title: Crystal structure of a Fanconi anemia-associated nuclease homolog bound to 5' flap DNA: basis of interstrand cross-link repair by FAN1.
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.
authors.affiliation: Department of Life Science, Pohang University of Science and Technology, Pohang 790-784, South Korea;
authors.forename: Gwang Hyeon
authors.initials: GH
authors.lastname: Gwon
authors.affiliation: Department of Life Science, Pohang University of Science and Technology, Pohang 790-784, South Korea;
authors.forename: Youngran
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Department of Life Science, Pohang University of Science and Technology, Pohang 790-784, South Korea;
authors.forename: Yaqi
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, East Sussex BN1 9RQ, United Kingdom;
authors.forename: Adam T
authors.initials: AT
authors.lastname: Watson
authors.affiliation: Department of Life Science, Pohang University of Science and Technology, Pohang 790-784, South Korea;
authors.forename: Aera
authors.initials: A
authors.lastname: Jo
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, East Sussex BN1 9RQ, United Kingdom;
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Etheridge
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, Florida 33136, USA;
authors.forename: Fenghua
authors.initials: F
authors.lastname: Yuan
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, Florida 33136, USA;
authors.forename: Yanbin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Biosciences Division, Structural Biology Center, Argonne National Laboratory, Argonne, Illinois 60439, USA.
authors.forename: YoungChang
authors.initials: Y
authors.lastname: Kim
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, East Sussex BN1 9RQ, United Kingdom;
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Carr
authors.affiliation: Department of Life Science, Pohang University of Science and Technology, Pohang 790-784, South Korea; yunje@postech.ac.kr.
authors.forename: Yunje
authors.initials: Y
authors.lastname: Cho
mesh_terms: D020134:Catalytic Domain; D003460:Crystallization; D005090:Exodeoxyribonucleases / Q000737:chemistry* / Q000378:metabolism; D045585:Flap Endonucleases / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011550:Pseudomonas aeruginosa / Q000737:chemistry* / Q000201:enzymology*
chemical_list: D005090:Exodeoxyribonucleases; D045585:Flap Endonucleases
keywords: Fanconi anemia nuclease 1; crystal structure; interstrand cross-link repair