Functional analysis of a liver-specific enhancer of the hepatitis B virus.
The liver-specific enhancer I of the human hepatitis B virus contains several regions of DNA-protein interaction. Located within this element are also the domains of a promoter controlling the synthesis of the X open reading frame. Functional domains of the enhancer I and the X gene promoter were identified using DNase I protection analysis, deletion mutagenesis, and cell transfections. A unique liver-specific interaction was identified within this element whose binding site includes a direct sequence repeat, 5'-AGTAAACAGTA-3'. The factor(s) binding to this sequence motif was purified by oligonucleotide-affinity chromatography. Binding of this factor appears to play a key role in determining the overall enhancer function. Additionally, the interaction of several purified factors is presented. Cotransfection of liver cells with expression vectors encoding transcriptional factors resulted in trans-activation of the promoter/enhancer function. Based on the results of genetic analysis a model outlining the functional domains of the enhancer/promoter region is presented.
Trujillo
M A
MA
Department of Microbiology and Immunology, University of Colorado Medical School, Denver 80262.
Letovsky
J
J
Maguire
H F
HF
Lopez-Cabrera
M
M
Siddiqui
A
A
D022762:CCAAT-Enhancer-Binding Proteins; D004252:DNA Mutational Analysis; D004279:DNA, Viral / Q000235:genetics; D004268:DNA-Binding Proteins / Q000502:physiology; D004742:Enhancer Elements, Genetic; D015967:Gene Expression Regulation, Viral; D005814:Genes, Viral; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D066298:In Vitro Techniques; D008099:Liver / Q000502:physiology; D009687:Nuclear Proteins / Q000502:physiology; D011401:Promoter Regions, Genetic; D016755:Proto-Oncogene Proteins c-jun; D012045:Regulatory Sequences, Nucleic Acid; D014157:Transcription Factors / Q000502:physiology; D014158:Transcription, Genetic; D015678:Viral Structural Proteins / Q000235:genetics
D022762:CCAAT-Enhancer-Binding Proteins; D004279:DNA, Viral; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D016755:Proto-Oncogene Proteins c-jun; D014157:Transcription Factors; D015678:Viral Structural Proteins