Vicente-Carbajosa J, Moose S P, Parsons R L, Schmidt R J
Department of Biology, University of California at San Diego, Mail Code 0116, La Jolla, CA 92093, USA.
Proc Natl Acad Sci U S A. 1997 Jul 8;94(14):7685-90. doi: 10.1073/pnas.94.14.7685.
The prolamin box (P-box) is a highly conserved 7-bp sequence element (5'-TGTAAAG-3') found in the promoters of many cereal seed storage protein genes. Nuclear factors from maize endosperm specifically interact with the P-box present in maize prolamin genes (zeins). The presence of the P-box in all zein gene promoters suggests that interactions between endosperm DNA binding proteins and the P-box may play an important role in the coordinate activation of zein gene expression during endosperm development. We have cloned an endosperm-specific maize cDNA, named prolamin-box binding factor (PBF), that encodes a member of the recently described Dof class of plant Cys2-Cys2 zinc-finger DNA binding proteins. When tested in gel shift assays, PBF exhibits the same sequence-specific binding to the P-box as factors present in maize endosperm nuclei. Additionally, PBF interacts in vitro with the basic leucine zipper protein Opaque2, a known transcriptional activator of zein gene expression whose target site lies 20 bp downstream of the P-box in the 22-kDa zein gene promoter. The isolation of the PBF gene provides an essential tool to further investigate the functional role of the highly conserved P-box in regulating cereal storage protein gene expression.
醇溶蛋白盒（P盒）是一种高度保守的7碱基序列元件（5'-TGTAAAG-3'），存在于许多谷物种子贮藏蛋白基因的启动子中。来自玉米胚乳的核因子能特异性地与玉米醇溶蛋白基因（玉米醇溶蛋白）中的P盒相互作用。所有玉米醇溶蛋白基因启动子中都存在P盒，这表明胚乳DNA结合蛋白与P盒之间的相互作用可能在胚乳发育过程中玉米醇溶蛋白基因表达的协同激活中起重要作用。我们克隆了一个胚乳特异性的玉米cDNA，命名为醇溶蛋白盒结合因子（PBF），它编码最近描述的植物Cys2-Cys2锌指DNA结合蛋白Dof家族的一个成员。在凝胶迁移实验中检测时，PBF与玉米胚乳细胞核中的因子一样，对P盒表现出相同的序列特异性结合。此外，PBF在体外与碱性亮氨酸拉链蛋白不透明2相互作用，不透明2是已知的玉米醇溶蛋白基因表达的转录激活因子，其靶位点位于22 kDa玉米醇溶蛋白基因启动子中P盒下游20 bp处。PBF基因的分离为进一步研究高度保守的P盒在调节谷物贮藏蛋白基因表达中的功能作用提供了一个重要工具。
