Visualization of local DNA unwinding by Mre11/Rad50/Nbs1 using single-molecule FRET.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 24191051.
- Also identified by DOI 10.1073/pnas.1309816110 and PMC identifier 3839711.
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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.
Medical subject headings
- DNA Breaks, Double-Stranded
- DNA Helicases
- DNA Repair
- Fluorescence Resonance Energy Transfer
- Multiprotein Complexes