title: Visualization of local DNA unwinding by Mre11/Rad50/Nbs1 using single-molecule FRET.
abstract: The Mre11/Rad50/Nbs1 (MRN) complex initiates and coordinates DNA repair and signaling events at double-strand breaks. The interaction between MRN and DNA ends is critical for the recruitment of DNA-processing enzymes, end tethering, and activation of the ATM protein kinase. Here we visualized MRN binding to duplex DNA molecules using single-molecule FRET, and found that MRN unwinds 15-20 base pairs at the end of the duplex, holding the branched structure open for minutes at a time in an ATP-dependent reaction. A Rad50 catalytic domain mutant that is specifically deficient in this ATP-dependent opening is impaired in DNA end resection in vitro and in resection-dependent repair of breaks in human cells, demonstrating the importance of MRN-generated single strands in the repair of DNA breaks.
authors.affiliation: Department of Chemistry and Biochemistry, Department of Molecular Genetics and Microbiology, Institute for Cellular and Molecular Biology, and Howard Hughes Medical Institute, University of Texas, Austin, TX 78712.
authors.forename: Brian
authors.initials: B
authors.lastname: Cannon
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Kuhnlein
authors.forename: Soo-Hyun
authors.initials: SH
authors.lastname: Yang
authors.forename: Anita
authors.initials: A
authors.lastname: Cheng
authors.forename: Detlev
authors.initials: D
authors.lastname: Schindler
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Stark
authors.forename: Rick
authors.initials: R
authors.lastname: Russell
authors.forename: Tanya T
authors.initials: TT
authors.lastname: Paull
mesh_terms: D017766:Acid Anhydride Hydrolases; D018797:Cell Cycle Proteins / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D004265:DNA Helicases / Q000378:metabolism*; D004260:DNA Repair / Q000235:genetics / Q000502:physiology*; D045643:DNA Repair Enzymes / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D006801:Humans; D000076228:MRE11 Homologue Protein; D046912:Multiprotein Complexes / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C121766:MRE11 protein, human; D046912:Multiprotein Complexes; C112156:NBN protein, human; D009687:Nuclear Proteins; D000076228:MRE11 Homologue Protein; D017766:Acid Anhydride Hydrolases; C112158:RAD50 protein, human; D004265:DNA Helicases; D045643:DNA Repair Enzymes
keywords: DNA structure; DNA–protein interaction