Identification of the FANCI protein, a monoUbiquitinated FANCD2 paralog required for DNA repair

Department of Genetics, Howard Hughes Medical Institute, Center for Genetics and Genomics, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
Cell (Impact Factor: 33.12). 05/2007; 129(2):289-301. DOI: 10.1016/j.cell.2007.03.009
Source: PubMed

ABSTRACT Fanconi anemia (FA) is a developmental and cancer-predisposition syndrome caused by mutations in genes controlling DNA interstrand crosslink repair. Several FA proteins form a ubiquitin ligase that controls monoubiquitination of the FANCD2 protein in an ATR-dependent manner. Here we describe the FA protein FANCI, identified as an ATM/ATR kinase substrate required for resistance to mitomycin C. FANCI shares sequence similarity with FANCD2, likely evolving from a common ancestral gene. The FANCI protein associates with FANCD2 and, together, as the FANCI-FANCD2 (ID) complex, localize to chromatin in response to DNA damage. Like FANCD2, FANCI is monoubiquitinated and unexpectedly, ubiquitination of each protein is important for the maintenance of ubiquitin on the other, indicating the existence of a dual ubiquitin-locking mechanism required for ID complex function. Mutation in FANCI is responsible for loss of a functional FA pathway in a patient with Fanconi anemia complementation group I.

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Available from: Agata Smogorzewska, Mar 16, 2015
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    • "Please cite this article in press as: Rickman et al., Deficiency of UBE2T, the E2 Ubiquitin Ligase Necessary for FANCD2 and FANCI Ubiquitination, Causes FA-T Subtype of Fanconi Anemia, Cell Reports (2015), described to interact with FANCL and ubiquitinate FANCD2 in vitro, but the physiological importance of this interaction has not been explored in mammalian cells (Alpi et al., 2008; Rajendra et al., 2014; Zhang et al., 2011). Activated FANCD2 and FANCI form the ID2 complex that localizes to chromatin and is required for coordinating repair at the crosslink (Garcia-Higuera et al., 2001; Knipscheer et al., 2009; Smogorzewska et al., 2007). Processing of the ICL encompasses nucleolytic unhooking of the crosslink that is dependent on FANCP/SLX4 and ERCC4/FANCQ/XPF, translesion synthesis bypass of the unhooked ICL on one strand, and double-strand break (DSB) repair by homologous recombination (HR) on the other strand (Kim et al., 2011, 2013; Klein Douwel et al., 2014; Long et al., 2011; Niedernhofer et al., 2004; Tischkowitz et al., 2007; Xia et al., 2007). "
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    ABSTRACT: Fanconi anemia (FA) is a rare bone marrow failure and cancer predisposition syndrome resulting from pathogenic mutations in genes encoding proteins participating in the repair of DNA interstrand crosslinks (ICLs). Mutations in 17 genes (FANCA-FANCS) have been identified in FA patients, defining 17 complementation groups. Here, we describe an individual presenting with typical FA features who is deficient for the ubiquitin-conjugating enzyme (E2), UBE2T. UBE2T is known to interact with FANCL, the E3 ubiquitin-ligase component of the multiprotein FA core complex, and is necessary for the monoubiquitination of FANCD2 and FANCI. Proband fibroblasts do not display FANCD2 and FANCI monoubiquitination, do not form FANCD2 foci following treatment with mitomycin C, and are hypersensitive to crosslinking agents. These cellular defects are complemented by expression of wild-type UBE2T, demonstrating that deficiency of the protein UBE2T can lead to Fanconi anemia. UBE2T gene gains an alias of FANCT. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.
    Cell Reports 06/2015; 12(1). DOI:10.1016/j.celrep.2015.06.014 · 8.36 Impact Factor
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    • "The FANCM– FAAP24 complex activates the ataxia telangiectasia and Rad3-related (ATR) signaling pathway and recruits the FA core complex, which is composed of multiple subunits (A, B, C, E, F, G, L, and M) (Garcia-Higuera et al. 2001; Pichierri and Rosselli 2004; Ciccia et al. 2007; Ling et al. 2007; Smogorzewska et al. 2007; Collis et al. 2008; Schwab et al. 2010). Another important event is the monoubiquitination of FANCD2 by FANCL, the E3 ligase subunit of the FA core (Moldovan and D'Andrea 2009; Smogorzewska et al. 2007; Knipscheer et al. 2009; Thompson and Hinz 2009). Monoubiquitinated FANCD2 then acts as a landing pad for recruiting ubiquitin-binding zinc (UBZ) domain-containing proteins, such as FA-associated nuclease 1 (FAN1) and SLX4, to the lesion via its monoubiquitin group (Kratz et al. 2010; Liu et al. 2010; MacKay et al. 2010; Smogorzewska et al. 2010). "
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    ABSTRACT: Fanconi anemia (FA) is an autosomal recessive genetic disorder caused by defects in any of 15 FA genes responsible for processing DNA interstrand cross-links (ICLs). The ultimate outcome of the FA pathway is resolution of cross-links, which requires structure-selective nucleases. FA-associated nuclease 1 (FAN1) is believed to be recruited to lesions by a monoubiquitinated FANCI–FANCD2 (ID) complex and participates in ICL repair. Here, we determined the crystal structure of Pseudomonas aeruginosa FAN1 (PaFAN1) lacking the UBZ (ubiquitin-binding zinc) domain in complex with 5′ flap DNA. All four domains of the right-hand-shaped PaFAN1 are involved in DNA recognition, with each domain playing a specific role in bending DNA at the nick. The six-helix bundle that binds the junction connects to the catalytic viral replication and repair (VRR) nuclease (VRR nuc) domain, enabling FAN1 to incise the scissile phosphate a few bases distant from the junction. The six-helix bundle also inhibits the cleavage of intact Holliday junctions. PaFAN1 shares several conserved features with other flap structure-selective nucleases despite structural differences. A clamping motion of the domains around the wedge helix, which acts as a pivot, facilitates nucleolytic cleavage. The PaFAN1 structure provides insights into how archaeal Holliday junction resolvases evolved to incise 5′ flap substrates and how FAN1 integrates with the FA complex to participate in ICL repair.
    Genes & development 09/2014; 28(28):2276-2290. DOI:10.1101/gad.248492.114 · 12.64 Impact Factor
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    • "FANCI monoubiquitination is presumed to be catalyzed by the FA core complex, but this modification is dispensable for DNA repair (Ishiai et al., 2008; Sims et al., 2007; Smogorzewska et al., 2007). We only observed weak FANCI monoubiquitination in our assay that was not affected by the presence of FANCD2 or DNA and did not significantly increase over time, suggesting that it may not be physiologically relevant (HA blots in Figures 3B, S1D, and S2). "
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    ABSTRACT: Fanconi anaemia (FA) is a cancer predisposition syndrome characterized by cellular sensitivity to DNA interstrand crosslinkers. The molecular defect in FA is an impaired DNA repair pathway. The critical event in activating this pathway is monoubiquitination of FANCD2. In vivo, a multisubunit FA core complex catalyzes this step, but its mechanism is unclear. Here, we report purification of a native avian FA core complex and biochemical reconstitution of FANCD2 monoubiquitination. This demonstrates that the catalytic FANCL E3 ligase subunit must be embedded within the complex for maximal activity and site specificity. We genetically and biochemically define a minimal subcomplex comprising just three proteins (FANCB, FANCL, and FAAP100) that functions as the monoubiquitination module. Residual FANCD2 monoubiquitination activity is retained in cells defective for other FA core complex subunits. This work describes the in vitro reconstitution and characterization of this multisubunit monoubiquitin E3 ligase, providing key insight into the conserved FA DNA repair pathway.
    Molecular Cell 06/2014; 54(5):858-869. DOI:10.1016/j.molcel.2014.05.001 · 14.46 Impact Factor
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