ジャーナル: Nature / 年: 2019 タイトル: Structure of the Fanconi anaemia monoubiquitin ligase complex. 著者: Shabih Shakeel / Eeson Rajendra / Pablo Alcón / Francis O'Reilly / Dror S Chorev / Sarah Maslen / Gianluca Degliesposti / Christopher J Russo / Shaoda He / Chris H Hill / J Mark Skehel / ...著者: Shabih Shakeel / Eeson Rajendra / Pablo Alcón / Francis O'Reilly / Dror S Chorev / Sarah Maslen / Gianluca Degliesposti / Christopher J Russo / Shaoda He / Chris H Hill / J Mark Skehel / Sjors H W Scheres / Ketan J Patel / Juri Rappsilber / Carol V Robinson / Lori A Passmore / 要旨: The Fanconi anaemia (FA) pathway repairs DNA damage caused by endogenous and chemotherapy-induced DNA crosslinks, and responds to replication stress. Genetic inactivation of this pathway by mutation ...The Fanconi anaemia (FA) pathway repairs DNA damage caused by endogenous and chemotherapy-induced DNA crosslinks, and responds to replication stress. Genetic inactivation of this pathway by mutation of genes encoding FA complementation group (FANC) proteins impairs development, prevents blood production and promotes cancer. The key molecular step in the FA pathway is the monoubiquitination of a pseudosymmetric heterodimer of FANCD2-FANCI by the FA core complex-a megadalton multiprotein E3 ubiquitin ligase. Monoubiquitinated FANCD2 then recruits additional protein factors to remove the DNA crosslink or to stabilize the stalled replication fork. A molecular structure of the FA core complex would explain how it acts to maintain genome stability. Here we reconstituted an active, recombinant FA core complex, and used cryo-electron microscopy and mass spectrometry to determine its structure. The FA core complex comprises two central dimers of the FANCB and FA-associated protein of 100 kDa (FAAP100) subunits, flanked by two copies of the RING finger subunit, FANCL. These two heterotrimers act as a scaffold to assemble the remaining five subunits, resulting in an extended asymmetric structure. Destabilization of the scaffold would disrupt the entire complex, resulting in a non-functional FA pathway. Thus, the structure provides a mechanistic basis for the low numbers of patients with mutations in FANCB, FANCL and FAAP100. Despite a lack of sequence homology, FANCB and FAAP100 adopt similar structures. The two FANCL subunits are in different conformations at opposite ends of the complex, suggesting that each FANCL has a distinct role. This structural and functional asymmetry of dimeric RING finger domains may be a general feature of E3 ligases. The cryo-electron microscopy structure of the FA core complex provides a foundation for a detailed understanding of its E3 ubiquitin ligase activity and DNA interstrand crosslink repair.
モデルのタイプ: OTHER / 詳細: initial model generated in EMAN2.
最終 再構成
想定した対称性 - 点群: C1 (非対称) / 解像度のタイプ: BY AUTHOR / 解像度: 4.6 Å / 解像度の算出法: FSC 0.143 CUT-OFF / ソフトウェア - 名称: RELION (ver. 3.0) 詳細: Local symmetry was applied for two regions followed by autorefinement was was done with tau_fudge (T)=100. Map was post processed to obtain realistic resolution for the map. 使用した粒子像数: 49423
初期 角度割当
タイプ: MAXIMUM LIKELIHOOD / ソフトウェア - 名称: RELION (ver. 3.0)
最終 角度割当
タイプ: MAXIMUM LIKELIHOOD / ソフトウェア - 名称: RELION (ver. 3.0)
FSC曲線 (解像度の算出)
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原子モデル構築 1
精密化
プロトコル: OTHER
得られたモデル
PDB-6srs: Structure of the Fanconi anaemia core subcomplex