Focal distribution of baculovirus IE1 triggered by its binding to the hr DNA elements
Focal distribution of baculovirus IE1 triggered by its binding to the hr DNA elements
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DOI：
10.1128/jvi.79.1.39-46.2005
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发表时间：
2005-01-01
影响因子：
5.4
通讯作者：
Matsumoto, S
中科院分区：
文献类型：
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作者：
Nagamine, T;Kawasaki, Y;Matsumoto, S
在家蚕杆状病毒核型多角体病毒（BmNPV）感染的BmN细胞中，IE 1是一种主要的转录激活因子，定位于病毒DNA复制的位点。IE 1最初显示局灶性分布在BmNPV感染的细胞之前，DNA合成，而通过与IE 1基因转染表达的蛋白质分布在整个核质，而不是本地化到离散的亚核结构。为了鉴定IE 1的病灶形成诱导物，我们用IE 1-GFP构建体进行了转染实验，发现与带有同源区（hr）序列的基因组DNA片段共转染导致IE 1-绿色荧光蛋白（GFP）病灶的形成。用仅含有hr 3序列和IE 1-GFP基因的单个质粒转染昆虫细胞足以形成IE 1-GFP病灶。这些结果表明，hr元素是IE 1的焦点分布的主要决定因素。对一系列hr 3缺失突变体的分析表明，单拷贝的直接重复序列可以诱导IE 1灶的形成。IE 1-GFP的hr-结合结构域内的靶向诱变导致hr依赖性IE 1定位的损害，表明IE 1与hr元件的结合对于IE 1焦点形成的开始是必不可少的。在非BmNPV易感细胞中观察到BmNPV IE 1病灶表明，hr依赖性IE 1病灶的形成不需要物种特异性因素。
In BmN cells infected with the baculovirus Bombyx mori nucleopolyhedrovirus (BmNPV), IE1, a principal transcriptional activator, localizes to sites of viral DNA replication. IE1 initially displays focal distribution in BmNPV-infected cells prior to DNA synthesis, whereas the protein expressed by transfection with the ie1 gene is distributed throughout the nucleoplasm instead of localized to discrete subnuclear structures. To identify the inducer of focus formation for IE1, we conducted transfection experiments with an IE1-GFP construct and found that cotransfection with genomic DNA fragments bearing the homologous region (hr) sequences caused the formation of IE1-green fluorescent protein (GFP) foci. The transfection of insect cells with a single plasmid containing exclusively the hr3 sequence and the IE1-GFP gene was sufficient to form IE1-GFP foci. These results suggest that hr elements are a primary determinant of the focal distribution of IE1. An analysis of a series of hr3 deletion mutants showed that a single copy of the direct repeat could induce the formation of IE1 foci. Targeted mutagenesis within the hr-binding domain of IE1-GFP caused impairment of the hr-dependent IE1 localization, suggesting that binding of IE1 to the hr elements is essential for the onset of IE1 focus formation. The observation of BmNPV IE1 foci in non-BmNPV-susceptible cells suggests that no species-specific factors are required for hr-dependent IE1 focus formation.