Structural properties of the promiscuous VP16 activation domain
Structural properties of the promiscuous VP16 activation domain
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DOI：
10.1021/bi0482912
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发表时间：
2005-01-25
期刊：
影响因子：
2.9
通讯作者：
Kaptein, R
中科院分区：
文献类型：
--
作者：
Jonker, HRA;Wechselberger, RW;Kaptein, R
单纯疱疹病毒蛋白16（VP 16）含有两个强激活区，可独立或协同激活体内转录。我们已经确定了区域和残基参与的相互作用与人类转录辅激活因子正辅因子4（PC 4）和一般转录因子TFIIB。NMR和生物化学实验表明，两个VP 16激活区域是相互作用所必需的，并且在与其靶PC 4结合时经历从无规卷曲到α-螺旋的构象转变。相互作用是强烈的静电驱动和结合PC 4的存在下，其氨基末端结构域增强。我们提出的模型结合VP 16的核心结构域的PC 4和TFIIB是基于两个独立的对接方法，使用NMR化学位移的变化，在滴定实验中观察到的。该模型与定点诱变的结果是一致的，并提供了一个解释的贡献，酸性和疏水残基的转录激活VP 16。这两个本质上非结构化的激活域被吸引到他们的相互作用的合作伙伴通过静电相互作用，并采取α-螺旋构象周围的重要的疏水残基。模型显示多个不同的结合表面与各种合作伙伴的相互作用，提供了一个解释的混杂属性，协同性，和高活性的激活域。
Herpes simplex virion protein 16 (VP16) contains two strong activation regions that can independently and cooperatively activate transcription in vivo. We have identified the regions and residues involved in the interaction with the human transcriptional coactivator positive cofactor 4 (PC4) and the general transcription factor TFIIB. NMR and biochemical experiments revealed that both VP16 activation regions are required for the interaction and undergo a conformational transition from random coil to alpha-helix upon binding to its target PC4. The interaction is strongly electrostatically driven and the binding to PC4 is enhanced by the presence of its amino-terminal domain. We propose models for binding of VP16 to the core domains of PC4 and TFIIB that are based on two independent docking approaches using NMR chemical shift changes observed in titration experiments. The models are consistent with results from site-directed mutagenesis and provide an explanation for the contribution of both acidic and hydrophobic residues for transcriptional activation by VP16. Both intrinsically unstructured activation domains are attracted to their interaction partner by electrostatic interactions, and adopt an alpha-helical conformation around the important hydrophobic residues. The models showed multiple distinct binding surfaces upon interaction with various partners, providing an explanation for the promiscuous properties, cooperativity, and the high activity of this activation domain.