title: Structural basis for role of ring finger protein RNF168 RING domain.
abstract: Ubiquitin adducts surrounding DNA double-strand breaks (DSBs) have emerged as molecular platforms important for the assembly of DNA damage mediator and repair proteins. Central to these chromatin modifications lies the E2 UBC13, which has been implicated in a bipartite role in priming and amplifying lys63-linked ubiquitin chains on histone molecules through coupling with the E3 RNF8 and RNF168. However, unlike the RNF8-UBC13 holoenyzme, exactly how RNF168 work in concert with UBC13 remains obscure. To provide a structural perspective for the RNF168-UBC13 complex, we solved the crystal structure of the RNF168 RING domain. Interestingly, while the RNF168 RING adopts a typical RING finger fold with two zinc ions coordinated by several conserved cystine and histine residues arranged in a C3HC4 "cross-brace" manner, structural superimposition of RNF168 RING with other UBC13-binding E3 ubiquitin ligases revealed substantial differences at its corresponding UBC13-binding interface. Consistently, and in stark contrast to that between RNF8 and UBC13, RNF168 did not stably associate with UBC13 in vitro or in vivo. Moreover, domain-swapping experiments indicated that the RNF8 and RNF168 RING domains are not functionally interchangeable. We propose that RNF8 and RNF168 operate in different modes with their cognate E2 UBC13 at DSBs.
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, People's Republic of China.
authors.forename: Xiaoqin
authors.initials: X
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.forename: Minhao
authors.initials: M
authors.lastname: Wu
authors.forename: Huakai
authors.initials: H
authors.lastname: Wu
authors.forename: Aloysius Wilfred
authors.initials: AW
authors.lastname: Arokiaraj
authors.forename: Chengliang
authors.initials: C
authors.lastname: Wang
authors.forename: Weichang
authors.initials: W
authors.lastname: Zhang
authors.forename: Yue
authors.initials: Y
authors.lastname: Tao
authors.forename: Michael S Y
authors.initials: MS
authors.lastname: Huen
authors.forename: Jianye
authors.initials: J
authors.lastname: Zang
mesh_terms: D003001:Cloning, Molecular; D003460:Crystallization; D053903:DNA Breaks, Double-Stranded; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D011487:Protein Conformation; D054829:RING Finger Domains / Q000235:genetics*; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; C486521:RNF8 protein, human; C471607:UBE2N protein, human; D044763:Ubiquitin-Conjugating Enzymes; C535210:RNF168 protein, human; D044767:Ubiquitin-Protein Ligases