TY - JOUR
T1 - WRN exonuclease structure and molecular mechanism imply an editing role in DNA end processing
AU - Perry, J. Jefferson P.
AU - Yannone, Steven M.
AU - Holden, Lauren G.
AU - Hitomi, Chiharu
AU - Asaithamby, Aroumougame
AU - Han, Seungil
AU - Cooper, Priscilla K.
AU - Chen, David J.
AU - Tainer, John A.
N1 - Funding Information:
We thank J. Campisi and S. Huang (Berkeley Lab) for the full-length WRN clone and WRN cell lines used in the microhomology repair assay, D. King for MS/MS analysis of proteolytic digests and D. McRee and Syrrx Inc. for use of the Syrrx Inc. robotic crystallization screens to discover initial WRN-exo crystallization conditions. We thank S. Williams and J. Tubbs for critical reading of the manuscript. This work was supported by US National Institutes of Health grants CA104660 (J.A.T., S.M.Y.), CA63503 (P.K.C.) and CA92584 (J.A.T., P.K.C., D.J.C.).
PY - 2006/5/14
Y1 - 2006/5/14
N2 - 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.
AB - 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.
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U2 - 10.1038/nsmb1088
DO - 10.1038/nsmb1088
M3 - Article
C2 - 16622405
AN - SCOPUS:33745084835
SN - 1545-9993
VL - 13
SP - 414
EP - 422
JO - Nature Structural and Molecular Biology
JF - Nature Structural and Molecular Biology
IS - 5
ER -