Murine gammaherpesvirus 68 ORF52 encodes a tegument protein required for virion morphogenesis in the cytoplasm
Murine gammaherpesvirus 68 ORF52 encodes a tegument protein required for virion morphogenesis in the cytoplasm
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DOI：
10.1128/jvi.01233-06
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发表时间：
2007-09-01
影响因子：
5.4
通讯作者：
Sun, Ren
中科院分区：
文献类型：
--
作者：
Bortz, Eric;Wang, Lili;Sun, Ren
疱疹病毒科γ亚科病毒的被膜是覆盖在核衣壳上的一种半有序的蛋白质基质，位于病毒粒子包膜之下。小鼠γ疱疹病毒68 （MHV-68）是研究γ疱疹病毒粒子结构、组装和组成的稳健模型，因为MHV-68能有效地完成裂解期并感染培养细胞。我们发现MHV-68 ORF52编码丰富的被膜蛋白，在伽玛疱疹病毒中保守。洗涤剂敏感性实验表明，MIIV-68 ORF52蛋白与病毒粒子核衣壳的结合比ORF45被膜蛋白更紧密，但可以与保留ORF65小衣壳蛋白的颗粒分离。ORF52被增强的绿色荧光蛋白或FLAG表位标记，定位在细胞质上。重组MHV-68细菌人工染色体突变体将无义突变整合到ORF52中，表现出病毒DNA复制、后期裂解基因表达以及衣壳组装和包装水平接近野生型。然而，MHV-68 ORF52-null病毒缺乏感染性病毒粒子的组装和释放。相反，ORF52-null突变体产生的部分被膜衣壳在细胞质中积累，含有保守的衣壳蛋白，ORF64和ORF67被膜蛋白，但几乎没有OPF45被膜蛋白。因此，ORF52对于传染性MHV-68颗粒在细胞质中的形成和输出至关重要，这表明在γ疱疹病毒病毒粒子形态发生中具有重要的保守功能。
The tegument, a semiordered matrix of proteins overlying the nucleocapsid and underlying the virion envelope, in viruses in the gamma subfamily of Herpesviridae is poorly understood. Murine gammaherpesvirus 68 MHV-68, is a robust model for studying gammaherpesvirus virion structure, assembly, and composition, as MHV-68 efficiently completes the lytic phase and productively infects cultured cells. We have found that MHV-68 ORF52 encodes an abundant tegument protein conserved among gammaherpesviruses. Detergent sensitivity experiments revealed that the MIIV-68 ORF52 protein is more tightly bound to the virion nucleocapsid than the ORF45 tegument protein but could be dissociated from particles that retained the ORF65 small capsomer protein. ORF52, tagged with enhanced green fluorescent protein or FLAG epitope, localized to the cytoplasm. A recombinant MHV-68 bacterial artificial chromosome mutant with a nonsense mutation incorporated into ORF52 exhibited viral DNA replication, expression of late lytic genes, and capsid assembly and packaging at levels near those of the wild type. However, the MHV-68 ORF52-null virus was deficient in the assembly and release of infectious virion particles. Instead, partially tegumented capsids produced by the ORF52-null mutant accumulated in the cytoplasm, containing conserved capsid proteins, the ORF64 and ORF67 tegument proteins, but virtually no OPF45 tegument protein. Thus, ORF52 is essential for the tegumentation and egress of infectious MHV-68 particles in the cytoplasm, suggesting an important conserved function in gammaherpesvirus virion morphogenesis.