Ser386 phosphorylation of transcription factor IRF-3 induces dimerization and association with CBP/p300 without overall conformational change.
Takahasi, K., Horiuchi, M., Fujii, K., Nakamura, S., Noda, N.N., Yoneyama, M., Fujita, T., Inagaki, F.(2010) Genes Cells 15: 901-910
- PubMed: 20604809 
- DOI: https://doi.org/10.1111/j.1365-2443.2010.01427.x
- Primary Citation of Related Structures:  
3A77 - PubMed Abstract: 
The transcription factor IRF-3 is activated by microbial invasions and produces a variety of cytokines including type-I interferon. Upon microbial infection, IRF-3 is phosphorylated at its C-terminal regulatory domain, then oligomerized, translocated into the nucleus, and here it binds to CBP/p300. Although a number of studies have been reported investigating the activation mechanism of IRF-3, there are a number of unresolved issues, especially on the phosphorylation sites, the oligomerization process and the binding mechanism with CBP/p300. In this report, the phosphorylated IRF-3 regulatory domain (IRF-3 RD) was prepared using the kinase IKK-i, and the active form of phosphorylated IRF-3 RD was identified. The paper also reports the crystal structure of the active form of the phosphorylated IRF-3 RD. Furthermore, the phosphorylation of Ser386 was found to be essential for its dimerization and binding with CBP/p300 using mutational analysis and mass spectrometry. Thus, we conclude that the phosphorylation of Ser386 is essential for activation of IRF-3.
Organizational Affiliation: 
Department of Structural Biology, Graduate School of Pharmaceutical Sciences, Hokkaido University, N-12W-6 Kita-ku, Sapporo 060-0812, Japan.