Panne Daniel, McWhirter Sarah M, Maniatis Tom, Harrison Stephen C
Department of Biological Chemistry and Molecular Pharmacology, Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.
J Biol Chem. 2007 Aug 3;282(31):22816-22. doi: 10.1074/jbc.M703019200. Epub 2007 May 25.
The transcription factor interferon regulatory factor 3 (IRF-3) regulates genes in the innate immune response. IRF-3 is activated through phosphorylation by the kinases IKK epsilon and/or TBK1. Phosphorylation results in IRF-3 dimerization and removal of an autoinhibitory structure to allow interaction with the coactivators CBP/p300. The precise role of the different phosphorylation sites has remained controversial. Using purified proteins we show that TBK1 can directly phosphorylate full-length IRF-3 in vitro. Phosphorylation at residues in site 2 (Ser(396)-Ser(405)) alleviates autoinhibition to allow interaction with CBP (CREB-binding protein) and facilitates phosphorylation at site 1 (Ser(385) or Ser(386)). Phosphorylation at site 1 is, in turn, required for IRF-3 dimerization. The data support a two-step phosphorylation model for IRF-3 activation mediated by TBK1.
转录因子干扰素调节因子3（IRF-3）调控先天性免疫应答中的基因。IRF-3通过激酶IKKε和/或TBK1的磷酸化作用而被激活。磷酸化导致IRF-3二聚化并去除自身抑制结构，从而使其能够与共激活因子CBP/p300相互作用。不同磷酸化位点的确切作用一直存在争议。我们使用纯化蛋白表明，TBK1在体外可直接使全长IRF-3磷酸化。位点2（Ser(396)-Ser(405)）中的残基磷酸化可减轻自身抑制作用，从而使其能够与CBP（CREB结合蛋白）相互作用，并促进位点1（Ser(385)或Ser(386)）的磷酸化。反过来，位点1的磷酸化是IRF-3二聚化所必需的。这些数据支持由TBK1介导的IRF-3激活的两步磷酸化模型。
