Crystallographic Characterization of the DNA-Binding Domain of Interferon Regulatory Factor-2 Complexed with DNA

• Published in: Journal of structural biology 1998, Vol.121 (3), p.363-366
• Main Authors: Kusumoto, Masahiro, Fujii, Yoshifumi, Tsukuda, Yuko, Ohira, Takeshi, Kyougoku, Yoshimasa, Taniguchi, Tadatsugu, Hakoshima, Toshio
• Format: Article
• Language: English
• Subjects: immune system; IRF-2; molecular recognition; transcription factor; X-ray diffraction
• ISSN: 1047-8477; 1095-8657
• DOI: 10.1006/jsbi.1998.3970

Interferon regulatory factors (IRFs) are transcription factors for interferon-related genes, which manifest both antiviral and tumor-suppressor activities and regulate cell growth in response to DNA damage. For the transcription initiation of the interferon-β gene, IRFs form a macromolecular assembly bound to the promoter DNA, referred to as an enhancesome, together with several other transcription factors and DNA-binding proteins. The three-dimensional structure of IRF–DNA complex would provide insights into the structure and function of the enhancesome. In this study, we crystallized the DNA-binding domain of interferon regulatory factor-2 complexed with a DNA fragment. The crystals reproducibly grew by the vapor diffusion technique with 2-methyl-pentanediol from solutions containing small detergents, such asn-octyl-β-d-glucoside. Cryocrystallographic experiments showed that crystals belong to space groupP212121witha= 90.66 Å,b= 101.01 Å,c= 171.58 Å and diffract up to 2.8 Å resolution. The absorption measurements of a solution in which the crystals were dissolved indicate that the DNA-binding domain binds to the DNA as a dimer. The calculated values of the solvent contents suggest that the protein–DNA complexes form a multimer in the crystal. These features may reflect the association of the complexes in the enhancesome.