The N-terminal 45-kDa Domain of Dna2 Endonuclease/Helicase Targets the Enzyme to Secondary Structure DNA |
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Authors: | Chul-Hwan Lee Miju Lee Hyo-Jin Kang Do-Hyung Kim Young-Hoon Kang Sung-Ho Bae Yeon-Soo Seo |
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Institution: | From the ‡Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, 305-701 and ;the §Department of Biological Sciences, Inha University, Incheon, 402-751, Korea |
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Abstract: | The removal of initiating primers from the 5′-ends of each Okazaki fragment, required for the generation of contiguous daughter strands, can be catalyzed by the combined action of DNA polymerase δ and Fen1. When the flaps generated by displacement of DNA synthesis activity of polymerase δ become long enough to bind replication protein A or form hairpin structures, the helicase/endonuclease enzyme, Dna2, becomes critical because of its ability to remove replication protein A-coated or secondary structure flaps. In this study, we show that the N-terminal 45-kDa domain of Dna2 binds hairpin structures, allowing the enzyme to target secondary structure flap DNA. We found that this activity was essential for the efficient removal of hairpin flaps by the endonuclease activity of Dna2 with the aid of its helicase activity. Thus, the efficient removal of hairpin structure flaps requires the coordinated action of all three functional domains of Dna2. We also found that deletion of the N-terminal 45-kDa domain of Dna2 led to a partial loss of the intra-S-phase checkpoint function and an increased rate of homologous recombination in yeast. We discuss the potential roles of the N-terminal domain of Dna2 in the maintenance of genomic stability. |
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Keywords: | DNA Damage DNA Enzymes DNA Helicase DNA Replication Enzyme Structure Dna2 Endonuclease Okazaki Fragment Processing Double Strand Break Genome Stability Resection |
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