Corepressor required for adenovirus E1B 55,000-molecular-weight protein repression of basal transcription.
Corepressor required for adenovirus E1B 55,000-molecular-weight protein repression of basal transcription.
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腺病毒 E1B 55,000 分子量蛋白抑制基础转录所需的辅阻遏物。
DOI：
10.1128/mcb.19.5.3403
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发表时间：
1999
影响因子：
5.3
通讯作者：
Berk,AJ
中科院分区：
文献类型：
--
作者：
Martin,ME;Berk,AJ
腺病毒E1 B 55，000分子量蛋白（55 K）与宿主细胞p53结合，使其稳定，大大增加其对其同源DNA结合位点的亲和力，并将其从受调节的激活剂转化为组成性阻遏物。在这里，我们分析了p53-E1 B 55 K复合物的抑制机制。E1 B 55 K抑制需要55 K通过直接结合DNA结合的p53而与启动子相连。转录从组装，p53激活preinitiation复合物没有抑制随后加入E1 B 55 K，这表明无论是网站的55 K与p53或55 K在preinitiation复合物的目标相互作用被阻断。在缺乏TFIIA和用重组TATA结合蛋白代替TFIID的反应中观察到特异性E1 B 55 K抑制，在此条件下p53不激活转录。因此，E1 B 55 K并不简单地抑制p53特异性激活机制，而是阻断基础转录。因此，E1 B 55 K可以抑制任何具有相关p53结合位点的启动子的转录，无论与该启动子相关的其他激活剂是什么。E1 B 55 K没有抑制基础转录与重组和高度纯化的一般转录因子和RNA聚合酶II的反应，而是需要一个辅阻遏物，与聚合酶copurifies。
Adenovirus E1B 55,000-molecular-weight protein (55K) binds to host cell p53, stabilizing it, greatly increasing its affinity for its cognate DNA-binding site, and converting it from a regulated activator to a constitutive repressor. Here we analyzed the mechanism of repression by the p53-E1B 55K complex. E1B 55K repression requires that 55K be tethered to the promoter by binding directly to DNA-bound p53. Transcription from an assembled, p53-activated preinitiation complex was not repressed by the subsequent addition of E1B 55K, suggesting that either sites of 55K interaction with p53 or targets of 55K in the preinitiation complex are blocked. Specific E1B 55K repression was observed in reactions lacking TFIIA and with recombinant TATA-binding protein in place of TFIID, conditions under which p53 does not activate transcription. Thus, E1B 55K does not simply inhibit a p53-specific activation mechanism but rather blocks basal transcription. As a consequence, E1B 55K may repress transcription from any promoter with an associated p53-binding site, no matter what other activators associate with the promoter. E1B 55K did not repress basal transcription in reactions with recombinant and highly purified general transcription factors and RNA polymerase II but rather required a corepressor that copurifies with the polymerase.