Paterson T, Preston V G, Everett R D
MRC Virology Unit, Institute of Virology, Glasgow, U.K.
J Gen Virol. 1990 Apr;71 ( Pt 4):851-61. doi: 10.1099/0022-1317-71-4-851.
Vmw175, the product of herpes simplex virus type 1 immediate early (IE) gene 3, is essential for viral replication. It is required for the activation of transcription from both early and late gene promoters and also for the repression of IE gene expression. Vmw175 is able to bind specifically to certain DNA sequences, some of which (including that at the cap site of IE gene 3) contain the consensus sequence ATCGTC. The presence of this sequence at the cap site has been correlated with the ability of Vmw175 to autoregulate its own promoter. This report describes the characterization of five viruses with temperature-sensitive (ts) lesions in Vmw175. Four of these mutants express Vmw175 which is ts in its ability to bind to DNA in vitro and to autoregulate IE-3 gene expression in the infected cell. Although Vmw175 produced by the remaining mutant, ts1225, fails to autoregulate IE-3 expression at the non-permissive temperature (NPT) its DNA-binding properties are indistinguishable from those of the wild-type protein. This suggests that the ability of Vmw175 to bind to the IE-3 cap site (as measured in vitro) is insufficient for autoregulation (in vivo). All five newly characterized ts mutants are partially permissive for early gene transcription at the NPT, although Vmw175 expressed by four of them is unable to bind to the IE-3 cap site sequence at elevated temperatures. This suggests that binding to one class of recognition sequences by Vmw175, as measured in vitro, is not absolutely required for the activation of early gene promoters during virus infection. The lesions in these five ts mutants lie in the carboxy-terminal third of the polypeptide; three of the mutations (those in ts1219, ts1221 and ts1225) were identified by DNA sequence analysis and were found to affect amino acid residues that are conserved in the homologous proteins from varicella-zoster virus and pseudorabies virus.
Vmw175是单纯疱疹病毒1型立即早期（IE）基因3的产物，对病毒复制至关重要。它是早期和晚期基因启动子转录激活以及IE基因表达抑制所必需的。Vmw175能够特异性结合某些DNA序列，其中一些序列（包括IE基因3帽位点处的序列）含有共有序列ATCGTC。该序列在帽位点的存在与Vmw175自身调节其启动子的能力相关。本报告描述了在Vmw175中具有温度敏感（ts）损伤的五种病毒的特征。这些突变体中的四个表达的Vmw175在体外结合DNA以及在感染细胞中自身调节IE - 3基因表达的能力方面是温度敏感的。尽管由其余突变体ts1225产生的Vmw175在非允许温度（NPT）下不能自身调节IE - 3表达，但其DNA结合特性与野生型蛋白无异。这表明Vmw175结合IE - 3帽位点的能力（如体外测量）不足以进行自身调节（体内）。所有五个新鉴定的ts突变体在NPT时对早期基因转录部分允许，尽管其中四个表达的Vmw175在高温下不能结合IE - 3帽位点序列。这表明在病毒感染期间，如体外测量的那样，Vmw175与一类识别序列的结合并非早期基因启动子激活绝对必需的。这五个ts突变体中的损伤位于多肽的羧基末端三分之一处；通过DNA序列分析鉴定了三个突变（ts1219、ts1221和ts1225中的突变），并发现它们影响水痘 - 带状疱疹病毒和伪狂犬病病毒同源蛋白中保守的氨基酸残基。
