Honda A, Ishihama A
National Institute of Genetics, Department of Molecular Genetics, Mishima, Shizuoka, Japan.
Biol Chem. 1997 Jun;378(6):483-8.
The genome of influenza virus is composed of eight RNA segments of negative polarity. The RNA-dependent RNA polymerase is associated with each viral RNA (vRNA) segment and in virus-infected cells, involved in both transcription, i.e. vRNA-directed synthesis of viral mRNA, and two step reactions of vRNA replication, i.e. vRNA-dependent synthesis of complementary RNA (cRNA) and cRNA-dependent synthesis of vRNA. The RNA polymerase is composed of three viral proteins, PB1, PB2 and PA. PB1 is the core subunit for not only the RNA synthesis but also the assembly of PB2 and PA into this multifunctional enzyme complex. PB1 alone is able to catalyze vRNA-dependent RNA synthesis, but PB2 is required for capped RNA-dependent transcription, both together forming the transcriptase. The third P protein, PA, and an as yet unidentified host factor(s) are involved in the conversion of RNA polymerase from transcriptase to replicase. The functional map is being made for both PB1 and PB2 proteins.
流感病毒的基因组由八个负链RNA片段组成。RNA依赖的RNA聚合酶与每个病毒RNA（vRNA）片段相关联，在病毒感染的细胞中，参与转录，即vRNA指导的病毒mRNA合成，以及vRNA复制的两步反应，即vRNA依赖的互补RNA（cRNA）合成和cRNA依赖的vRNA合成。RNA聚合酶由三种病毒蛋白PB1、PB2和PA组成。PB1不仅是RNA合成的核心亚基，也是PB2和PA组装成这种多功能酶复合物的核心亚基。单独的PB1能够催化vRNA依赖的RNA合成，但加帽RNA依赖的转录需要PB2，两者共同形成转录酶。第三种P蛋白PA和一个尚未确定的宿主因子参与RNA聚合酶从转录酶到复制酶的转变。正在绘制PB1和PB2蛋白的功能图谱。
