Interaction between Basic Residues of Epstein-Barr Virus EBNA1 Protein and Cellular Chromatin Mediates Viral Plasmid Maintenance
Interaction between Basic Residues of Epstein-Barr Virus EBNA1 Protein and Cellular Chromatin Mediates Viral Plasmid Maintenance
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DOI：
10.1074/jbc.m113.491167
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发表时间：
2013-08-16
影响因子：
4.8
通讯作者：
Tsurumi, Tatsuya
中科院分区：
文献类型：
--
作者：
Kanda, Teru;Horikoshi, Naoki;Tsurumi, Tatsuya
eb病毒（EBV）基因组在潜伏感染的细胞中特别维持。病毒蛋白EBNA1是一种桥接分子，将EBV片段连接到宿主有丝分裂染色体和间期染色质上。EBNA1通过其富含甘氨酸和精氨酸残基的染色体结合域（CBDs）定位于细胞染色体（染色质）。然而，EBNA1的CBDs附着于细胞染色质的分子机制仍存在争议。突变分析表明，用丙氨酸逐步取代CBD1（氨基酸40-54）和CBD2（氨基酸328-377）区域的精氨酸残基会逐渐损害EBNA1的染色体结合活性。CBD1和-2区域内精氨酸到丙氨酸的完全取代使EBNA1在分裂细胞中稳定维持ebv衍生的oriP质粒的能力丧失。重要的是，用赖氨酸替代相同的精氨酸对EBNA1的染色体结合以及其稳定维持oriP质粒的能力的影响最小，如果有的话。此外，来自CBD1区域的富含甘氨酸-精氨酸的肽在体外与重构的核小体核心颗粒结合，富含甘氨酸-赖氨酸的肽也是如此，而富含甘氨酸-丙氨酸的肽则没有。这些结果支持了EBNA1的染色体结合是由CBDs内的碱性氨基酸和带负电荷的细胞染色质之间的静电相互作用介导的。
The Epstein-Barr virus (EBV) genome is episomally maintained in latently infected cells. The viral protein EBNA1 is a bridging molecule that tethers EBV episomes to host mitotic chromosomes as well as to interphase chromatin. EBNA1 localizes to cellular chromosomes (chromatin) via its chromosome binding domains (CBDs), which are rich in glycine and arginine residues. However, the molecular mechanism by which the CBDs of EBNA1 attach to cellular chromatin is still under debate. Mutation analyses revealed that stepwise substitution of arginine residues within the CBD1 (amino acids 40-54) and CBD2 (amino acids 328-377) regions with alanines progressively impaired chromosome binding activity of EBNA1. The complete arginine-to-alanine substitutions within the CBD1 and -2 regions abolished the ability of EBNA1 to stably maintain EBV-derived oriP plasmids in dividing cells. Importantly, replacing the same arginines with lysines had minimal effect, if any, on chromosome binding of EBNA1 as well as on its ability to stably maintain oriP plasmids. Furthermore, a glycine-arginine-rich peptide derived from the CBD1 region bound to reconstituted nucleosome core particles in vitro, as did a glycine-lysine rich peptide, whereas a glycine-alanine rich peptide did not. These results support the idea that the chromosome binding of EBNA1 is mediated by electrostatic interactions between the basic amino acids within the CBDs and negatively charged cellular chromatin.