Structure of the DNA Repair and Replication Endonuclease and Exonuclease FEN-1: Coupling DNA and PCNA Binding to FEN-1 Activity

• Published in: Cell 1998-10, Vol.95 (1), p.135-146
• Main Authors: Hosfield, David J, Mol, Clifford D, Shen, Binghui, Tainer, John A
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Binding Sites; Catalysis; DNA - metabolism; DNA Repair; DNA Replication; Endodeoxyribonucleases - chemistry; Endodeoxyribonucleases - metabolism; Endonucleases - chemistry; Endonucleases - metabolism; Exodeoxyribonuclease V; Exodeoxyribonucleases - chemistry; Exonucleases - chemistry; Exonucleases - metabolism; Flap Endonucleases; Ions; Magnesium; Molecular Sequence Data; Proliferating Cell Nuclear Antigen - metabolism; Protein Conformation; Pyrococcus furiosus; Pyrococcus furiosus - enzymology
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/S0092-8674(00)81789-4

Flap endonuclease (FEN-1) removes 5′ overhanging flaps in DNA repair and processes the 5′ ends of Okazaki fragments in lagging strand DNA synthesis. The crystal structure of Pyrococcus furiosus FEN-1, active-site metal ions, and mutational information indicate interactions for the single- and double-stranded portions of the flap DNA substrate and identify an unusual DNA-binding motif. The enzyme’s active-site structure suggests that DNA binding induces FEN-1 to clamp onto the cleavage junction to form the productive complex. The conserved FEN-1 C terminus binds proliferating cell nuclear antigen (PCNA) and positions FEN-1 to act primarily as an exonuclease in DNA replication, in contrast to its endonuclease activity in DNA repair. FEN-1 mutations altering PCNA binding should reduce activity during replication, likely causing DNA repeat expansions as seen in some cancers and genetic diseases.