Assembling the Human IFN-β Enhanceosome in Solution
Assembling the Human IFN-β Enhanceosome in Solution
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DOI：
10.1016/j.jmb.2008.09.015
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发表时间：
2008-12-12
影响因子：
5.6
通讯作者：
Privalov, P. L.
中科院分区：
文献类型：
--
作者：
Dragan, A. I.;Carrillo, R.;Privalov, P. L.
利用荧光各向异性、微量热法和CD滴定法的组合，研究了干扰素- β增强体从其单个蛋白质组分和增强子DNA的组装。结果表明，该增强子仅在PRDII-I-PRDI位点与一个全长的拟磷IRF-3二聚体结合，而这种结合与ATF-2/c-Jun bZIP（亮氨酸拉链二聚体，具有基本DNA识别片段）异源二聚体在PRDIV位点的结合不具有协同性。因此，bZIP对的取向不是由IRF-3二聚体的存在决定的，而是由PRDIV位点的不对称性决定的。相反，结合的IRF-3二聚体与邻近PRDII位点结合的NF-kappa B （p50/p65）异源二聚体强烈相互作用。结合的NF-kappa B的取向也是由PRDII位点的不对称性决定的，与晶体结构中发现的相反。HMG-I/Y蛋白被认为是协调增强小体组装，通过将其dna结合片段（AT钩子）插入次要凹槽中，与干扰素- β增强子的PRDII位点特异性相互作用，导致NF-kappa B对该位点主要凹槽的结合亲和力显著增加。(C) 2008 Elsevier Ltd版权所有。
Assembly of interferon-beta enhanceosome from its individual protein components and of enhancer DNA has been studied in solution using a combination of fluorescence anisotropy, microcalorimetry, and CD titration. It was shown that the enhancer binds only one full-length phosphomimetic IRF-3 dimer at the PRDII-I-PRDI sites, and this binding does not exhibit cooperativity with binding of the ATF-2/c-Jun bZIP (leucine zipper dimer with basic DNA recognition segments) heterodimer at the PRDIV site. The orientation of the bZIP pair is, therefore, not determined by the presence of the IRF-3 dimer, but is predetermined by the asymmetry of the PRDIV site. In contrast, bound IRF-3 dimer interacts strongly with the NF-kappa B (p50/p65) heterodimer bound at the neighboring PRDII site. The orientation of bound NF-kappa B is also predetermined by the asymmetry of the PRDII site and is the opposite of that found in the crystal structure. The HMG-I/Y protein, proposed as orchestrating erthanceosome assembly, interacts specifically with the PRDII site of the interferon-beta enhancer by inserting its DNA-binding segments (AT hooks) into the minor groove, resulting in a significant increase in NF-kappa B binding affinity for the major groove of this site. (C) 2008 Elsevier Ltd. All rights reserved.