NEMO binding to polyubiquitin chains leads to the formation of liquid droplets
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Multivalent interactions between NEMO and polyubiquitin drive their phase condensation
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IKK is activated within the NEMO condensates
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Human disease-associated mutations of NEMO impair phase separation and IKK activation
Summary
The NF-κB essential modulator (NEMO) is a regulatory subunit of the IκB kinase (IKK) complex that phosphorylates the NF-κB inhibitors IκBs. NEMO mediates IKK activation by binding to polyubiquitin chains (polyUb). Here, we show that Lys63(K63)-linked or linear polyUb binding to NEMO robustly induced the formation of liquid-like droplets in which IKK was activated. This liquid phase separation of NEMO was driven by multivalent interactions between NEMO and polyUb. Both the NEMO ubiquitin-binding (NUB) domain and the zinc-finger (ZF) domain of NEMO mediated binding to polyUb and contributed to NEMO phase separation and IKK activation in cells. Moreover, NEMO mutations associated with human immunodeficiency impaired its phase separation. These results demonstrate that polyUb activates IKK and NF-κB signaling by promoting the phase separation of NEMO.
Graphical abstract
Keywords
ubiquitin
NEMO
IKK
NF-κB
liquid phase separation
inflammation
innate immunity
Data and code availability
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Original western blot images and microscopy data reported in this paper will be shared by the lead contact upon reasonable request.
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This paper does not report original code.
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Any additional information required to reanalyze the data reported in this paper is available from the lead contact upon reasonable request.