Epstein-Barr Virus LF2 Protein Regulates Viral Replication by Altering Rta Subcellular Localization
Epstein-Barr Virus LF2 Protein Regulates Viral Replication by Altering Rta Subcellular Localization
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DOI：
10.1128/jvi.00573-10
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发表时间：
2010-10-01
影响因子：
5.4
通讯作者：
Johannsen, Eric
中科院分区：
文献类型：
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作者：
Heilmann, Andreas M. F.;Calderwood, Michael A.;Johannsen, Eric
从EB病毒（EBV）潜伏感染到裂解性复制的转换由两种病毒反式激活因子Zta和Rta控制。我们以前报道，EBV蛋白LF 2结合Rta，抑制Rta启动子激活，并阻断EBV在细胞中的复制。此外，LF 2诱导Rta的SUMO 2/3修饰。我们现在表明，这种修饰发生在Rta激活结构域（426，446，517和530）内的四个赖氨酸，Rta的sumoylation不是其抑制所必需的。共表达研究表明，在LF 2存在下，Rta被隔离到细胞核的细胞骨架。我们将LF 2结合位点定位于Rta氨基酸（aa）476至519，并表明LF 2结合对于Rta重新定位和抑制至关重要。该结合位点的核心Rta aa 500至526赋予LF 2介导的重定位和对人工转录因子GAL 4-VP 16的抑制。LF 2的突变分析提供了进一步的证据，Rta重新分布是必要的镇压。Rta定位在LF 2阳性P3 HR 1基因组复制期间发生变化，但在LF 2阴性B 95 -8基因组复制期间不发生变化。与B 95 -8细胞相比，P3 HR 1细胞中BLRF 2蛋白表达降低并延迟，这与Rta活性降低一致。相比之下，BMRF 1的表达，主要由Zta调节，没有显着不同的两个细胞系之间。我们的研究结果支持LF 2通过与Rta结合并将其重新分布到细胞核外来调节EBV复制的模型。
The switch from Epstein-Barr virus (EBV) latent infection to lytic replication is governed by two viral transactivators, Zta and Rta. We previously reported that the EBV protein LF2 binds Rta, inhibits Rta promoter activation, and blocks EBV replication in cells. In addition, LF2 induces SUMO2/3 modification of Rta. We now show that this modification occurs at four lysines within the Rta activation domain (426, 446, 517, and 530) and that sumoylation of Rta is not essential for its repression. Coexpression studies demonstrated that Rta is sequestered to the extranuclear cytoskeleton in the presence of LF2. We mapped the LF2 binding site to Rta amino acids (aa) 476 to 519 and showed that LF2 binding is critical for Rta relocalization and repression. The core of this binding site, Rta aa 500 to 526, confers LF2-mediated relocalization and repression onto the artificial transcription factor GAL4-VP16. Mutational analysis of LF2 provided further evidence that Rta redistribution is essential for repression. Rta localization changes during replication of the LF2-positive P3HR1 genome, but not during replication of the LF2-negative B95-8 genome. BLRF2 protein expression was decreased and delayed in P3HR1 cells compared with B95-8 cells, consistent with reduced Rta activity. By contrast, BMRF1 expression, regulated primarily by Zta, did not differ significantly between the two cell lines. Our results support a model in which LF2 regulates EBV replication by binding to Rta and redistributing it out of the nucleus.