Walter J, Dever C A, Biggin M D
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520.
Genes Dev. 1994 Jul 15;8(14):1678-92. doi: 10.1101/gad.8.14.1678.
We have used in vivo UV cross-linking to directly measure DNA binding by the homeo domain proteins even-skipped (eve) and fushi tarazu (ftz) in Drosophila embryos. Strikingly, these two proteins bind at uniformly high levels throughout the length of their genetically identified target genes and at lower, but significant, levels to genes that they are not expected to regulate. The data also suggest that these two proteins have very similar DNA-binding specificities in vivo. In contrast, a non-homeo domain transcription factor, zeste, is only detected on short DNA elements within a target promoter and not on other genes. These results are consistent with the in vitro properties of these various proteins, their respective concentrations in the nucleus, and with earlier predictions of how transcription factors bind DNA in vivo. We propose that these data favor the model that eve, ftz, and closely related homeo domain proteins act by directly regulating mostly the same target genes.
我们利用体内紫外线交联技术直接测定了果蝇胚胎中同源结构域蛋白偶数缺口（eve）和分节缺失（ftz）与DNA的结合情况。令人惊讶的是，这两种蛋白在其经遗传学鉴定的靶基因全长上均以均匀的高水平结合，而在它们预期不会调控的基因上结合水平较低，但仍有显著结合。数据还表明，这两种蛋白在体内具有非常相似的DNA结合特异性。相比之下，一种非同源结构域转录因子——小体，仅在靶启动子内的短DNA元件上被检测到，而在其他基因上未被检测到。这些结果与这些不同蛋白的体外特性、它们在细胞核中的各自浓度以及早期关于转录因子在体内如何结合DNA的预测一致。我们认为，这些数据支持这样一种模型，即eve、ftz以及密切相关的同源结构域蛋白主要通过直接调控大多数相同的靶基因来发挥作用。
