Cloning of an inr- and E-box-binding protein, TFII-I, that interacts physically and functionally with USF1.
The transcription factor TFII-I has been shown to bind independently to two distinct promoter elements, a pyrimidine-rich initiator (Inr) and a recognition site (E-box) for upstream stimulatory factor 1 (USF1), and to stimulate USF1 binding to both of these sites. Here we describe the isolation of a cDNA encoding TFII-I and demonstrate that the corresponding 120 kDa polypeptide, when expressed ectopically, is capable of binding to both Inr and E-box elements. The primary structure of TFII-I reveals novel features that include six directly repeated 90 residue motifs that each possess a potential helix-loop/span-helix homology. These unique structural features suggest that TFII-I may have the capacity for multiple protein-protein and, potentially, multiple protein-DNA interactions. Consistent with this hypothesis and with previous in vitro studies, we further demonstrate that ectopic TFII-I and USF1 can act synergistically, and in some cases independently, to activate transcription in vivo through both Inr and the E-box elements of the adenovirus major late promoter. We also describe domains of USF1 that are necessary for its independent and synergistic activation functions.
Pubmed ID: 9384587 RIS Download
Adenoviridae | Amino Acid Sequence | Binding Sites | Cloning, Molecular | DNA, Complementary | DNA-Binding Proteins | Gene Expression Regulation | Genes, Reporter | HeLa Cells | Humans | Molecular Sequence Data | Promoter Regions, Genetic | Protein Binding | Recombinant Proteins | Repetitive Sequences, Nucleic Acid | Transcription Factors | Transfection | Upstream Stimulatory Factors