Abstract
LUBAC (linear ubiquitin chain assembly complex) activates the canonical NF-κB pathway through linear polyubiquitination of NEMO (NF-κB essential modulator, also known as IKKγ) and RIP1. However, the regulatory mechanism of LUBAC-mediated NF-κB activation remains elusive. Here, we show that A20 suppresses LUBAC-mediated NF-κB activation by binding linear polyubiquitin via the C-terminal seventh zinc finger (ZF7), whereas CYLD suppresses it through deubiquitinase (DUB) activity. We determined the crystal structures of A20 ZF7 in complex with linear diubiquitin at 1.70-1.98 Å resolutions. The crystal structures revealed that A20 ZF7 simultaneously recognizes the Met1-linked proximal and distal ubiquitins, and that genetic mutations associated with B cell lymphomas map to the ubiquitin-binding sites. Our functional analysis indicated that the binding of A20 ZF7 to linear polyubiquitin contributes to the recruitment of A20 into a TNF receptor (TNFR) signalling complex containing LUBAC and IκB kinase (IKK), which results in NF-κB suppression. These findings provide new insight into the regulation of immune and inflammatory responses.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Crystallography, X-Ray
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DNA-Binding Proteins / chemistry
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Deubiquitinating Enzyme CYLD
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HEK293 Cells
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Humans
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I-kappa B Kinase / metabolism
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Intracellular Signaling Peptides and Proteins / chemistry
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Intracellular Signaling Peptides and Proteins / genetics
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Intracellular Signaling Peptides and Proteins / metabolism*
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Lymphoma, B-Cell / genetics
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Mutation
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NF-kappa B / metabolism*
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Nuclear Proteins / chemistry
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Polyubiquitin / biosynthesis
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Protein Binding / genetics
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Protein Conformation
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Receptors, Tumor Necrosis Factor / chemistry
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Receptors, Tumor Necrosis Factor / metabolism
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Signal Transduction / drug effects
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Signal Transduction / physiology
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Tumor Necrosis Factor alpha-Induced Protein 3
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Tumor Suppressor Proteins / metabolism
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Ubiquitin / chemistry
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Ubiquitin / metabolism
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Zinc Fingers / physiology*
Substances
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DNA-Binding Proteins
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Intracellular Signaling Peptides and Proteins
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NF-kappa B
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Nuclear Proteins
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Receptors, Tumor Necrosis Factor
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Tumor Suppressor Proteins
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Ubiquitin
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Polyubiquitin
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I-kappa B Kinase
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CYLD protein, human
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Deubiquitinating Enzyme CYLD
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TNFAIP3 protein, human
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Tumor Necrosis Factor alpha-Induced Protein 3
Associated data
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PDB/3VUW
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PDB/3VUX
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PDB/3VUY