Condit R C, Xiang Y, Lewis J I
Department of Molecular Genetics and Microbiology, University of Florida, Gainesville 32610, USA.
Virology. 1996 Jun 1;220(1):10-9. doi: 10.1006/viro.1996.0280.
This report provides genetic evidence that two vaccinia virus genes, A18R and G2R, both of which affect the fidelity of viral transcription in vivo, interact with each other or act on a common biochemical pathway. Previous experiments with the antipoxviral drug isatin-beta-thiosemicarbazone suggest that lethal mutation of gene G2R would compensate for mutations in gene A18R. We therefore tested the hypothesis that gene G2R is an extragenic suppressor of A18R mutations. First, we constructed a recombinant which contains both a G2R deletion mutation and an A18R temperature-sensitive mutation and found that this recombinant was viable. Second, we isolated both cold-sensitive and temperature-insensitive phenotypic revertants of A18R temperature-sensitive mutants and found in both cases that the revertants contained G2R mutations. In the case of the cold-sensitive revertants, we were able to prove that the cold-sensitive phenotype mapped to the G2R gene. Combined with the biochemical data on A18R and G2R, these results imply that the A18R and G2R genes interact with each other either directly or indirectly in a fashion which affects the fidelity of intermediate and late viral transcription.
本报告提供了遗传学证据，表明两种痘苗病毒基因A18R和G2R在体内均影响病毒转录的保真度，它们彼此相互作用或作用于共同的生化途径。先前使用抗痘病毒药物异烟肼-β-硫代半卡巴腙的实验表明，基因G2R的致死性突变可补偿基因A18R中的突变。因此，我们检验了基因G2R是A18R突变的基因外抑制因子这一假设。首先，我们构建了一个同时包含G2R缺失突变和A18R温度敏感突变的重组体，发现该重组体是有活力的。其次，我们分离了A18R温度敏感突变体的冷敏感和温度不敏感表型回复突变体，并且在这两种情况下都发现回复突变体含有G2R突变。对于冷敏感回复突变体，我们能够证明冷敏感表型定位于G2R基因。结合关于A18R和G2R的生化数据，这些结果表明A18R和G2R基因以影响病毒中期和晚期转录保真度的方式直接或间接相互作用。
