de Graaff M, Houwing C J, Lukács N, Jaspars E M
Institute of Molecular Plant Sciences, Leiden University, The Netherlands.
FEBS Lett. 1995 Sep 11;371(3):219-22. doi: 10.1016/0014-5793(95)00875-a.
An RNA-dependent RNA polymerase (RdRp) purified from alfalfa mosaic virus-infected tobacco is capable of synthesizing in vitro full-size RNAs of minus and plus polarities. However, the enzyme is not able to perform a complete replication cycle in vitro. The products were found to be completely base-paired to their templates. The enzyme was able to use double-stranded RNA as a template for RNA synthesis if it could initiate from a single-stranded promoter. The inability (of most) of our enzyme preparations to create a single-stranded initiation site could explain why they could not perform a complete replication cycle in vitro. This is the first report on duplex RNA unwinding activities by a plant viral RdRp.
从感染苜蓿花叶病毒的烟草中纯化出的一种依赖RNA的RNA聚合酶（RdRp）能够在体外合成负链和正链的全长RNA。然而，该酶无法在体外完成完整的复制循环。研究发现，产物与它们的模板完全碱基配对。如果该酶能够从单链启动子起始，它就能将双链RNA用作RNA合成的模板。我们的大多数酶制剂无法产生单链起始位点，这可以解释为什么它们不能在体外完成完整的复制循环。这是关于植物病毒RdRp双链RNA解旋活性的首次报道。
