The binding interaction of HMG-1 with the TATA-binding protein/TATA complex
The binding interaction of HMG-1 with the TATA-binding protein/TATA complex
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DOI：
10.1074/jbc.m011792200
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发表时间：
2001-08-31
影响因子：
4.8
通讯作者：
Scovell, WM
中科院分区：
文献类型：
--
作者：
Das, D;Scovell, WM
高迁移率蛋白 1 (HMG-1) 已被证明可调节 RNA 聚合酶 II 的转录。在它作为转录阻遏蛋白的情况下，它与 TATA 结合蛋白 (TBP) 结合形成 HMG-1/TBP/TATA 复合物，该复合物被认为可以抑制预起始复合物的组装。通过使用电泳迁移率变动分析，我们发现 HMG-1 的酸性 C 端结构域和人 TBP 的 N 端是形成稳定的 HMG-1/TBP/TATA 复合物所必需的结构域。 HMG-1结合使TBP对TATA元件的亲和力增加20倍，这反映在TBP结合速率的显着刺激上，而对解离速率常数影响很小。为了支持 HMG-1 的结合靶标是 hTBP 的 N 末端，人 TBP 的 N 末端多肽与 HMG-1/TBP/TATA 复合物形成竞争并抑制其形成。人 TBP N 末端片段的删除用于绘制 HMG-1 结合区域的图谱。这些发现表明 HMG-1 与 hTBP 中的 Q-tract（氨基酸 55-95）的相互作用主要负责稳定复合物的形成。此外，HMG-1 和 Q-tract 特异性单克隆抗体 1C2 竞争同一位点。此外，小牛胸腺HMG-1与TBP/TATA复合物形成稳定的复合物，该复合物含有来自人类或果蝇但不含有酵母的TBP。这再次与 Q 束对于这种稳定相互作用的重要性一致，并表明这种相互作用延伸到许多物种，但不包括酵母 TBP。
High mobility protein-1 (HMG-1) has been shown to regulate transcription by RNA polymerase II. In the context that it acts as a transcriptional repressor, it binds to the TATA-binding protein (TBP) to form the HMG-1/ TBP/TATA complex, which is proposed to inhibit the assembly of the preinitiation complex. By using electrophoretic mobility shift assays, we show that the acidic C-terminal domain of HMG-1 and the N terminus of human TBP are the domains that are essential for the formation of a stable HMG-1/TBP/TATA complex. HMG-1 binding increases the affinity of TBP for the TATA element by 20-fold, which is reflected in a significant stimulation of the rate of TBP binding, with little effect on the dissociation rate constant. In support of the binding target of HMG-1 being the N terminus of hTBP, the N-terminal polypeptide of human TBP competes with and inhibits HMG-1/TBP/TATA complex formation. Deletion of segments of the N terminus of human TBP was used to map the region(s) where HMG-1 binds. These findings indicate that interaction of HMG-1 with the Q-tract (amino acids 55-95) in hTBP is primarily responsible for stable complex formation. In addition, HMG-1 and the monoclonal antibody, 1C2, specific to the Q-tract, compete for the same site. Furthermore, calf thymus HMG-1 forms a stable complex with the TBP/TATA complex that contains TBP from either human or Drosophila but not yeast. This is again consistent with the importance of the Q-tract for this stable interaction and shows that the interaction extends over many species but does not include yeast TBP.