Functional Characterization of the Serine-Rich Tract of Varicella-Zoster Virus IE62.
Functional Characterization of the Serine-Rich Tract of Varicella-Zoster Virus IE62.
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水痘带状疱疹病毒 IE62 富含丝氨酸的功能特征。
DOI：
10.1128/jvi.02096-15
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发表时间：
2016
影响因子：
5.4
通讯作者：
O'Callaghan,DennisJ
中科院分区：
文献类型：
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作者：
Kim,SeongK;Shakya,AkhaleshK;Kim,Seongman;O'Callaghan,DennisJ
水痘-带状疱疹病毒（VZV）的立即早期62蛋白（IE62）是病毒的主要反式激活因子，启动病毒的生命周期，是VZV致病的关键组分。IE62具有几个反式激活所必需的结构域，包括酸性反式激活结构域（acidictrans-activation domain，ACTA）、富含丝氨酸的结构域（serine-rich tract，SRT）以及USF、TFIIB和TATA盒结合蛋白（TATA box binding protein，TBP）的结合结构域。瞬时转染试验表明，缺乏SRT的VZV IE62反式激活早期VZV ORF 61启动子的水平仅为全长IE62的16%。当用马疱疹病毒1型（EHV-1）IEP的SRT替换IE62的SRT时，其转激活活性完全恢复。单纯疱疹病毒1型（HSV-1）ICP 4缺乏一个非常弱（1.5倍）的反式激活ORF 61启动子。IE62 TAD-ICP 4嵌合蛋白具有反式激活能力（10.2倍），表明IE62 TAD-ICP 4嵌合蛋白与HSV-1 ICP 4的SRT一起反式激活病毒启动子。当SRT的丝氨酸和酸性残基被Ala、Leu和Gly取代时，修饰的IE62蛋白IE62-SRTΔSe和IE62-SRTΔAc的反式激活活性分别降低到野生型活性的46%和29%。双分子互补分析表明，IE62，EHV-1 IEP和HSV-1 VP 16的引物在人黑素瘤MeWo细胞中与Mediator 25相互作用。IE62的SRT与核仁-核糖体蛋白EAP相互作用，导致核内形成球状结构。这些结果表明SRT在VZV病毒基因的表达和复制中起重要作用。重要提示水痘带状疱疹病毒（VZV）的立即早期62蛋白（IE62）是一种主要的病毒反式激活因子，对病毒的生长至关重要。我们的数据表明，VZV IE62的富含丝氨酸的片段（SRT）在α疱疹病毒中是非常保守的，它是酸性反式激活结构域（acidictrans-activation domain，SRT）介导的反式激活所必需的。在双分子互补试验中，IE62、EHV-1 IEP和HSV-1 VP 16的TAD与细胞介体25相互作用。IE62 SRT与核仁-核糖体蛋白EAP的相互作用导致细胞核内球状结构的形成。了解IE62的E2和SRT对这种必需调节蛋白的功能的作用机制对于了解这种人类病原体的基因程序非常重要。
The immediate early 62 protein (IE62) of varicella-zoster virus (VZV), a major viraltrans-activator, initiates the virus life cycle and is a key component of pathogenesis. The IE62 possesses several domains essential fortrans-activation, including an acidictrans-activation domain (TAD), a serine-rich tract (SRT), and binding domains for USF, TFIIB, and TATA box binding protein (TBP). Transient-transfection assays showed that the VZV IE62 lacking the SRTtrans-activated the early VZV ORF61 promoter at only 16% of the level of the full-length IE62. When the SRT of IE62 was replaced with the SRT of equine herpesvirus 1 (EHV-1) IEP, itstrans-activation activity was completely restored. Herpes simplex virus 1 (HSV-1) ICP4 that lacks a TAD very weakly (1.5-fold)trans-activated the ORF61 promoter. An IE62 TAD-ICP4 chimeric protein exhibitedtrans-activation ability (10.2-fold), indicating that the IE62 TAD functions with the SRT of HSV-1 ICP4 totrans-activate viral promoters. When the serine and acidic residues of the SRT were replaced with Ala, Leu, and Gly,trans-activation activities of the modified IE62 proteins IE62-SRTΔSe and IE62-SRTΔAc were reduced to 46% and 29% of wild-type activity, respectively. Bimolecular complementation assays showed that the TAD of IE62, EHV-1 IEP, and HSV-1 VP16 interacted with Mediator 25 in human melanoma MeWo cells. The SRT of IE62 interacted with the nucleolar-ribosomal protein EAP, which resulted in the formation of globular structures within the nucleus. These results suggest that the SRT plays an important role in VZV viral gene expression and replication.IMPORTANCEThe immediate early 62 protein (IE62) of varicella-zoster virus (VZV) is a major viraltrans-activator and is essential for viral growth. Our data show that the serine-rich tract (SRT) of VZV IE62, which is well conserved within the alphaherpesviruses, is needed fortrans-activation mediated by the acidictrans-activation domain (TAD). The TADs of IE62, EHV-1 IEP, and HSV-1 VP16 interacted with cellular Mediator 25 in bimolecular complementation assays. The interaction of the IE62 SRT with nucleolar-ribosomal protein EAP resulted in the formation of globular structures within the nucleus. Understanding the mechanisms by which the TAD and SRT of IE62 contribute to the function of this essential regulatory protein is important in understanding the gene program of this human pathogen.