Division of Infectious Diseases, Department of Infectious Medicine, Kurume University School of Medicine, Fukuoka, Japan.
PLoS One. 2012;7(2):e32634. doi: 10.1371/journal.pone.0032634. Epub 2012 Feb 28.
Genetic reassortment plays a critical role in the generation of pandemic strains of influenza virus. The influenza virus RNA polymerase, composed of PB1, PB2 and PA subunits, has been suggested to influence the efficiency of genetic reassortment. However, the role of the RNA polymerase in the genetic reassortment is not well understood.
METHODOLOGY/PRINCIPAL FINDINGS: Here, we reconstituted reassortant ribonucleoprotein (RNP) complexes, and demonstrated that the PB2 subunit of A/HongKong/156/1997 (H5N1) [HK PB2] dramatically reduced the synthesis of mRNA, cRNA and vRNA when introduced into the polymerase of other influenza strains of H1N1 or H3N2. The HK PB2 had no significant effect on the assembly of the polymerase trimeric complex, or on promoter binding activity or replication initiation activity in vitro. However, the HK PB2 was found to remarkably impair the accumulation of RNP. This impaired accumulation and activity of RNP was fully restored when four amino acids at position 108, 508, 524 and 627 of the HK PB2 were mutated.
CONCLUSIONS/SIGNIFICANCE: Overall, we suggest that the PB2 subunit of influenza polymerase might play an important role for the replication of reassortant ribonucleoprotein complexes.
基因重配在流感病毒大流行株的产生中起着关键作用。流感病毒 RNA 聚合酶由 PB1、PB2 和 PA 亚基组成，有人认为它会影响基因重配的效率。然而，RNA 聚合酶在基因重配中的作用还不是很清楚。
方法/主要发现：在这里，我们重建了重配核糖核蛋白（RNP）复合物，并证明当引入其他 H1N1 或 H3N2 流感株的聚合酶时，A/HongKong/156/1997（H5N1）[HK PB2]的 PB2 亚基会显著降低 mRNA、cRNA 和 vRNA 的合成。HK PB2 对聚合酶三聚体复合物的组装、启动子结合活性或体外复制起始活性没有显著影响。然而，我们发现 HK PB2 会显著损害 RNP 的积累。当 HK PB2 的位置 108、508、524 和 627 处的四个氨基酸发生突变时，这种受损的 RNP 积累和活性可以完全恢复。
结论/意义：总的来说，我们认为流感聚合酶的 PB2 亚基可能在重配核糖核蛋白复合物的复制中发挥重要作用。
