Transcriptional activation by simian virus 40 large T antigen: interactions with multiple components of the transcription complex.
Simian virus 40 (SV40) large T antigen is a potent transcriptional activator of both viral and cellular promoters. Within the SV40 late promoter, a specific upstream element necessary for T-antigen transcriptional activation is the binding site for transcription-enhancing factor 1 (TEF-1). The promoter structure necessary for T-antigen-mediated transcriptional activation appears to be simple. For example, a promoter consisting of upstream TEF-1 binding sites (or other factor-binding sites) and a downstream TATA or initiator element is efficiently activated. It has been demonstrated that transcriptional activation by T antigen does not require direct binding to the DNA; thus, the most direct effect that T antigen could have on these simple promoters would be through protein-protein interactions with either upstream-bound transcription factors, the basal transcription complex, or both. To determine whether such interactions occur, full-length T antigen or segments of it was fused to the glutathione-binding site (GST fusions) or to the Gal4 DNA-binding domain (amino acids 1 to 147) (Gal4 fusions). With the GST fusions, it was found that TEF-1 and the TATA-binding protein (TBP) bound different regions of T antigen. A GST fusion containing amino acids 5 to 172 (region T1) efficiently bound TBP. TEF-1 bound neither region T1 nor a region between amino acids 168 and 373 (region T2); however, it bound efficiently to the combined region (T5) containing amino acids 5 to 383.(ABSTRACT TRUNCATED AT 250 WORDS)
Gruda
M C
MC
Department of Microbiology, School of Medicine, University of Pennsylvania, Philadelphia 19104-6142.
Zabolotny
J M
JM
Xiao
J H
JH
Davidson
I
I
Alwine
J C
JC
D000818:Animals; D000957:Antigens, Viral, Tumor / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002522:Chlorocebus aethiops; D004247:DNA; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism; D005786:Gene Expression Regulation; D005978:Glutathione / Q000378:metabolism; D051863:Host Cell Factor C1; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D050811:Octamer Transcription Factor-1; D011401:Promoter Regions, Genetic; D029701:Saccharomyces cerevisiae Proteins; D016385:TATA Box; D035181:TATA-Box Binding Protein; D000091262:TEA Domain Transcription Factors; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D000957:Antigens, Viral, Tumor; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C052130:GAL4 protein, S cerevisiae; D051863:Host Cell Factor C1; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D050811:Octamer Transcription Factor-1; D029701:Saccharomyces cerevisiae Proteins; D035181:TATA-Box Binding Protein; D000091262:TEA Domain Transcription Factors; C057182:TEAD1 protein, human; D014157:Transcription Factors; D004247:DNA; D005978:Glutathione