Abstract
The human cytomegalovirus IE2 is a sequence-specific DNA-binding protein. A consensus IE2-binding site (IBS) contains two copies of the dinucleotide CG separated by 10 not well-conserved but AT-rich nucleotides. In this report, we demonstrated that the TATA box of the insulin-like growth factor binding protein 4 (IGFBP4) promoter is embedded in an IBS. In a transient transfection study, IE2-mediated repression of a reporter driven either by a synthetic promoter containing the IGFBP4 TATA/IBS element or by the native IGFBP4 promoter was dependent on the intactness of the IBS. Competition with TBP for binding to the IGFBP4 TATA/IBS element may underlie the mechanism for the IE2-mediated repression, because IE2 and TATA box-binding protein (TBP) binding to the IGFBP4 TATA/IBS element are mutually elusive. Moreover, the TATA boxes of several other genes, including ADA and CPH-70, are likewise confined in IBS-like sequences. The IE2 interacts with those TATA/IBS elements in vitro and inhibits transcription driven by them in vivo, supporting the idea that competitive inhibition of TBP binding to the TATA box represents a novel mechanism exploited by IE2 to repress cellular gene expression.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Binding Sites
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Binding, Competitive
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Chloramphenicol O-Acetyltransferase / genetics
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Chloramphenicol O-Acetyltransferase / metabolism
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Electrophoresis, Polyacrylamide Gel
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Gene Expression Regulation
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Humans
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Immediate-Early Proteins / genetics
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Immediate-Early Proteins / metabolism*
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Insulin-Like Growth Factor Binding Protein 4 / genetics
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Insulin-Like Growth Factor Binding Protein 4 / metabolism
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Membrane Glycoproteins*
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Oligonucleotides / genetics
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Oligonucleotides / metabolism
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Plasmids
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Promoter Regions, Genetic / genetics*
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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TATA Box*
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TATA-Box Binding Protein
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Trans-Activators*
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Transcription Factors / genetics
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Transcription Factors / metabolism*
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Transcription, Genetic
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Transfection
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Tumor Cells, Cultured
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Viral Envelope Proteins*
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Viral Proteins*
Substances
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DNA-Binding Proteins
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IE2 protein, Cytomegalovirus
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Immediate-Early Proteins
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Insulin-Like Growth Factor Binding Protein 4
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Membrane Glycoproteins
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Oligonucleotides
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Recombinant Fusion Proteins
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TATA-Box Binding Protein
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Trans-Activators
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Transcription Factors
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UL115 protein, Human herpesvirus 5
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Viral Envelope Proteins
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Viral Proteins
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glycoprotein H, Cytomegalovirus
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glycoprotein H, Human cytomegalovirus
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glycoprotein O, cytomegalovirus
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Chloramphenicol O-Acetyltransferase