Interaction of bovine papillomavirus E2 protein with Brd4 stabilizes its association with chromatin
Interaction of bovine papillomavirus E2 protein with Brd4 stabilizes its association with chromatin
复制标题
DOI：
10.1128/jvi.79.14.8920-8932.2005
复制
发表时间：
2005-07-01
影响因子：
5.4
通讯作者：
McBride, AA
中科院分区：
文献类型：
--
作者：
McPhillips, MG;Ozato, K;McBride, AA
牛乳头瘤病毒E2蛋白通过将病毒染色体外基因组系在细胞有丝分裂染色体上来维持和分离病毒染色体外基因组。E2与细胞溴结构域蛋白Brd 4相互作用，介导病毒基因组分离到子细胞中。Brd 4结合乙酰化的组蛋白，并且已经观察到在几种细胞类型中弥漫地包被有丝分裂染色体。在这项研究中，我们表明，在有丝分裂的C127细胞，Brd 4弥漫性地包被浓缩的染色体。然而，在E2蛋白的存在下，E2和Brd 4共定位在随机分布在染色体上的点状点中。在CV-1细胞中观察到E2和Brd 4在有丝分裂染色体上共定位的类似模式，而在不存在E2蛋白的情况下仅检测到Brd 4的微弱染色体涂层。因此，病毒E2蛋白在有丝分裂细胞中重新定位和/或稳定Brd 4与染色体的结合。在间期细胞中也观察到E2和Brd 4的共定位，表明这种蛋白质-蛋白质相互作用在整个细胞周期中持续存在。E2与Brd 4的相互作用极大地稳定了Brd 4与间期染色质的缔合。在有丝分裂和间期细胞中，这种稳定需要一个转录活性的反式激活结构域，但不需要E2蛋白的DNA结合功能。因此，E2蛋白在间期和有丝分裂期间调节Brd 4的染色质缔合。这项研究表明，乳头瘤病毒基因组的分离并不简单地是由于被动搭便车的E2/基因组复合物与一个方便的细胞染色体蛋白。
The bovine papillomavirus E2 protein maintains and segregates the viral extrachromosomal genomes by tethering them to cellular mitotic chromosomes. E2 interacts with a cellular bromodomain protein, Brd4, to mediate the segregation of viral genomes into daughter cells. Brd4 binds acetylated histones and has been observed to diffusely coat mitotic chromosomes in several cell types. In this study, we show that in mitotic C127 cells, Brd4 diffusely coated the condensed chromosomes. However, in the presence of the E2 protein, E2 and Brd4 colocalized in punctate dots that were randomly distributed over the chromosomes. A similar pattern of E2 and Brd4 colocalization on mitotic chromosomes was observed in CV-1 cells, whereas only a faint chromosomal coating of Brd4 was detected in the absence of the E2 protein. Therefore, the viral E2 protein relocalizes and/or stabilizes the association of Brd4 with chromosomes in mitotic cells. The colocalization of E2 and Brd4 was also observed in interphase cells, indicating that this protein-protein interaction persists throughout the cell cycle. The interaction of E2 with Brd4 greatly stabilized the association of Brd4 with interphase chromatin. In both mitotic and interphase cells, this stabilization required a transcriptionally competent transactivation domain, but not the DNA binding function of the E2 protein. Thus, the E2 protein modulates the chromatin association of Brd4 during both interphase and mitosis. This study demonstrates that the segregation of papillomavirus genomes is not simply due to the passive hitchhiking of the E2/genome complex with a convenient cellular chromosomal protein.