title: OTULIN antagonizes LUBAC signaling by specifically hydrolyzing Met1-linked polyubiquitin.
abstract: The linear ubiquitin (Ub) chain assembly complex (LUBAC) is an E3 ligase that specifically assembles Met1-linked (also known as linear) Ub chains that regulate nuclear factor κB (NF-κB) signaling. Deubiquitinases (DUBs) are key regulators of Ub signaling, but a dedicated DUB for Met1 linkages has not been identified. Here, we reveal a previously unannotated human DUB, OTULIN (also known as FAM105B), which is exquisitely specific for Met1 linkages. Crystal structures of the OTULIN catalytic domain in complex with diubiquitin reveal Met1-specific Ub-binding sites and a mechanism of substrate-assisted catalysis in which the proximal Ub activates the catalytic triad of the protease. Mutation of Ub Glu16 inhibits OTULIN activity by reducing kcat 240-fold. OTULIN overexpression or knockdown affects NF-κB responses to LUBAC, TNFα, and poly(I:C) and sensitizes cells to TNFα-induced cell death. We show that OTULIN binds LUBAC and that overexpression of OTULIN prevents TNFα-induced NEMO association with ubiquitinated RIPK1. Our data suggest that OTULIN regulates Met1-polyUb signaling.
authors.affiliation: Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, UK.
authors.forename: Kirstin
authors.initials: K
authors.lastname: Keusekotten
authors.forename: Paul Ronald
authors.initials: PR
authors.lastname: Elliott
authors.forename: Laura
authors.initials: L
authors.lastname: Glockner
authors.forename: Berthe Katrine
authors.initials: BK
authors.lastname: Fiil
authors.forename: Rune Busk
authors.initials: RB
authors.lastname: Damgaard
authors.forename: Yogesh
authors.initials: Y
authors.lastname: Kulathu
authors.forename: Tobias
authors.initials: T
authors.lastname: Wauer
authors.forename: Manuela Kathrin
authors.initials: MK
authors.lastname: Hospenthal
authors.forename: Mads
authors.initials: M
authors.lastname: Gyrd-Hansen
authors.forename: Daniel
authors.initials: D
authors.lastname: Krappmann
authors.forename: Kay
authors.initials: K
authors.lastname: Hofmann
authors.forename: David
authors.initials: D
authors.lastname: Komander
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002384:Catalysis; D018360:Crystallography, X-Ray; D016207:Cytokines / Q000378:metabolism; D010450:Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D025821:Polyubiquitin / Q000096:biosynthesis; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D015398:Signal Transduction
chemical_list: D016207:Cytokines; D025821:Polyubiquitin; D010450:Endopeptidases; C582107:OTULIN protein, human