Coiled-coil structure-mediated dimerization of template activating factor-I is critical for its chromatin remodeling activity
Coiled-coil structure-mediated dimerization of template activating factor-I is critical for its chromatin remodeling activity
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DOI：
10.1006/jmbi.1999.2898
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发表时间：
1999-07-09
影响因子：
5.6
通讯作者：
Nagata, K
中科院分区：
文献类型：
--
作者：
Miyaji-Yamaguchi, M;Okuwaki, M;Nagata, K
模板激活因子-I（TAF-I）α和TAF-I β已被鉴定为激活与病毒碱性核心蛋白（Ad core）复合的腺病毒基因组的DNA复制的宿主因子。TAF-I引起Ad核心的结构变化，从而在体外不仅刺激复制而且刺激Ad核心DNA的转录。TAF-I还通过染色质重塑激活由DNA片段和纯化的组蛋白组成的重构染色质的转录。虽然羧基末端区域，这是非常丰富的酸性氨基酸，是必不可少的TAF-I的活动，它仍然不清楚其他部分是如何参与其活动。从HeLa细胞中分离的天然TAF-I以异寡聚体或均寡聚体形式存在。在这里，我们已经证明了通过交联试验，大多数TAF-I存在的二聚体。使用缺失突变TAF-I蛋白的分析显示，TAF-I的氨基末端区域对于α和β两者都是二聚化所必需的。预测该区域形成卷曲螺旋结构。事实上，破坏这种推定结构的突变废除了二聚化能力，并降低了在Ad核心DNA复制测定中的TAF-I活性。此外，我们发现，TAF-I突变体缺乏酸性尾巴的行为在此测定中的显性阴性的方式。这些观察结果强烈表明TAF-I的二聚化对其活性是重要的。(C)北京：科学出版社.
Template activating factor-I (TAF-I)alpha and TAF-I beta have been identified as the host factors that activate DNA replication of the adenovirus genome complexed with viral basic core proteins (Ad core). TAF-I causes a structural change of the Ad core, thereby stimulating not only replication but also transcription from the Ad core DNA in vitro. TAF-I also activates transcription from the reconstituted chromatin consisting of DNA fragments and purified histones through chromatin remodeling. Although the carboxyl-terminal region, which is highly rich in acidic amino acids, is essential for the TAF-I activity, it remains unclear how other parts are involved in its activity. The native TAF-I isolated from HeLa cells exists as either hetero- or homo-oligomer. Here, we have demonstrated by cross-linking assays that most of TAF-I exists as a dimer. Analyses using deletion mutant TAF-I proteins revealed that the amino-terminal region of TAF-I common to both alpha and beta is essential for dimerization. This region is predicted to form a coiled-coil structure. Indeed, mutations disrupting this putative structure abolished the dimerization capability and reduced the TAF-I activity in the Ad core DNA replication assay. Furthermore, we found that TAF-I mutants lacking the acidic tail act in a dominant-negative manner in this assay. These observations strongly suggest that the dimerization of TAF-I is important for its activity. (C) 1999 Academic Press.