Abaitua F, Souto R N, Browne H, Daikoku T, O'Hare P
Marie Curie Research Institute, The Chart, Oxted RH8 0TL, Surrey, UK.
Division of Virology, Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK.
J Gen Virol. 2009 Oct;90(Pt 10):2353-2363. doi: 10.1099/vir.0.012492-0. Epub 2009 Jul 8.
VP1-2, encoded by the UL36 gene of herpes simplex virus (HSV), is a large structural protein, conserved across the family Herpesviridae, that is assembled into the tegument and is essential for virus replication. Current evidence indicates that VP1-2 is a central component in the tegumentation and envelopment processes and that it also possesses important roles in capsid transport and entry. However, any detailed mechanistic understanding of VP1-2 function(s) remains limited. This study characterized the replication of HSV-1 tsB7, a temperature-sensitive mutant restricted at the non-permissive temperature due to a defect in VP1-2 function. A tsB7 virus expressing green fluorescent protein-fused VP16 protein was used to track the accumulation and location of a major tegument protein. After infection at the permissive temperature and shift to the non-permissive temperature, the production of infectious virus ceased. VP1-2 accumulated in altered cytosolic clusters, together with VP16 and other virion proteins. Furthermore, correlating with the results of immunofluorescence, electron microscopy demonstrated abnormal cytosolic capsid clustering and a block in envelopment. As VP1-2 encompasses a ubiquitin-specific protease domain, the occurrence of ubiquitin-conjugated proteins during tsB7 infection was also examined at the non-permissive temperature. A striking overaccumulation was observed of ubiquitin-specific conjugates in cytoplasmic clusters, overlapping and adjacent to the VP1-2 clusters. These results are discussed in relation to the possible functions of VP1-2 in the assembly pathway and the nature of the defect in tsB7.
由单纯疱疹病毒（HSV）的UL36基因编码的VP1-2是一种大型结构蛋白，在疱疹病毒科中保守，组装到病毒被膜中，对病毒复制至关重要。目前的证据表明，VP1-2是病毒被膜形成和包膜过程的核心成分，并且在衣壳运输和进入中也发挥重要作用。然而，对VP1-2功能的任何详细机制理解仍然有限。本研究对HSV-1 tsB7的复制进行了表征，HSV-1 tsB7是一种温度敏感突变体，由于VP1-2功能缺陷，在非允许温度下受到限制。使用表达绿色荧光蛋白融合的VP16蛋白的tsB7病毒来追踪一种主要被膜蛋白的积累和定位。在允许温度下感染并转移到非允许温度后，传染性病毒的产生停止。VP1-2与VP16和其他病毒体蛋白一起在改变的胞质簇中积累。此外，与免疫荧光结果相关，电子显微镜显示异常的胞质衣壳聚集和包膜受阻。由于VP1-2包含一个泛素特异性蛋白酶结构域，还在非允许温度下检查了tsB7感染期间泛素缀合蛋白的出现情况。在与VP1-2簇重叠和相邻的细胞质簇中观察到泛素特异性缀合物的显著过度积累。结合VP1-2在组装途径中的可能功能以及tsB7缺陷的性质对这些结果进行了讨论。
