Mouse interferon regulatory factor-2: expression, purification and DNA binding activity

Interferon regulatory factor-2 (IRF-2) is a mammalian transcription factor for Interferon and Interferon inducible genes; biologically, plays an important role in cell growth regulation and has been shown to be a potential oncogene. We have expressed, purified recombinant Murine IRF-2 (349 amino acid) as a GST (Glutathione-S-Transferase)-IRF-2 soluble fusion protein in E. coli XL-1 blue cells. Recombinant GST-IRF-2 was biologically active in terms of its DNA binding activity with IRF-E oligo (GAAAGT)(4). GST-alone expressed from the vector did not bind to it. We observed five different molecular mass complexes of GST-IRF-2/DNA (1-5) with IRF-E, which were competed out by 100x-fold molar excess of IRF-E, suggesting that the complexes were specific for IRF-2. Such GAAANN (N = any nucleotide) hexa nucleotides occur in the promoters of many virus and interferon-inducible mammalian genes. Multimeric GAAAGT/C sequences are inducible by virus, IFN, dsRNA and IRF-1/2. Multiple GST-IRF-2/DNA complexes may be helpful to understand the mechanism of DNA binding activity of IRF-2.