FANCD2–FANCI is a clamp stabilized on DNA by monoubiquitination of FANCD2 during DNA repair

DOI: 10.1038/s41594-020-0380-1

Authors: Pablo Alcon (MRC Laboratory of Molecular Biology) , Shabih Shakeel (MRC Laboratory of Molecular Biology) , Zhuo A. Chen (Technische Universität Berlin) , Juri Rappsilber (Technische Universität Berlin) , Ketan J. Patel (MRC Laboratory of Molecular Biology) , Lori Passmore (MRC Laboratory of Molecular Biology)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nature Structural & Molecular Biology , VOL 493

State: Published (Approved)
Published: February 2020
Diamond Proposal Number(s): 17434 , 23268

Abstract: 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.

Journal Keywords: Cryoelectron microscopy; DNA damage and repair

Subject Areas: Biology and Bio-materials

Diamond Offline Facilities: Electron Bio-Imaging Centre (eBIC)
Instruments: Krios I-Titan Krios I at Diamond