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FANCD2-FANCI is a clamp stabilized on DNA by monoubiquitination of FANCD2 during DNA repair.
Nature Structural & Molecular Biology ( IF 12.5 ) Pub Date : 2020-02-17 , DOI: 10.1038/s41594-020-0380-1
Pablo Alcón 1 , Shabih Shakeel 1 , Zhuo A Chen 2 , Juri Rappsilber 2, 3 , Ketan J Patel 1 , Lori A Passmore 1
Affiliation  

Vertebrate DNA crosslink repair excises toxic replication-blocking DNA crosslinks. Numerous factors involved in crosslink repair have been identified, and mutations in their corresponding genes cause Fanconi anemia (FA). A key step in crosslink repair is monoubiquitination of the FANCD2-FANCI heterodimer, which then recruits nucleases to remove the DNA lesion. Here, we use cryo-EM to determine the structures of recombinant chicken FANCD2 and FANCI complexes. FANCD2-FANCI adopts a closed conformation when the FANCD2 subunit is monoubiquitinated, creating a channel that encloses double-stranded DNA (dsDNA). Ubiquitin is positioned at the interface of FANCD2 and FANCI, where it acts as a covalent molecular pin to trap the complex on DNA. In contrast, isolated FANCD2 is a homodimer that is unable to bind DNA, suggestive of an autoinhibitory mechanism that prevents premature activation. Together, our work suggests that FANCD2-FANCI is a clamp that is locked onto DNA by ubiquitin, with distinct interfaces that may recruit other DNA repair factors.

中文翻译:


FANCD2-FANCI 是一种在 DNA 修复过程中通过 FANCD2 单泛素化稳定在 DNA 上的钳子。



脊椎动物 DNA 交联修复切除了有毒的复制阻断 DNA 交联。已经确定了许多参与交联修复的因素,其相应基因的突变会导致范可尼贫血(FA)。交联修复的一个关键步骤是 FANCD2-FANCI 异二聚体的单泛素化,然后招募核酸酶来去除 DNA 损伤。在这里,我们使用冷冻电镜来确定重组鸡 FANCD2 和 FANCI 复合物的结构。当 FANCD2 亚基单泛素化时,FANCD2-FANCI 采用闭合构象,形成包围双链 DNA (dsDNA) 的通道。泛素位于 FANCD2 和 FANCI 的界面处,充当共价分子销,将复合物捕获在 DNA 上。相比之下,分离的 FANCD2 是一种同二聚体,无法结合 DNA,这表明存在防止过早激活的自动抑制机制。总之,我们的工作表明 FANCD2-FANCI 是一种通过泛素锁定在 DNA 上的钳子,具有可能招募其他 DNA 修复因子的独特界面。
更新日期:2020-02-17
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