Structure of the A20 OTU domain and mechanistic insights into deubiquitination.
The NF-kappaB (nuclear factor kappaB) regulator A20 antagonises IKK [IkappaB (inhibitor of kappaB) kinase] activation by modulating Lys63-linked polyubiquitination of cytokine-receptor-associated factors including TRAF2/6 (tumour-necrosis-factor-receptor-associated factor 2/6) and RIP1 (receptor-interacting protein 1). In the present paper we describe the crystal structure of the N-terminal OTU (ovarian tumour) deubiquitinase domain of A20, which differs from other deubiquitinases but shares the minimal catalytic core with otubain-2. Analysis of conserved surface regions allows prediction of ubiquitin-binding sites for the proximal and distal ubiquitin molecules. Structural and biochemical analysis suggests a novel architecture of the catalytic triad, which might be present in a subset of OTU domains including Cezanne and TRABID (TRAF-binding domain). Biochemical analysis shows a preference of the isolated A20 OTU domain for Lys48-linked tetraubiquitin in vitro suggesting that additional specificity factors might be required for the physiological function of A20 in cells.
Komander
David
D
Section of Structural Biology, The Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW3 6JB, UK. david.komander@icr.ac.uk
Barford
David
D
D000595:Amino Acid Sequence; D001671:Biochemistry / Q000379:methods; D002384:Catalysis; D020134:Catalytic Domain; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D008239:Lysine / Q000737:chemistry; D008969:Molecular Sequence Data; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins / Q000378:metabolism; D013869:Thiolester Hydrolases / Q000737:chemistry*; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D025801:Ubiquitin / Q000737:chemistry*
C119724:AGFG1 protein, human; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D025801:Ubiquitin; D051550:I-kappa B Kinase; C496399:OTUB2 protein, human; D013869:Thiolester Hydrolases; C076529:TNFAIP3 protein, human; D000072598:Tumor Necrosis Factor alpha-Induced Protein 3; D008239:Lysine