Ser386 phosphorylation of transcription factor IRF-3 induces dimerization and association with CBP/p300 without overall conformational change.
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.
Takahasi
Kiyohiro
K
Department of Structural Biology, Graduate School of Pharmaceutical Sciences, Hokkaido University, N-12W-6 Kita-ku, Sapporo 060-0812, Japan.
Horiuchi
Masataka
M
Fujii
Kiyonaga
K
Nakamura
Shingo
S
Noda
Nobuo N
NN
Yoneyama
Mitsutoshi
M
Fujita
Takashi
T
Inagaki
Fuyuhiko
F
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*
C494232:IRF3 protein, human; D050838:Interferon Regulatory Factor-3; D012694:Serine; D050880:p300-CBP Transcription Factors