The IRAK-catalysed activation of the E3 ligase function of Pellino isoforms induces the Lys63-linked polyubiquitination of IRAK1

Alban Ordureau , Hilary Smith , Mark Windheim , Mark Peggie , Emma Carrick , Nick Morrice , Philip Cohen (1)

1 MRC Protein Phosphorylation Unit

The protein kinases IRAK1 and IRAK4 play key roles in a signalling pathway by which bacterial infection or interleukin-1 trigger the production of inflammatory mediators. Here we demonstrate that IRAK1 and IRAK4 phosphorylate Pellino isoforms in vitro and that phosphorylation greatly enhances Pellino's E3 ubiquitin ligase activity. We show that, in vitro, Pellino 1 can combine with the E2 conjugating complex Ubc13-Uev1a to catalyse the formation of Lys63-linked polyubiquitin (K63-pUb) chains, with UbcH3 to catalyse the formation of K48-pUb chains and with UbcH4, UbcH5a or UbcH5b to catalyse the formation of pUb-chains linked mainly via K11 and K48 of ubiquitin. In IRAK1-/- cells, the co-transfection of DNA encoding wild type IRAK1 and Pellino 2, but not inactive mutants of these proteins, induces the formation of K63-pUb-IRAK1 and its interaction with the NEMO regulatory subunit of the IKK complex, a K63-pUb-binding protein. These studies suggest that Pellino isoforms may be the E3 ubiquitin ligases that mediate the IL-1-stimulated formation of K63-pUb-IRAK1 in cells, which may contribute to the activation of IKKβ and the transcription factor NFκB as well as other signalling pathways dependent on IRAK1/4.

Mots clés: Life Sciences

Alban Ordureau, Hilary Smith, Mark Windheim, Mark Peggie, Emma Carrick, et al.. The IRAK-catalysed activation of the E3 ligase function of Pellino isoforms induces the Lys63-linked polyubiquitination of IRAK1. Biochemical Journal, 2007, 409 (1), pp.43-52. ⟨10.1042/BJ20071365⟩. ⟨hal-00478890⟩