White K Andrew, Nagy Peter D
Department of Biology, York University, Toronto, Ontario, Canada M3J 1P3.
Prog Nucleic Acid Res Mol Biol. 2004;78:187-226. doi: 10.1016/S0079-6603(04)78005-8.
The tombusviruses are among the most extensively studied messenger-sensed RNA plant viruses. Over the past decade, there have been numerous important advances in our understanding of the molecular biology of members in this genus. Unlike most other RNA viruses, the synthesis of tombusvirus proteins has been found to involve an atypical translational mechanism related to the uncapped and nonpolyadenylated nature of their genomes. Tombusviruses also appear to employ an unusual mechanism for transcription of the sg mRNAs that template translation of a subset of their viral proteins. In addition to these new insights into tombusvirus gene expression, there has also been significant progress made in our understanding of tombusvirus RNA replication. These studies have been facilitated greatly by small genome-derived RNA replicons, referred to as defective interfering RNAs. In addition, the development of an in vitro system to study viral RNA synthesis has allowed for dissection of some of the steps involved in the replication process. Another exciting recent advance has been the creation of yeast-based systems that support amplification of tombusvirus RNA replicons and will allow the identification of host factors involved in viral RNA synthesis. Lastly, the recombinogenic nature of tombusvirus genomes has made them ideal systems for studying RNA-RNA recombination and genetic rearrangements, both in vivo and in vitro. In this review, we compile recent information on each of the aforementioned processes-translation, transcription, replication and recombination-and discuss the significance of the results.
番茄病毒属病毒是研究最为广泛的信使感应RNA植物病毒之一。在过去十年中，我们对该属病毒成员分子生物学的理解取得了许多重要进展。与大多数其他RNA病毒不同，已发现番茄病毒属病毒蛋白的合成涉及一种与其基因组的无帽和非聚腺苷酸化性质相关的非典型翻译机制。番茄病毒属病毒似乎还采用一种不寻常的机制来转录亚基因组mRNA，这些亚基因组mRNA作为一部分病毒蛋白翻译的模板。除了对番茄病毒属病毒基因表达的这些新见解外，我们对番茄病毒属病毒RNA复制的理解也取得了重大进展。小基因组衍生的RNA复制子（称为缺陷干扰RNA）极大地促进了这些研究。此外，用于研究病毒RNA合成的体外系统的开发使得能够剖析复制过程中涉及的一些步骤。最近另一项令人兴奋的进展是创建了基于酵母的系统，该系统支持番茄病毒属病毒RNA复制子的扩增，并将有助于鉴定参与病毒RNA合成的宿主因子。最后，番茄病毒属病毒基因组的重组性质使其成为体内和体外研究RNA - RNA重组和基因重排的理想系统。在本综述中，我们汇总了关于上述每个过程——翻译、转录、复制和重组——的最新信息，并讨论了这些结果的意义。
