title: Ser386 phosphorylation of transcription factor IRF-3 induces dimerization and association with CBP/p300 without overall conformational change.
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.
authors.affiliation: Department of Structural Biology, Graduate School of Pharmaceutical Sciences, Hokkaido University, N-12W-6 Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Kiyohiro
authors.initials: K
authors.lastname: Takahasi
authors.forename: Masataka
authors.initials: M
authors.lastname: Horiuchi
authors.forename: Kiyonaga
authors.initials: K
authors.lastname: Fujii
authors.forename: Shingo
authors.initials: S
authors.lastname: Nakamura
authors.forename: Nobuo N
authors.initials: NN
authors.lastname: Noda
authors.forename: Mitsutoshi
authors.initials: M
authors.lastname: Yoneyama
authors.forename: Takashi
authors.initials: T
authors.lastname: Fujita
authors.forename: Fuyuhiko
authors.initials: F
authors.lastname: Inagaki
mesh_terms: D006801:Humans; D050838:Interferon Regulatory Factor-3 / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D011487:Protein Conformation; D055503:Protein Multimerization; D012694:Serine / Q000737:chemistry / Q000378:metabolism*; D015533:Transcriptional Activation; D050880:p300-CBP Transcription Factors / Q000737:chemistry* / Q000378:metabolism*
chemical_list: C494232:IRF3 protein, human; D050838:Interferon Regulatory Factor-3; D012694:Serine; D050880:p300-CBP Transcription Factors