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Mol. Cell. Biol., 01 1995, 524-533, Vol 15, No. 1
JK Krady and DC Ward
The nonstructural protein NS-1, encoded by the parvovirus minute virus of
mice, is a potent regulator of viral gene expression. NS-1 does not bind
DNA in a sequence-specific manner, and the mechanism by which it modulates
viral promoter function is unclear. We have used Gal4-NS-1 fusion protein
constructs to identify and characterize an activating domain encoded within
the C-terminal 88 amino acids of NS-1 which competes effectively with the
acidic activator domain of the herpes simplex virus VP16 protein. DNA
affinity chromatography and immunoprecipitation experiments demonstrate
that protein-protein interactions between the transcription factor Sp1 and
NS-1 are required to bind NS-1 to promoter DNA in vitro. Cotransfection of
Gal4-NS-1 and Sp1-VP16 acidic activator constructs into Drosophila
melanogaster Schneider cells, which lack endogenous Sp1, stimulates
transcription from a minimal promoter containing five Gal4 binding sites,
while single-construct transfections do not. Cotransfection of Schneider
cells with wild-type NS-1 and Sp1 constructs activates transcription from a
simian virus 40 promoter 10- to 30-fold over that of either construct
alone. Thus, Sp1-NS-1 interactions in vivo can stimulate transcription from
a heterologous promoter containing Sp1 binding sites.
Copyright © 1995, American Society for Microbiology
Transcriptional activation by the parvoviral nonstructural protein NS-1 is mediated via a direct interaction with Sp1
Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06510.
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