PMID: 16622405 , Related PDB ids: 2FBT, 2FBV, 2FBX, 2FBY, 2FC0
Authors:
Perry JJ, Yannone SM, Holden LG, Hitomi C, Asaithamby A, Han S, Cooper PK, Chen DJ, Tainer JA
Title:
WRN exonuclease structure and molecular mechanism imply an editing role in DNA end processing.
Journal:
Nat Struct Mol Biol. 2006 May;13(5):414-22. Epub 2006 Apr 23.
Abstract:
WRN is unique among the five human RecQ DNA helicases in having a functional exonuclease domain (WRN-exo) and being defective in the premature aging and cancer-related disorder Werner syndrome. Here, we characterize WRN-exo crystal structures, biochemical activity and participation in DNA end joining. Metal-ion complex structures, active site mutations and activity assays reveal a nuclease mechanism mediated by two metal ions. The DNA end-binding Ku70/80 complex specifically stimulates WRN-exo activity, and structure-based mutational inactivation of WRN-exo alters DNA end joining in human cells. We furthermore establish structural and biochemical similarities of WRN-exo to DnaQ-family replicative proofreading exonucleases, describing WRN-specific adaptations consistent with double-stranded DNA specificity and functionally important conformational changes. These results indicate WRN-exo is a human DnaQ family member and support DnaQ-like proofreading activities stimulated by Ku70/80, with implications for WRN functions in age-related pathologies and maintenance of genomic integrity.