Lan Y, Fujioka M, Polsgrove R, Miskiewicz P, Morrissey D, Goto T, Weir M
Department of Biology, Wesleyan University, Middletown, Connecticut 06459, USA.
Dev Genet. 1998;23(1):45-55. doi: 10.1002/(SICI)1520-6408(1998)23:1<45::AID-DVG5>3.0.CO;2-6.
The Drosophila Paired (Prd) transcription factor has homeodomain (HD) and paired domain (PD) DNA-binding activities required for in vivo function. Correspondingly, Prd activation of late even-skipped (eve) expression occurs through a conserved target sequence (PTE) with HD and PD half sites, both of which are required for activation. To investigate the relationship between the HD and PD, and their roles in conferring specificity to Prd function, we tested altered versions of the Prd protein and of the PTE target site using in vivo assays in embryos. We found that function through PTE was constrained by the targeting specifications of both the HD and PD as well as the spatial relationship between these two domains. PTE function was also constrained by the spacing between the target half sites for the PD and HD, although surprisingly, late eve activation was retained when PTE was replaced by in vitro optimized binding sites for either the PD alone or for an HD dimer. In contrast to late eve regulation, other Prd targets tolerated more changes in the Prd protein, suggesting that their target sequences may be qualitatively different from PTE.
果蝇配对（Prd）转录因子具有体内功能所需的同源结构域（HD）和配对结构域（PD）DNA结合活性。相应地，Prd对晚期偶数跳动（eve）表达的激活通过具有HD和PD半位点的保守靶序列（PTE）发生，这两个位点都是激活所必需的。为了研究HD和PD之间的关系，以及它们在赋予Prd功能特异性方面的作用，我们在胚胎中使用体内试验测试了Prd蛋白和PTE靶位点的改变版本。我们发现，通过PTE的功能受到HD和PD的靶向规范以及这两个结构域之间空间关系的限制。PTE功能也受到PD和HD靶半位点之间间距的限制，不过令人惊讶的是，当PTE被单独针对PD或HD二聚体的体外优化结合位点取代时，晚期eve激活得以保留。与晚期eve调控相反，其他Prd靶标对Prd蛋白的变化耐受性更强，这表明它们的靶序列可能在性质上与PTE不同。
