抄録
The Baculovirus immediate-early gene ie1 product IE1 is a viral regulatory protein of nucleopolyhedrovirus (NPV) and acts as an essential transactivator in viral replication. In this study, IE1-transactivation of promoters in mammalian cells was examined using the Bombyx mori (Bm) NPV ie1 (Bie1), BmNPV p35 (Bp35), Drosophila melanogaster heat-shock protein 70 (Dhsp), Drosophila melanogaster elongation factor 1 alpha (Delf) and SV40 early (SV40e) promoters. It was demonstrated that BmNPV IE1 could transactivate the Bie1 promoter in BHK cells approximately 2-fold as well as in insect cells. The deletion mutant analysis revealed that only the core promoter region (from the TATA-box to CAGT initiation motif) of Bie1 was required for hrs-independent transactivation by IE1 in BHK cells. Furthermore, IE1-transactivation of core promoters both in BHK cells and in Vero cells was demonstrated for the Dhsp, Delf and SV40e promoters. These results suggest that baculovirus IE1 maintains the potential for transactivation of the core promoter in mammalian cells although flanking sequences may prevent it.
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