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.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Animals
-
Binding Sites
-
Chickens
-
Cryoelectron Microscopy
-
Crystallography, X-Ray
-
DNA / chemistry*
-
DNA / genetics
-
DNA / metabolism
-
DNA Damage
-
DNA Repair*
-
Fanconi Anemia Complementation Group D2 Protein / chemistry*
-
Fanconi Anemia Complementation Group D2 Protein / genetics
-
Fanconi Anemia Complementation Group D2 Protein / metabolism
-
Fanconi Anemia Complementation Group Proteins / chemistry*
-
Fanconi Anemia Complementation Group Proteins / genetics
-
Fanconi Anemia Complementation Group Proteins / metabolism
-
Gene Expression
-
Models, Molecular
-
Protein Binding
-
Protein Conformation, alpha-Helical
-
Protein Interaction Domains and Motifs
-
Protein Multimerization
-
Recombinant Proteins / chemistry
-
Recombinant Proteins / genetics
-
Recombinant Proteins / metabolism
-
Sf9 Cells
-
Spodoptera
-
Ubiquitin / chemistry*
-
Ubiquitin / genetics
-
Ubiquitin / metabolism
-
Ubiquitination
Substances
-
Fanconi Anemia Complementation Group D2 Protein
-
Fanconi Anemia Complementation Group Proteins
-
Recombinant Proteins
-
Ubiquitin
-
DNA