期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1998
卷号：95
期号：4
页码：1449-1454
DOI：10.1073/pnas.95.4.1449
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：An RNA-dependent RNA polymerase is packaged within the virions of purified vesicular stomatitis virus, a nonsegmented negative-strand RNA virus, which carries out transcription of the genome RNA into mRNAs both in vitro and in vivo. The RNA polymerase is composed of two virally encoded polypeptides: a large protein L (240 kDa) and a phosphoprotein P (29 kDa). Recently, we obtained biologically active L protein from insect cells following infection by a recombinant baculovirus expressing L gene. During purification of the L protein from Sf21 cells, we obtained in addition to an active L fraction an inactive fraction that required uninfected insect cell extract to restore its activity. The cellular factors have now been purified, characterized, and shown to be {beta} and {gamma} subunits of the protein synthesis elongation factor EF-1. We also demonstrate that the subunit of EF-1 remains tightly bound to the L protein in the inactive fraction and {beta}{gamma} subunits associate with the L() complex. Further purification of L() from the inactive fraction revealed that the complex is partially active and is significantly stimulated by the addition of {beta}{gamma} subunits purified from Sf21 cells. A putative inhibitor(s) appears to co-elute in the inactive fraction that blocked the L() activity. The purified virions also package all three subunits of EF-1. These findings have a striking similarity with Q{beta} RNA phage, which also associates with the bacterial homologue of EF-1 for its replicase function, implicating a possible evolutionary relationship between these host proteins and the RNA-dependent RNA polymerase of RNA viruses.
