Wang Z, Ueda T, Messing J
Waksman Institute, Rutgers, The State University of New Jersey, Piscataway, NJ 08855-0759, USA.
Gene. 1998 Nov 26;223(1-2):321-32. doi: 10.1016/s0378-1119(98)00244-3.
A maize prolamin box (P-box)-binding factor (PBF-1) has been purified and characterized from immature endosperm tissue. PBF-1 has a molecular weight of 38kDa. It is detected only in endosperm, but not in root or leaf tissues, consistent with its tissue-specific function. Site-directed mutagenesis experiments reveal that both the P-box and its flanking sequences are important for PBF-1 DNA binding. Developmental studies show that PBF-1 accumulates in the endosperm from 8 to at least 30days after pollination (DAP). From 16 to 24DAP, however, multiple shifted bands of protein(s)-DNA complexes can be observed, which correlate with an increase in zein gene expression. PBF-1 can also bind to the P-box from '22-kDa' and '19-kDa' zein promoters, but at a lower affinity than to the '27-kDa' zein promoter. The effects of protein dephosphorylation and zinc ion chelators on PBF-1 DNA binding activity are also shown. A model is proposed where PBF-1 serves as a 'recruiter' of class-specific transcription factors like Opaque2 (O2).
已从未成熟胚乳组织中纯化并鉴定出一种玉米醇溶蛋白盒（P盒）结合因子（PBF-1）。PBF-1的分子量为38kDa。仅在胚乳中检测到它，而在根或叶组织中未检测到，这与其组织特异性功能一致。定点诱变实验表明，P盒及其侧翼序列对PBF-1与DNA的结合都很重要。发育研究表明，PBF-1在授粉后8天至至少30天（DAP）期间在胚乳中积累。然而，在授粉后16至24天，可观察到蛋白质-DNA复合物的多条迁移条带，这与醇溶蛋白基因表达的增加相关。PBF-1也可以与“22kDa”和“19kDa”醇溶蛋白启动子的P盒结合，但亲和力低于与“27kDa”醇溶蛋白启动子的结合。还展示了蛋白质去磷酸化和锌离子螯合剂对PBF-1与DNA结合活性的影响。提出了一个模型，其中PBF-1作为不透明2（O2）等类特异性转录因子的“招募者”。
