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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.

SUBMITTER: Cannon B

PROVIDER: S-EPMC3839711 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature

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Visualization of local DNA unwinding by Mre11/Rad50/Nbs1 using single-molecule FRET.

Cannon Brian B Kuhnlein Jeffrey J Yang Soo-Hyun SH Cheng Anita A Schindler Detlev D Stark Jeremy M JM Russell Rick R Paull Tanya T TT

Proceedings of the National Academy of Sciences of the United States of America 20131104 47

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-depe ...[more]

PMID: 24191051

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Single-Molecule Imaging Reveals How Mre11-Rad50-Nbs1 Initiates DNA Break Repair.

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