The Fanconi Anemia DNA Repair Pathway Is Regulated by an Interaction between Ubiquitin and the E2-like Fold Domain of FANCL.
Bottom Line: The ELF domain is found in all FANCL homologues, yet the function of the domain remains unknown.We show that the interaction is not necessary for the recognition of the core complex, it does not enhance the interaction between FANCL and Ube2T, and is not required for FANCD2 monoubiquitination in vitro.However, we demonstrate that the ELF domain is required to promote efficient DNA damage-induced FANCD2 monoubiquitination in vertebrate cells, suggesting an important function of ubiquitin binding by FANCL in vivo.
Affiliation: From the Protein Structure and Function Laboratory, Lincoln's Inn Fields Laboratories of the London Research Institute, Cancer Research, United Kingdom, 44 Lincoln's Inn Fields, London WC2A 3LY, United Kingdom.Show MeSH
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Mentions: The residues in the ELF domain that are important for ubiquitin binding are not well conserved (Fig. 6A). However, ubiquitin-interacting proteins and motifs such as CUE domains, UBAs, UIMs, and MIUs often share very little sequence homology yet retain functional homology (33). We therefore wanted to determine whether the function of ubiquitin binding is conserved in vertebrate FANCL homologs. We and others had difficulties to make wild type full-length human FANCL, therefore we turned to the Xenopus system. Indeed. Xenopus tropicalis FANCL recapitulates ubiquitin binding (Fig. 6B). Mutation of Asn-72, corresponding to Leu-81 in the Drosophila protein, results in almost a complete loss of interaction with ubiquitin, indicating that the same region in FANCL is required for interaction with ubiquitin (Fig. 6B), and that the interaction is conserved between species.
Affiliation: From the Protein Structure and Function Laboratory, Lincoln's Inn Fields Laboratories of the London Research Institute, Cancer Research, United Kingdom, 44 Lincoln's Inn Fields, London WC2A 3LY, United Kingdom.