Molecular Cloning and Characterization of Interferon αβ Response Element Binding Factors of the Murine (2'-5')Oligoadenylate Synthetase ME-12 Gene

Seven clones encoding interferon response element binding factors have been isolated from a mouse fibroblast lambda gt11 cDNA library by using a 32P end-labeled tandem trimer of the mouse (2'-5')oligoadenylate synthetase gene interferon response element as a probe. Clone 16 shares strong similarity (95%) at both DNA and amino acid level with YB-1, a human major histocompatibility complex class II Y-box DNA-binding protein, and with dbpB, a human epidermal growth factor receptor gene enhancer region binding protein. The product of the gene represented by clone 16 may represent a factor that regulates multiple genes by binding to a variety of 5' regulatory elements. Clone 25 is a 2407-base-pair-long cDNA and contains a putative 311-amino acid open reading frame corresponding to an estimated mass of 35.5 kDa. This putative protein, designated as interferon response element binding factor 1 (IREBF-1), contains an acidic domain, three heptad repeat leucine arrays, and a region that shares similarity with the yeast transcriptional factor GAL4 DNA-binding domain. Furthermore, the C terminus of IREBF-1 shows an unusual amphipathic property: within a 79-amino acid range, one side of the alpha-helical region contains a preponderance of hydrophobic amino acids and the other side contains hydrophilic amino acids. This type of structure provides a strong hydrophobic force for protein-protein interaction.