Zinc coordination is required for and regulates transcription activation by Epstein-Barr nuclear antigen 1.
Zinc coordination is required for and regulates transcription activation by Epstein-Barr nuclear antigen 1.
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DOI：
10.1371/journal.ppat.1000469
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发表时间：
2009-06
期刊：
影响因子：
6.7
通讯作者：
Aiyar A
中科院分区：
文献类型：
--
作者：
Aras S;Singh G;Johnston K;Foster T;Aiyar A
爱泼斯坦 - 巴尔核抗原1（EBNA1）对爱泼斯坦 - 巴尔病毒使幼稚B细胞永生化至关重要。在结合一组20个被称为重复序列家族的同源结合位点后，EBNA1激活对永生化必需的EBV基因的启动子。一个被称为UR1的小结构域，长度为25个氨基酸，先前已被确定为EBNA1激活转录所必需的。在这项研究中，我们阐明了UR1如何有助于EBNA1的反式激活能力。我们表明锌对EBNA1激活转录是必需的，并且UR1通过其中包含的一对关键半胱氨酸来协调锌。UR1在协调锌时二聚化，这表明EBNA1在其氨基末端包含第二个二聚化界面。UR1介导的二聚化与EBNA1协同反式激活的能力之间存在很强的相关性。破坏锌协调的EBNA1点突变体也阻止自身关联，并且不能协同激活转录。此外，我们证明UR1作为一种分子传感器，调节EBNA1响应氧化还原和氧分压（pO2）变化激活转录的能力。模拟此类环境变化的轻度氧化应激会降低淋巴母细胞系中EBNA1依赖性转录。与EBNA1依赖性转录的降低同时，观察到EBNA2和LMP1蛋白水平降低。尽管这些变化不影响LCL存活，但处理后的细胞在G0/G1期积累。我们在身体不同部位的EBV潜伏期的背景下讨论了这些发现，这些部位的pO2和氧化还原电位差异显著。
爱泼斯坦 - 巴尔病毒（EBV）感染人类B细胞并使其永生化。永生化导致从传染性单核细胞增多症到淋巴瘤等恶性肿瘤等一系列疾病。在永生化过程中，EBV表达少数调节细胞增殖和分化的病毒基因。EBV表达的基因之一，爱泼斯坦 - 巴尔核抗原1（EBNA1），激活永生化所需的其他病毒基因的表达。在本报告中，我们探索了EBNA1激活基因表达的机制。我们确定EBNA1利用微量营养素锌进行自身关联，并且自身关联对其激活基因表达是必需的。此外，我们确定诸如氧张力和氧化应激等环境条件调节EBNA1自身关联的能力，从而调节其激活基因表达的能力。已知EBV感染细胞的基因表达谱和增殖表型在人体不同的环境生态位中有所不同，例如在淋巴结和外周循环中。我们解释我们的结果并假设这些差异是由于这些微环境中不同的氧张力对EBNA1激活病毒基因表达能力的影响而产生的。我们的发现可用于开发针对EBV相关疾病的新型疗法，通过氧化应激靶向EBNA1。
Epstein-Barr Nuclear Antigen 1 (EBNA1) is essential for Epstein-Barr virus to immortalize naïve B-cells. Upon binding a cluster of 20 cognate binding-sites termed the family of repeats, EBNA1 transactivates promoters for EBV genes that are required for immortalization. A small domain, termed UR1, that is 25 amino-acids in length, has been identified previously as essential for EBNA1 to activate transcription. In this study, we have elucidated how UR1 contributes to EBNA1's ability to transactivate. We show that zinc is necessary for EBNA1 to activate transcription, and that UR1 coordinates zinc through a pair of essential cysteines contained within it. UR1 dimerizes upon coordinating zinc, indicating that EBNA1 contains a second dimerization interface in its amino-terminus. There is a strong correlation between UR1-mediated dimerization and EBNA1's ability to transactivate cooperatively. Point mutants of EBNA1 that disrupt zinc coordination also prevent self-association, and do not activate transcription cooperatively. Further, we demonstrate that UR1 acts as a molecular sensor that regulates the ability of EBNA1 to activate transcription in response to changes in redox and oxygen partial pressure (pO2). Mild oxidative stress mimicking such environmental changes decreases EBNA1-dependent transcription in a lymphoblastoid cell-line. Coincident with a reduction in EBNA1-dependent transcription, reductions are observed in EBNA2 and LMP1 protein levels. Although these changes do not affect LCL survival, treated cells accumulate in G0/G1. These findings are discussed in the context of EBV latency in body compartments that differ strikingly in their pO2 and redox potential. Epstein-Barr virus (EBV) infects human B-cells and immortalizes them. Immortalization results in diseases that range from infectious mononucleosis to malignancies such as lymphomas. During immortalization, EBV expresses a small number of viral genes that modulate cellular proliferation and differentiation. One of the genes expressed by EBV, Epstein-Barr nuclear antigen 1 (EBNA1), activates the expression of the other viral genes required for immortalization. In this report, we have explored the mechanism by which EBNA1 activates gene expression. We have determined that EBNA1 uses the micronutrient zinc to self-associate, and that self-association is necessary for it to activate gene expression. Further, we have determined that environmental conditions such as oxygen tension and oxidative stress modulate EBNA1's capacity to self-associate, and therefore to activate gene expression. The gene expression profile and proliferative phenotype of EBV-infected cells is known to vary in differing environmental niches in the human body, such as lymph nodes and in peripheral circulation. We interpret our results to postulate that these differences arise as a consequence of varying oxygen tension in these microenvironments on EBNA1's capacity to activate viral gene expression. Our findings can be exploited to devise novel therapeutics against EBV-associated diseases that target EBNA1 through oxidative stress.
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影响因子：
4.4
作者：
Chandel, NS;Trzyna, WC;Schumacker, PT
通讯作者：
Schumacker, PT
影响因子：
56.9
作者：
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作者：
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DOI：
10.1073/pnas.88.23.10875
发表时间：
1991-12-01
影响因子：
11.1
作者：
FRAPPIER, L;ODONNELL, M
通讯作者：
ODONNELL, M
影响因子：
14.9
作者：
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