The Fanconi Anemia (FA) DNA repair pathway is essential for the recognition and repair of DNA interstrand crosslinks (ICL). Inefficient repair of these ICL can lead to leukaemia and bone marrow failure. The vital step of the pathway is the monoubiquitination of FANCD2 and FANCI by the RING E3 ligase FANCL, part of a core complex of proteins. This process requires the co-ordination of 3 proteins, the E1 activating enzyme, E2-conjugating (Ube2T) and E3 ligase (FANCL). Once FANCD2 and FANCI are modified with ubiquitin, they co-localise on the chromatin at the site of damage with other repair factors such as BRCA2, and the ICL is removed. A further DNA repair process, translesion synthesis (TLS), works alongside the FA pathway. The key step in TLS is the monoubiquitination of PCNA by the E2/E3 pairing of Ube2B(Rad6) and Rad18. However, the molecular and mechanistic details of how these two DNA repair pathways converge are poorly understood. The data presented will demonstrate that the E2-like fold (ELF) domain within FANCL is able to interact non-covalently with ubiquitin. This interaction is not necessary for the recognition of ubiquitin on the Ube2T or on FANCL itself, and is not required for catalysis in vitro. Mutation of the interaction in cells lead to a loss of FANCD2 monoubiquitination, but this is not due to a loss of core complex formation. Finally I show that the interaction between the ELF domain and ubiquitin may mediate the enhancement of FANCD2 monoubiquitination seen by the inclusion of monoubiquitinated PCNA. The observations provide critical mechanistic insights into the processes involved in monoubiquitination and the molecular basis for the observed link between TLS and activation of the FA pathway.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:626773 |
| Date | January 2014 |
| Creators | Miles, J. A. |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/1418872/ |
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