Analysis of the mechanisms of tomato mosaic virus RNA replication complex formation

番茄花叶病毒(ToMV)RNA的高效增殖需要一个宿主七通跨膜蛋白TOM1和一个小的GTP结合蛋白ARL8。当用抽提的植物原生质体提取物进行ToMV RNA复制反应时，用不含这两种蛋白质的拟南芥膜进行体外复制反应时，几乎检测不到负链RNA的合成。当ToMV的复制蛋白与TOM1和ARL8共表达时，这些蛋白具有鸟苷酰转移酶的活性，但不能催化ToMV的RNA复制。因此，与含有TOM1和ARL8的膜相互作用可以使ToMV复制蛋白具有鸟苷酰转移酶活性，但不足以激活其RNA聚合酶活性。

A host seven-pass transmembrane protein TOM1 and a small GTP-binding protein ARL8 are required for efficient multiplication of tomato mosaic virus(ToMV) RNA. When in vitro ToMV RNA replication reactions using evacuolated plant protoplast extracts were performed using Arabidopsis thaliana membranes that lack either one of these proteins, negative-strand RNA synthesis was hardly detectable. When the replication protein of ToMV was co-expressed with TOM1 and ARL8, the proteins gained guanylyltransferase activity, but could not catalize ToMV RNA replication. Thus, interaction with TOM1-and ARL8-containing membranes confers guanylyltransferase activity to ToMV replication protein, however, it is not sufficient for the activation of its RNA polymerase activity.