Activation of the canonical IKK complex by K63/M1-linked hybrid ubiquitin chains

Christoph H. Emmerich, Alban Ordureau, Sam Strickson, J. Simon C. Arthur, Patrick G. A. Pedrioli, David Komander, Philip Cohen (Lead / Corresponding author)

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    Polyubiquitin (pUb) chains formed between the C terminus of ubiquitin and lysine 63 (K63) or methionine 1 (M1) of another ubiquitin have been implicated in the activation of the canonical I?B kinase (IKK) complex. Here, we demonstrate that nearly all of the M1-pUb chains formed in response to interleukin-1, or the Toll-Like Receptors 1/2 agonist PamCSK , are covalently attached to K63-pUb chains either directly as K63-pUb/M1-pUb hybrids or indirectly by attachment to the same protein. Interleukin-1 receptor (IL-1R)-associated kinase (IRAK) 1 is modified first by K63-pUb chains to which M1-pUb linkages are added subsequently, and myeloid differentiation primary response gene 88 (MyD88) and IRAK4 are also modified by both K63-pUb and M1-pUb chains. We show that the heme-oxidized IRP2 ubiquitin ligase 1 interacting protein (HOIP) component of the linear ubiquitin assembly complex catalyzes the formation of M1-pUb chains in response to interleukin-1, that the formation of K63-pUb chains is a prerequisite for the formation of M1-pUb chains, and that HOIP interacts with K63-pUb but not M1-pUb linkages. These findings identify K63-Ub oligomers as a major substrate of HOIP in cells where the MyD88-dependent signaling network is activated. The TGFbeta-activated kinase 1 (TAK1)-binding protein (TAB) 2 and TAB3 components of the TAK1 complex and the NF?B Essential Modifier (NEMO) component of the canonical IKK complex bind to K63-pUb chains and M1-pUb chains, respectively. The formation of K63/M1-pUb hybrids may therefore provide an elegant mechanism for colocalizing both complexes to the same pUb chain, facilitating the TAK1-catalyzed activation of IKKa and IKKß. Our study may help to resolve the debate about the relative importance of K63-pUb and M1-pUb chains in activating the canonical IKK complex.
    Original languageEnglish
    Pages (from-to)15247-15252
    Number of pages6
    JournalProceedings of the National Academy of Sciences of the United States of America
    Issue number38
    Publication statusPublished - 17 Sept 2013


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