4noe | pdb_00004noe
Crystal structure of DdrB bound to 30b ssDNA
Structural highlights
FunctionDDRB_DEIRA ssDNA-binding protein that contributes to the ionizing radiation resistance of D.radiodurans. Appears to play a role in DNA repair and genome reconstitution, in a RecA-independent process, and is necessary for recovery from severe genomic fragmentation as a result of exposure to severe levels of ionizing radiation. Binds single-stranded DNA but not duplex DNA.[1] [2] Publication Abstract from PubMedAccurate pairing of DNA strands is essential for repair of DNA double-strand breaks (DSBs). How cells achieve accurate annealing when large regions of single-strand DNA are unpaired has remained unclear despite many efforts focused on understanding proteins, which mediate this process. Here we report the crystal structure of a single-strand annealing protein [DdrB (DNA damage response B)] in complex with a partially annealed DNA intermediate to 2.2 A. This structure and supporting biochemical data reveal a mechanism for accurate annealing involving DdrB-mediated proofreading of strand complementarity. DdrB promotes high-fidelity annealing by constraining specific bases from unauthorized association and only releases annealed duplex when bound strands are fully complementary. To our knowledge, this mechanism provides the first understanding for how cells achieve accurate, protein-assisted strand annealing under biological conditions that would otherwise favor misannealing. Mechanism for accurate, protein-assisted DNA annealing by Deinococcus radiodurans DdrB.,Sugiman-Marangos SN, Weiss YM, Junop MS Proc Natl Acad Sci U S A. 2016 Apr 19;113(16):4308-13. doi:, 10.1073/pnas.1520847113. Epub 2016 Apr 4. PMID:27044084[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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