Note: In the PDB file this reference is
annotated as "TO BE PUBLISHED". The citation details given above have
been manually determined.
Abstract
The Mre11-Rad50-Nbs1 (MRN) complex is a central factor in the repair
ofDNAdouble-strand breaks (DSBs). TheATP-dependent mechanisms of howMRNdetects
and endonucleolytically processesDNAends for the repair by
microhomology-mediated end-joining or further resection in homologous
recombination are still unclear. Here, we report the crystal structures of
theATPγS-bound dimer of the Rad50(NBD)(nucleotide-binding domain) from the
thermophilic eukaryoteChaetomium thermophilum(Ct) in complex with
eitherDNAorCtMre11(RBD)(Rad50-binding domain) along with small-angle X-ray
scattering and cross-linking studies. The structure andDNAbinding motifs were
validated byDNAbinding experimentsin vitroand mutational analyses
inSaccharomyces cerevisiae in vivo Our analyses provide a structural framework
for the architecture of the eukaryotic Mre11-Rad50 complex. They show that a
Rad50 dimer binds approximately 18 base pairs ofDNAalong the dimer interface in
anATP-dependent fashion or bridges two DNAends with a preference for 3'
overhangs. Finally, our results may provide a general framework for the
interaction ofABC ATPase domains of the Rad50/SMC/RecN protein family with DNA.
