title: A novel mode of nuclease action is revealed by the bacterial Mre11/Rad50 complex.
abstract: The Mre11/Rad50 complex is a central player in various genome maintenance pathways. Here, we report a novel mode of nuclease action found for the Escherichia coli Mre11/Rad50 complex, SbcC2/D2 complex (SbcCD). SbcCD cuts off the top of a cruciform DNA by making incisions on both strands and continues cleaving the dsDNA stem at ∼10-bp intervals. Using linear-shaped DNA substrates, we observed that SbcCD cleaved dsDNA using this activity when the substrate was 110 bp long, but that on shorter substrates the cutting pattern was changed to that predicted for the activity of a 3'-5' exonuclease. Our results suggest that SbcCD processes hairpin and linear dsDNA ends with this novel DNA end-dependent binary endonuclease activity in response to substrate length rather than using previously reported activities. We propose a model for this mode of nuclease action, which provides new insight into SbcCD activity at a dsDNA end.
authors: Division of Systems Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan.
authors: Chew Theng
authors: CT
authors: Lim
authors: Division of Systems Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan.
authors: Pey Jiun
authors: PJ
authors: Lai
authors: Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Kings Buildings, Edinburgh EH9 3JR, UK.
authors: David R F
authors: DR
authors: Leach
authors: Division of Systems Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan.
authors: Hisaji
authors: H
authors: Maki
authors: Division of Systems Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan furukori@bs.naist.jp.
authors: Asako
authors: A
authors: Furukohri
mesh_terms: D004247:DNA / Q000737:chemistry / Q000378:metabolism; D053837:DNA Cleavage; D045566:DNA, Cruciform / Q000378:metabolism*; D003851:Deoxyribonucleases / Q000378:metabolism*; D004706:Endodeoxyribonucleases / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D005092:Exonucleases / Q000378:metabolism*
chemical_list: D045566:DNA, Cruciform; D029968:Escherichia coli Proteins; C489229:SbcC protein, E coli; D004247:DNA; D003851:Deoxyribonucleases; D004706:Endodeoxyribonucleases; D005092:Exonucleases; C081229:sbcD protein, E coli