Intra- and intermolecular cooperative binding of high-mobility-group protein I(Y) to the beta-interferon promoter.
Intra- and intermolecular cooperative binding of high-mobility-group protein I(Y) to the beta-interferon promoter.
复制标题
高迁移率基团蛋白 I(Y) 与 β-干扰素启动子的分子内和分子间协同结合。
DOI：
10.1128/mcb.17.7.3649
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发表时间：
1997
影响因子：
5.3
通讯作者：
Thanos,D
中科院分区：
文献类型：
--
作者：
Yie,J;Liang,S;Merika,M;Thanos,D
哺乳动物高迁移率族蛋白I（Y）[HMG I（Y）]虽然不是典型的转录激活因子，但对许多真核基因的表达是必需的。HMG I（Y）似乎通过蛋白质-DNA和蛋白质-蛋白质相互作用募集和稳定转录激活因子复合物。这种蛋白质通过三个短的基本重复序列与DNA的小沟结合，优先选择排列在DNA螺旋同一面的腺嘌呤和胸腺嘧啶束。然而，这三种基本重复序列共同识别HMG I（Y）结合位点的模式仍不清楚。在这里，使用HMG I（Y）的缺失突变体、DNA酶I足迹、甲基化干扰和体内转录测定，我们表征了HMG I（Y）与模型β-干扰素增强子的结合。我们发现两个HMG I（Y）分子以高度合作的方式与增强子结合，每个分子使用一对不同的基本重复序列来识别结合位点的串联AT富集区。我们还表征了每个基本重复序列的功能，表明只有中心重复序列占特异性DNA结合，并且与相邻AT丰富区域结合的第二重复序列的存在导致结合中的分子内协同性。令人惊讶的是，HMG I（Y）的羧基末端酸性尾对于全长蛋白的特异性结合也很重要。我们的研究结果提出了一个详细的检查HMG I（Y）结合在一个重要的生物学背景下，它不仅可以扩展到HMG I（Y）结合在其他系统中，但也有许多其他蛋白质的结合模式含有同源的基本重复，这已经从细菌到人类的保守。
The mammalian high-mobility-group protein I(Y) [HMG I(Y)], while not a typical transcriptional activator, is required for the expression of many eukaryotic genes. HMG I(Y) appears to recruit and stabilize complexes of transcriptional activators through protein-DNA and protein-protein interactions. The protein binds to the minor groove of DNA via three short basic repeats, preferring tracts of adenines and thymines arranged on the same face of the DNA helix. However, the mode by which these three basic repeats function together to recognize HMG I(Y) binding sites has remained unclear. Here, using deletion mutants of HMG I(Y), DNase I footprinting, methylation interference, and in vivo transcriptional assays, we have characterized the binding of HMG I(Y) to the model beta-interferon enhancer. We show that two molecules of HMG I(Y) bind to the enhancer in a highly cooperative fashion, each molecule using a distinct pair of basic repeats to recognize the tandem AT-rich regions of the binding sites. We have also characterized the function of each basic repeat, showing that only the central repeat accounts for specific DNA binding and that the presence of a second repeat bound to an adjacent AT-rich region results in intramolecular cooperativity in binding. Surprisingly, the carboxyl-terminal acidic tail of HMG I(Y) is also important for specific binding in the context of the full-length protein. Our results present a detailed examination of HMG I(Y) binding in an important biological context, which can be extended not only to HMG I(Y) binding in other systems but also to the binding mode of many other proteins containing homologous basic repeats, which have been conserved from bacteria to humans.