Gronenborn Bruno
Institut des Sciences Végétales, CNRS, 91198, Gif sur Yvette, France.
Vet Microbiol. 2004 Feb 4;98(2):103-9. doi: 10.1016/j.vetmic.2003.10.015.
Nanoviruses, single-stranded DNA (ssDNA) plant viruses with a multipartite genome, share similarities with members of the Circoviridae family that infect mammals or birds as well as with the Geminiviridae, the only other plant virus family with circular ssDNA genomes. Although the virions of the latter are unique and different from that of the circoviruses, the mode of replication of viruses with monopartite or multipartite circular ssDNA genomes is strikingly similar. They multiply by rolling circle replication using virus-encoded multifunctional replication initiator proteins (Rep proteins) that catalyse initiation of ssDNA replication and resolution of replicative ssDNA into circular single-stranded virion DNA. All these ssDNA viruses exploit host polymerases for DNA synthesis and code for proteins that modulate the host's cell cycle favourably for virus multiplication. Recent three-dimensional structure analyses of a geminivirus and a parvovirus Rep protein have revealed an intriguing similarity between the catalytic domains of their respective Rep proteins. Furthermore, these structural data revealed that ssDNA virus replication initiator proteins might represent evolutionary intermediates between certain RNA-binding proteins and some multifunctional origin-binding proteins of papovaviruses.
纳米病毒是具有多分体基因组的单链DNA（ssDNA）植物病毒，与感染哺乳动物或鸟类的圆环病毒科成员以及双生病毒科（唯一具有环状ssDNA基因组的另一植物病毒科）的成员具有相似性。尽管双生病毒科的病毒粒子独特且与圆环病毒不同，但具有单分体或多分体环状ssDNA基因组的病毒的复制模式却惊人地相似。它们通过滚环复制进行增殖，利用病毒编码的多功能复制起始蛋白（Rep蛋白），这些蛋白催化ssDNA复制的起始，并将复制性ssDNA切割成环状单链病毒粒子DNA。所有这些ssDNA病毒都利用宿主聚合酶进行DNA合成，并编码有利于病毒增殖的调节宿主细胞周期的蛋白质。最近对一种双生病毒和一种细小病毒Rep蛋白的三维结构分析揭示了它们各自Rep蛋白催化结构域之间有趣的相似性。此外，这些结构数据表明，ssDNA病毒复制起始蛋白可能代表某些RNA结合蛋白与乳头多瘤空泡病毒的一些多功能起始结合蛋白之间的进化中间体。
