Monoubiquitination by the human Fanconi anemia core complex clamps FANCI:FANCD2 on DNA in filamentous arrays.

Winnie Tan, Sylvie van Twest, Andrew Leis, Rohan Bythell-Douglas, Vincent J Murphy, Michael Sharp, Michael W Parker, Wayne Crismani, Andrew J Deans

eLife 2020 Mar 13

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FANCI:FANCD2 monoubiquitination is a critical event for replication fork stabilization by the Fanconi anemia (FA) DNA repair pathway. It has been proposed that at stalled replication forks, monoubiquitinated-FANCD2 serves to recruit DNA repair proteins that contain ubiquitin-binding motifs. Here, we have reconstituted the FA pathway in vitro to study functional consequences of FANCI:FANCD2 monoubiquitination. We report that monoubiquitination does not promote any specific exogenous protein:protein interactions, but instead stabilizes FANCI:FANCD2 heterodimers on dsDNA. This clamping requires monoubiquitination of only the FANCD2 subunit. We further show using electron microscopy that purified monoubiquitinated FANCI:FANCD2 forms filament-like arrays on long dsDNA. Our results reveal how monoubiquitinated FANCI:FANCD2, defective in many cancer types and all cases of FA, is activated upon DNA binding. © 2020, Tan et al.

Citation

Winnie Tan, Sylvie van Twest, Andrew Leis, Rohan Bythell-Douglas, Vincent J Murphy, Michael Sharp, Michael W Parker, Wayne Crismani, Andrew J Deans. Monoubiquitination by the human Fanconi anemia core complex clamps FANCI:FANCD2 on DNA in filamentous arrays. eLife. 2020 Mar 13;9