title: Dna2 is a structure-specific nuclease, with affinity for 5'-flap intermediates.
abstract: Dna2 is a nuclease/helicase with proposed roles in DNA replication, double-strand break repair and telomere maintenance. For each role Dna2 is proposed to process DNA substrates with a 5'-flap. To date, however, Dna2 has not revealed a preference for binding or cleavage of flaps over single-stranded DNA. Using DNA binding competition assays we found that Dna2 has substrate structure specificity. The nuclease displayed a strong preference for binding substrates with a 5'-flap or some variations of flap structure. Further analysis revealed that Dna2 recognized and bound both the single-stranded flap and portions of the duplex region immediately downstream of the flap. A model is proposed in which Dna2 first binds to a flap base, and then the flap threads through the protein with periodic cleavage, to a terminal flap length of approximately 5 nt. This resembles the mechanism of flap endonuclease 1, consistent with cooperation of these two proteins in flap processing.
authors.affiliation: Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors.forename: Jason A
authors.initials: JA
authors.lastname: Stewart
authors.forename: Judith L
authors.initials: JL
authors.lastname: Campbell
authors.forename: Robert A
authors.initials: RA
authors.lastname: Bambara
mesh_terms: D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004265:DNA Helicases / Q000378:metabolism*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004706:Endodeoxyribonucleases / Q000378:metabolism*; D009841:Oligonucleotides / Q000737:chemistry / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D004277:DNA, Single-Stranded; D009841:Oligonucleotides; D004247:DNA; D004706:Endodeoxyribonucleases; D004265:DNA Helicases