列，称为as-1，参与35S启动子的根部表达。当插入在光合组织中特异性表达的基因的启动子中时，as-1赋予根部高水平表达。我们已经描述了一种因子ASF-1，它在体外特异性结合as-1。ASF-1在体外对as-1相关序列的结合亲和力与这些序列在体内的功能之间存在良好的相关性。这些结果强烈表明ASF-1负责as-1的功能。在此我们报告了编码两种TGACG序列特异性结合蛋白（TGA1a和TGA1b）的烟草互补DNA克隆的分离。cDNA克隆的序列分析表明，这两种蛋白质都含有一个碱性区域，该区域与核因子CREB、GCN4和c-Jun中的一段碱性氨基酸与一个“亮氨酸拉链”区域具有高度同源性。基于结合特异性，我们认为TGA1a是ASF-1的一个良好候选者。
