Ohkuma Y, Horikoshi M, Roeder R G, Desplan C
Howard Hughes Medical Institute, Rockefeller University, New York, NY 10021.
Proc Natl Acad Sci U S A. 1990 Mar;87(6):2289-93. doi: 10.1073/pnas.87.6.2289.
Engrailed (En) is a homeodomain protein that binds to a consensus sequence (NP) and plays an important role during Drosophila development. Purified En, which is produced in Escherichia coli, binds not only to this consensus sequence but also to the TATA box of the Drosophila Hsp70 promoter and of other eukaryotic promoters. Interestingly, En represses transcription of these promoters in an in vitro-reconstituted mammalian transcription system and footprint analyses show that En competes with the TATA box-binding protein transcription factor IID for binding to the TATA box. In contrast, a stable template-committed complex formed by preincubation of transcription factor IID with the promoter is not disrupted by addition of En, and in this case transcription is not repressed. These in vitro studies suggest a transcriptional repression mechanism, involving competition between En and transcription factor IID for TATA box binding, that may be involved in En-mediated repression in vivo.
Engrailed（En）是一种同源结构域蛋白，它能与共有序列（NP）结合，并在果蝇发育过程中发挥重要作用。在大肠杆菌中产生的纯化的En不仅能与该共有序列结合，还能与果蝇热休克蛋白70（Hsp70）启动子以及其他真核启动子的TATA盒结合。有趣的是，En在体外重组的哺乳动物转录系统中会抑制这些启动子的转录，足迹分析表明En与TATA盒结合蛋白转录因子IID竞争结合TATA盒。相反，转录因子IID与启动子预孵育形成的稳定的模板结合复合物不会因添加En而被破坏，在这种情况下转录也不会受到抑制。这些体外研究提示了一种转录抑制机制，即En与转录因子IID竞争结合TATA盒，这可能参与了En在体内介导的抑制作用。
