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DNA binding and transcription activation by chicken interferon regulatory factor-3 (chIRF-3)
C E Grant1, D L May, R G Deeley
1Cancer Research Laboratories, Department of Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Nucleic Acids Research
|November 30, 2000
Summary
Chicken interferon regulatory factor 3 (chIRF-3) specifically binds interferon-stimulated response elements, acting as a dimer to activate gene expression. This transcription factor plays a key role in cellular responses to viral infections.
Area of Science:
- Molecular Biology
- Immunology
- Virology
Background:
- Interferon regulatory factors (IRFs) are crucial transcription factors mediating cellular responses to interferons and viral infections.
- An IRF, designated chIRF-3, was previously isolated from a chicken embryonic liver cDNA library.
Purpose of the Study:
- To characterize the DNA binding specificity of chicken IRF-3 (chIRF-3).
- To elucidate the dimerization and transcriptional activation properties of chIRF-3.
Main Methods:
- PCR-based binding site selection assay to determine optimal binding sites.
- Electrophoretic mobility shift assays (EMSAs) to compare binding specificity with IRF-1.
- Transfection experiments to assess promoter activation and map functional domains.
Main Results:
- chIRF-3 binds an optimal binding site (OBS) similar to the consensus interferon-stimulated response element (ISRE), but with higher specificity.
- chIRF-3 distinguishes itself from IRF-1 in ISRE binding and can bind inverted repeat motifs.
- chIRF-3 functions as a dimer, requiring amino acids 117-311 for protein-protein interaction.
- chIRF-3 activates promoters containing the OBS, with an activation domain mapped to amino acids 138-221.
Conclusions:
- chIRF-3 exhibits distinct DNA binding specificity compared to IRF-1.
- Dimerization is essential for chIRF-3 binding to DNA.
- chIRF-3 possesses potent transcriptional activation capabilities mediated by a specific domain.