Dna2 is a structure-specific nuclease, with affinity for 5'-flap intermediates

• Published in: Nucleic acids research Vol. 38; no. 3; pp. 920 - 930
• Main Authors: Stewart, Jason A, Campbell, Judith L, Bambara, Robert A
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01-01-2010
• Subjects: DNA - chemistry; DNA - metabolism; DNA Helicases - metabolism; DNA, Single-Stranded - metabolism; Endodeoxyribonucleases - metabolism; Nucleic Acid Enzymes; Oligonucleotides - chemistry; Oligonucleotides - metabolism; Substrate Specificity
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/gkp1055

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 ~5 nt. This resembles the mechanism of flap endonuclease 1, consistent with cooperation of these two proteins in flap processing.