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bioRxiv · 10.1101/862805

Monoubiquitination by the Fanconi Anemia core complex locks FANCI:FANCD2 on DNA in filamentous arrays

Tan, W.·van Twest, S.·Leis, A.·Bythell-Douglas, R.·Murphy, V. J.·Sharp, M.·Parker, M. W.·Crismani, W. M.·Deans, A. J.
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Abstract

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 locking of FANCI:FANCD2 complex on DNA requires monoubiquitination of only the FANCD2 subunit. We further show that purified monoubiquitinated FANCI:FANCD2 forms filament-like arrays on long dsDNA using electron microscopy. Our results reveal how monoubiquitinated FANCI:FANCD2 is activated upon DNA binding and present new insights to potentially modulate monoubiquitinated FANCI:FANCD2/DNA filaments in FA cells.

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Tan, W., van Twest, S., Leis, A., Bythell-Douglas, R., Murphy, V. J., Sharp, M., Parker, M. W., Crismani, W. M., Deans, A. J.. 2019-12-03. Monoubiquitination by the Fanconi Anemia core complex locks FANCI:FANCD2 on DNA in filamentous arrays. https://doi.org/10.1101/862805

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