Zhao Y, Holden V R, Harty R N, O'Callaghan D J
Department of Microbiology and Immunology, Louisiana State University Medical Center, Shreveport 71130-3932.
J Virol. 1992 Sep;66(9):5363-72. doi: 10.1128/JVI.66.9.5363-5372.1992.
The DNA sequence of 3,240 nucleotides of the XbaI G fragment located in the unique long (UL) region of the equine herpesvirus 1 genome revealed two major open reading frames (ORFs) designated UL3 and UL4. The UL3 ORF of 470 amino acids (aa) maps at nucleotides (nt) 4450 to 3038 from the long terminus, and its predicted 51.4-kDa protein product exhibits significant homology to the ICP27 alpha regulatory protein of herpes simplex virus type 1 (HSV-1; 32% identity) and to the ORF4 protein of varicella-zoster virus (13% identity). Interestingly, a zinc finger motif is conserved in the C-terminal domains of both ICP27 of HSV-1 (aa 483 to 508) and UL3 of equine herpesvirus 1 (aa 441 to 466). The UL4 ORF of 343 aa maps at nt 5618 to 4587 and could encode a protein of 38.1 kDa which exhibits significant homology to the UL53 protein (cell fusion protein or glycoprotein K) of HSV-1 (26% identity) and to the ORF5 protein of varicella-zoster virus (33% identity). Analyses of the UL4 amino acid sequence revealed domains characteristic of a membrane-bound glycoprotein and included potential signature sequences for (i) a signal sequence, (ii) two N-linked glycosylation sites, and (iii) four transmembrane domains. Nucleotide sequence analyses also revealed potential TATA boxes located upstream of the UL3 and UL4 ORFs. However, only a single polyadenylation signal (nt 2988 to 2983) was detected downstream of the UL3 ORF. Northern (RNA) blot hybridization and S1 nuclease analyses were used to map and characterize the UL3 and UL4 mRNAs. Metabolic inhibitors were used to identify the kinetic class of these two genes. The data revealed that UL3 is an early gene that encodes a 1.6-kb mRNA, while UL4 is a late gene encoding a 3.8-kb mRNA that overlaps the UL3 transcript. Both transcripts were shown by S1 nuclease analyses to initiate 24 to 26 nt downstream of their respective TATA boxes and to have a common transcription termination signal as a pair of 3'-coterminal mRNAs.
位于马疱疹病毒1型基因组独特长（UL）区域的XbaI G片段的3240个核苷酸的DNA序列揭示了两个主要的开放阅读框（ORF），分别命名为UL3和UL4。UL3开放阅读框由470个氨基酸（aa）组成，位于从长末端起的核苷酸（nt）4450至3038处，其预测的51.4 kDa蛋白质产物与单纯疱疹病毒1型（HSV - 1）的ICP27α调节蛋白具有显著同源性（同一性为32%），与水痘 - 带状疱疹病毒的ORF4蛋白具有显著同源性（同一性为13%）。有趣的是，锌指基序在HSV - 1的ICP27（氨基酸483至508）和马疱疹病毒1型的UL3（氨基酸441至466）的C末端结构域中是保守的。UL4开放阅读框由343个氨基酸组成，位于nt 5618至4587处，可编码一种38.1 kDa的蛋白质，该蛋白质与HSV - 1的UL53蛋白（细胞融合蛋白或糖蛋白K）具有显著同源性（同一性为26%），与水痘 - 带状疱疹病毒的ORF5蛋白具有显著同源性（同一性为33%）。对UL4氨基酸序列的分析揭示了膜结合糖蛋白的特征结构域，包括（i）信号序列、（ii）两个N - 连接糖基化位点和（iii）四个跨膜结构域的潜在特征序列。核苷酸序列分析还揭示了位于UL3和UL4开放阅读框上游的潜在TATA框。然而，仅在UL3开放阅读框下游检测到一个单一的聚腺苷酸化信号（nt 2988至2983）。Northern（RNA）印迹杂交和S1核酸酶分析用于定位和表征UL3和UL4 mRNA。使用代谢抑制剂来鉴定这两个基因的动力学类别。数据显示，UL3是一个早期基因，编码一个1.6 kb的mRNA，而UL4是一个晚期基因，编码一个3.8 kb的mRNA，该mRNA与UL3转录本重叠。S1核酸酶分析表明，这两种转录本均在各自TATA框下游24至26 nt处起始，并且作为一对3' - 共末端mRNA具有共同的转录终止信号。
