Expression and function of structural proteins of paramyxovirus transcription complex

人副流感病毒2型（hPIV2）的V基因转录成V和P mRNA，是副粘病毒的一个成员。V mRNA是V基因的忠实转录物，而P mRNA在感染hpiv2的哺乳动物细胞中通过RNA编辑机制进行转录。因此P蛋白和V蛋白都在细胞中被翻译。我们构建了含有原V基因的重组杆状病毒，原V基因在其编辑位点上有7个G残基，而经过修饰的V基因在其编辑位点上有10个G残基。意外的是，在重组杆状病毒感染的昆虫细胞中表达V基因时，除了V蛋白外，还合成了少量的P蛋白。此外，当在昆虫细胞中表达含有V基因的重组杆状病毒时，P蛋白的合成增加，该基因在其编辑位点上具有延长的G残基延伸长度，即10个G残基。通过体外翻译杆状病毒感染细胞的mRNA合成了P蛋白和V蛋白。此外，在mRNA中检测到g -残基插入和缺失。而T7 RNA聚合酶体外转录的V RNA在体外翻译中未检测到P蛋白。这些结果表明，在没有副粘病毒L蛋白的转录水平上，未模板化的G残基被插入和删除。

V gene of human parainfluenza virus type 2 (hPIV2) , a member of paramyxoviruses, is transcribed into both a V and a P mRNA.The V mRNA is a faithful transcript of the V gene, however the P mRNA is transcribed by RNA editing mechanism in hPIV2-infected mammalian cells. Thus both the P and the V proteins are translated in the cells. We constructed recombinant baculoviruses containing the original V gene, which has seven G residues at its editing site and a manipulated V gene, which has ten G residues at its editing site. Unexpectedly, a small amount of the P protein was synthesized in addition to the V protein when the V gene was expressed in the recombinant baculovirus-infected insect cells. Furthermore, synthesis of the P protein increased when a recombinant baculovirus containing a V gene, which has extended length of G residue atretch, that is ten G residues, at its editing site, was expressed in the insect cells. Both the P and the V proteins were synthesized in in vitro translation of mRNA from the recombinant baculovirus-infected cells. Moreover, both G-residue insertions and a deletion were detected in mRNA.While the P protein was not detected in in vitro translation of the V RNA that was transcribed in vitro by T7 RNA polymerase. These results suggest that the non-templated G residues were inserted and deleted at the transcription level without paramyxovirus L protein.