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From Proteopedia
STRUCTURE OF DDB1-DDB2-CUL4A-RBX1 BOUND TO A 12 BP ABASIC SITE CONTAINING DNA-DUPLEX
Structural highlights
Function[DDB2_DANRE] Required for DNA repair. Binds to ddb1 to form the UV-damaged DNA-binding protein complex (the UV-DDB complex). The UV-DDB complex may recognize UV-induced DNA damage and recruit proteins of the nucleotide excision repair pathway (the NER pathway) to initiate DNA repair. Also appears to function as the substrate recognition module for a DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complex which may ubiquitinate histone H2A, histone H3 and histone H4 at sites of UV-induced DNA damage. The ubiquitination of histones may facilitate their removal from the nucleosome and promote subsequent DNA repair (By similarity). [CUL4A_HUMAN] Core component of multiple cullin-RING-based E3 ubiquitin-protein ligase complexes which mediate the ubiquitination and subsequent proteasomal degradation of target proteins. As a scaffold protein may contribute to catalysis through positioning of the substrate and the ubiquitin-conjugating enzyme. The E3 ubiquitin-protein ligase activity of the complex is dependent on the neddylation of the cullin subunit and is inhibited by the association of the deneddylated cullin subunit with TIP120A/CAND1. The functional specificity of the E3 ubiquitin-protein ligase complex depends on the variable substrate recognition component. DCX(DET1-COP1) directs ubiquitination of JUN. DCX(DDB2) directs ubiquitination of XPC. In association with RBX1, DDB1 and DDB2 is required for histone H3 and histone H4 ubiquitination in response to ultraviolet and may be important for subsequent DNA repair. DCX(DTL) plays a role in PCNA-dependent polyubiquitination of CDT1 and MDM2-dependent ubiquitination of TP53 in response to radiation-induced DNA damage and during DNA replication. In association with DDB1 and SKP2 probably is involved in ubiquitination of CDKN1B/p27kip. Is involved in ubiquitination of HOXA9.[1] [2] [3] [4] [5] [6] [DDB1_HUMAN] Required for DNA repair. Binds to DDB2 to form the UV-damaged DNA-binding protein complex (the UV-DDB complex). The UV-DDB complex may recognize UV-induced DNA damage and recruit proteins of the nucleotide excision repair pathway (the NER pathway) to initiate DNA repair. The UV-DDB complex preferentially binds to cyclobutane pyrimidine dimers (CPD), 6-4 photoproducts (6-4 PP), apurinic sites and short mismatches. Also appears to function as a component of numerous distinct DCX (DDB1-CUL4-X-box) E3 ubiquitin-protein ligase complexes which mediate the ubiquitination and subsequent proteasomal degradation of target proteins. The functional specificity of the DCX E3 ubiquitin-protein ligase complex is determined by the variable substrate recognition component recruited by DDB1. DCX(DDB2) (also known as DDB1-CUL4-ROC1, CUL4-DDB-ROC1 and CUL4-DDB-RBX1) may ubiquitinate histone H2A, histone H3 and histone H4 at sites of UV-induced DNA damage. The ubiquitination of histones may facilitate their removal from the nucleosome and promote subsequent DNA repair. DCX(DDB2) also ubiquitinates XPC, which may enhance DNA-binding by XPC and promote NER. DCX(DTL) plays a role in PCNA-dependent polyubiquitination of CDT1 and MDM2-dependent ubiquitination of TP53 in response to radiation-induced DNA damage and during DNA replication. DCX(ERCC8) (the CSA complex) plays a role in transcription-coupled repair (TCR). May also play a role in ubiquitination of CDKN1B/p27kip when associated with CUL4 and SKP2.[7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [RBX1_MOUSE] E3 ubiquitin ligase component of multiple cullin-RING-based E3 ubiquitin-protein ligase complexes which mediate the ubiquitination and subsequent proteasomal degradation of target proteins, including proteins involved in cell cycle progression, signal transduction, transcription and transcription-coupled nucleotide excision repair. The functional specificity of the E3 ubiquitin-protein ligase complexes depends on the variable substrate recognition components. As a component of the CSA complex promotes the ubiquitination of ERCC6 resulting in proteasomal degradation (By similarity). Through the RING-type zinc finger, seems to recruit the E2 ubiquitination enzyme, like CDC34, to the complex and brings it into close proximity to the substrate. Probably also stimulates CDC34 autoubiquitination. May be required for histone H3 and histone H4 ubiquitination in response to ultraviolet and for subsequent DNA repair. Promotes the neddylation of CUL1, CUL2, CUL4 and CUL4 via its interaction with UBE2M (By similarity).[23] Publication Abstract from PubMedThe DDB1-CUL4-RBX1 (CRL4) ubiquitin ligase family regulates a diverse set of cellular pathways through dedicated substrate receptors (DCAFs). The DCAF DDB2 detects UV-induced pyrimidine dimers in the genome and facilitates nucleotide excision repair. We provide the molecular basis for DDB2 receptor-mediated cyclobutane pyrimidine dimer recognition in chromatin. The structures of the fully assembled DDB1-DDB2-CUL4A/B-RBX1 (CRL4(DDB2)) ligases reveal that the mobility of the ligase arm creates a defined ubiquitination zone around the damage, which precludes direct ligase activation by DNA lesions. Instead, the COP9 signalosome (CSN) mediates the CRL4(DDB2) inhibition in a CSN5 independent, nonenzymatic, fashion. In turn, CSN inhibition is relieved upon DNA damage binding to the DDB2 module within CSN-CRL4(DDB2). The Cockayne syndrome A DCAF complex crystal structure shows that CRL4(DCAF(WD40)) ligases share common architectural features. Our data support a general mechanism of ligase activation, which is induced by CSN displacement from CRL4(DCAF) on substrate binding to the DCAF. The Molecular Basis of CRL4(DDB2/CSA) Ubiquitin Ligase Architecture, Targeting, and Activation.,Fischer ES, Scrima A, Bohm K, Matsumoto S, Lingaraju GM, Faty M, Yasuda T, Cavadini S, Wakasugi M, Hanaoka F, Iwai S, Gut H, Sugasawa K, Thoma NH Cell. 2011 Nov 23;147(5):1024-39. PMID:22118460[24] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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