skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: WRN Exonuclease Structure, Molecular Mechanism, and DNA EndProcessing Role

Abstract

WRN is unique among the five human RecQ DNA helicases by 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 two-metal-ion mediated nuclease mechanism. 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, with WRN-specific adaptations consistent with dsDNA specificity and functionally important conformational changes. These results indicate WRN-exo is a human DnaQ family member and support analogous proof-reading activities that are stimulated by Ku70/80 with implications for WRN functions in age related pathologies and maintenance of genomic integrity.

Authors:
; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE Director, Office of Science. Office of Biological andEnvironmental Research. Life Sciences Division
OSTI Identifier:
891194
Report Number(s):
LBNL-53236
R&D Project: L0423; BnR: 600303000; TRN: US200621%%657
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature Structural and Molecular Biology; Journal Volume: 13; Related Information: Journal Publication Date: 2006
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 60 APPLIED LIFE SCIENCES; AGING; ANIMAL CELLS; BIOCHEMISTRY; CONFORMATIONAL CHANGES; CRYSTAL STRUCTURE; DNA; DNA HELICASES; FUNCTIONALS; INACTIVATION; MAINTENANCE; MUTATIONS; NUCLEASES; PROCESSING; SPECIFICITY

Citation Formats

Perry, J. Jefferson P., Yannone, Steven M., Holden, Lauren G., Hitomi, Chiharu, Asaithamby, Aroumougame, Han, Seungil, Cooper, PriscillaK., Chen, David J., and Tainer, John A. WRN Exonuclease Structure, Molecular Mechanism, and DNA EndProcessing Role. United States: N. p., 2006. Web. doi:10.1038/nsmb1088.
Perry, J. Jefferson P., Yannone, Steven M., Holden, Lauren G., Hitomi, Chiharu, Asaithamby, Aroumougame, Han, Seungil, Cooper, PriscillaK., Chen, David J., & Tainer, John A. WRN Exonuclease Structure, Molecular Mechanism, and DNA EndProcessing Role. United States. doi:10.1038/nsmb1088.
Perry, J. Jefferson P., Yannone, Steven M., Holden, Lauren G., Hitomi, Chiharu, Asaithamby, Aroumougame, Han, Seungil, Cooper, PriscillaK., Chen, David J., and Tainer, John A. Wed . "WRN Exonuclease Structure, Molecular Mechanism, and DNA EndProcessing Role". United States. doi:10.1038/nsmb1088. https://www.osti.gov/servlets/purl/891194.
@article{osti_891194,
title = {WRN Exonuclease Structure, Molecular Mechanism, and DNA EndProcessing Role},
author = {Perry, J. Jefferson P. and Yannone, Steven M. and Holden, Lauren G. and Hitomi, Chiharu and Asaithamby, Aroumougame and Han, Seungil and Cooper, PriscillaK. and Chen, David J. and Tainer, John A.},
abstractNote = {WRN is unique among the five human RecQ DNA helicases by 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 two-metal-ion mediated nuclease mechanism. 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, with WRN-specific adaptations consistent with dsDNA specificity and functionally important conformational changes. These results indicate WRN-exo is a human DnaQ family member and support analogous proof-reading activities that are stimulated by Ku70/80 with implications for WRN functions in age related pathologies and maintenance of genomic integrity.},
doi = {10.1038/nsmb1088},
journal = {Nature Structural and Molecular Biology},
number = ,
volume = 13,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2006},
month = {Wed Feb 15 00:00:00 EST 2006}
}
  • Highlights: {yields} In this study, we investigated the effect of a DNA secondary structure on the two WRN activities. {yields} We found that a DNA secondary structure of the displaced strand during unwinding stimulates WRN helicase without coordinate action of WRN exonuclease. {yields} These results imply that WRN helicase and exonuclease activities can act independently. -- Abstract: Werner syndrome (WS) is an autosomal recessive premature aging disorder characterized by aging-related phenotypes and genomic instability. WS is caused by mutations in a gene encoding a nuclear protein, Werner syndrome protein (WRN), a member of the RecQ helicase family, that interestingly possessesmore » both helicase and exonuclease activities. Previous studies have shown that the two activities act in concert on a single substrate. We investigated the effect of a DNA secondary structure on the two WRN activities and found that a DNA secondary structure of the displaced strand during unwinding stimulates WRN helicase without coordinate action of WRN exonuclease. These results imply that WRN helicase and exonuclease activities can act independently, and we propose that the uncoordinated action may be relevant to the in vivo activity of WRN.« less
  • No abstract prepared.
  • WRN, the protein defective in Werner syndrome (WS), is a multifunctional nuclease involved in DNA damage repair, replication, and genome stability maintenance. It was assumed that the nuclease activities of WRN were critical for these functions. Here, we report a nonenzymatic role for WRN in preserving nascent DNA strands following replication stress. We found that lack of WRN led to shortening of nascent DNA strands after replication stress. Furthermore, we discovered that the exonuclease activity of MRE11 was responsible for the shortening of newly replicated DNA in the absence of WRN. Mechanistically, the N-terminal FHA domain of NBS1 recruits WRNmore » to replication-associated DNA double-stranded breaks to stabilize Rad51 and to limit the nuclease activity of its C-terminal binding partner MRE11. Thus, this previously unrecognized nonenzymatic function of WRN in the stabilization of nascent DNA strands sheds light on the molecular reason for the origin of genome instability in WS individuals.« less
  • No abstract prepared.
  • No abstract prepared.