Sunter G, Stenger D C, Bisaro D M
Biotechnology Center, Ohio State University, Columbus 43210.
Virology. 1994 Sep;203(2):203-10. doi: 10.1006/viro.1994.1477.
The geminivirus group is diverse and contains viruses which can be placed into three distinct subgroups on the basis of their genome organization and biological properties. However, most dicot-infecting gemiviruses possess AL1, AL2, and AL3 open reading frames. AL1 encodes the only viral protein that is absolutely required for replication, AL2 codes for a protein that transactivates the expression of virion sense promoters, and AL3 specifies a protein that enhances viral DNA replication. In the studies presented here, we examined the functional specificity of the AL1, AL2, and AL3 specifies gene products of subgroup II and subgroup III geminiviruses. Surprisingly, we found that all viruses tested were able to produce a gene product which complemented the reduced DNA replication phenotype of a tomato golden mosaic virus (TGMV) AL3 mutant. We also found that all bipartite subgroup III viruses tested produced a protein that could transactivate the virion sense promoters of a TGMV AL2 mutant, although a subgroup II virus did not. In contrast, the replication activity of AL1 protein proved to be virus specific. The data are discussed with regard to the functions of these proteins in viral replication and their practical significance for the development of crop protection strategies.
双生病毒组种类多样，根据其基因组结构和生物学特性，可将其中的病毒分为三个不同的亚组。然而，大多数感染双子叶植物的双生病毒都具有AL1、AL2和AL3开放阅读框。AL1编码病毒复制唯一绝对必需的蛋白质，AL2编码一种可反式激活病毒粒子正义启动子表达的蛋白质，AL3则指定一种能增强病毒DNA复制的蛋白质。在本文所呈现的研究中，我们检测了亚组II和亚组III双生病毒的AL1、AL2和AL3指定基因产物的功能特异性。令人惊讶的是，我们发现所有测试病毒都能够产生一种基因产物，该产物可弥补番茄金色花叶病毒（TGMV）AL3突变体DNA复制减少的表型。我们还发现，所有测试的双分体亚组III病毒都能产生一种可反式激活TGMV AL2突变体病毒粒子正义启动子的蛋白质，尽管一种亚组II病毒不能。相反，AL1蛋白的复制活性被证明具有病毒特异性。本文就这些蛋白质在病毒复制中的功能及其对作物保护策略开发的实际意义进行了讨论。
