Blümel J, Gräper S, Matz B
Institut für Medizinische Mikrobiologie und Immunologie, Universität Bonn, Sigmund-Freud-Strasse 25, Bonn, D-53127, Germany.
Virology. 2000 Oct 25;276(2):445-54. doi: 10.1006/viro.2000.0574.
Replicating herpes simplex virus type 1 (HSV-1) DNA is known to form large branched structures. The aim of this study was to define whether HSV-1-specific DNA elements in cis play a critical role in formation of this structure. We did this by investigating the structure of heterologous simian virus 40 (SV40) DNA, which is replicated in HSV-infected cells by SV40 large T-antigen and defined HSV-encoded replication factors (e.g., DNA polymerase, single-stranded DNA-binding protein, and helicase-primase). During this process, extrachromosomal concatemeric DNA replication products are formed, indicating a herpesvirus-specific replication mode. In this study, we found that the replicating SV40 DNA consisted of a complex branched structure indistinguishable from that of replicating HSV DNA. Thus, no HSV-specific DNA element is necessary in cis for the formation of the large branched structure during HSV DNA replication. The trans-acting HSV DNA replication proteins seem to be sufficient to generate these complex structures. Moreover, replicating SV40 DNA showed a high frequency of homologous recombination events, which is typical for HSV DNA replication. However, in contrast to HSV origin-bearing amplicon plasmids, SV40 plasmids bearing the HSV cleavage-packaging signal were not efficiently processed to linear 150-kb DNA packaged into HSV capsids. This indicates that initiation of DNA synthesis on HSV-ori determines some, yet undefined, property of replicating HSV DNA, which is crucial for regular processing of the replication intermediates to daughter genomes.
已知复制单纯疱疹病毒1型（HSV-1）DNA会形成大型分支结构。本研究的目的是确定顺式作用的HSV-1特异性DNA元件在该结构形成中是否起关键作用。我们通过研究异源猴病毒40（SV40）DNA的结构来进行此项研究，SV40 DNA在HSV感染的细胞中由SV40大T抗原进行复制，并确定了HSV编码的复制因子（如DNA聚合酶、单链DNA结合蛋白和解旋酶-引物酶）。在此过程中，会形成染色体外串联DNA复制产物，这表明了一种疱疹病毒特异性的复制模式。在本研究中，我们发现复制的SV40 DNA由一种复杂的分支结构组成，与复制的HSV DNA的结构无法区分。因此，在HSV DNA复制过程中，顺式作用的情况下不需要HSV特异性DNA元件来形成大型分支结构。反式作用的HSV DNA复制蛋白似乎足以产生这些复杂结构。此外，复制的SV40 DNA显示出高频的同源重组事件，这是HSV DNA复制的典型特征。然而，与携带HSV起始位点的扩增子质粒不同，携带HSV切割包装信号的SV40质粒不能有效地加工成包装到HSV衣壳中的150 kb线性DNA。这表明在HSV-ori上启动DNA合成决定了复制的HSV DNA的一些尚未明确的特性，这对于将复制中间体正常加工成子代基因组至关重要。
