Abstract |
Werner syndrome (WS) is a rare progeroid disorder characterized by genomic instability, increased cancer incidence, and early onset of a variety of aging pathologies. WS is unique among early aging syndromes in that affected individuals are developmentally normal, and phenotypic onset is in early adulthood. The protein defective in WS (WRN) is a member of the large RecQ family of helicases but is unique among this family in having an exonuclease. RecQ helicases form multimers, but the mechanism and consequence of multimerization remain incompletely defined. Here, we identify a novel heptad repeat coiled coil region between the WRN nuclease and helicase domains that facilitates multimerization of WRN. We mapped a novel and unique DNA-dependent protein kinase phosphorylation site proximal to the WRN multimerization region. However, phosphorylation at this site affected neither exonuclease activity nor multimeric state. We found that WRN nuclease is stimulated by DNA-dependent protein kinase independently of kinase activity or WRN nuclease multimeric status. In addition, WRN nuclease multimerization significantly increased nuclease processivity. We found that the novel WRN coiled coil domain is necessary for multimerization of the nuclease domain and sufficient to multimerize with full-length WRN in human cells. Importantly, correct homomultimerization is required for WRN function in vivo as overexpression of this multimerization domain caused increased sensitivity to camptothecin and 4-nitroquinoline 1-oxide similar to that in cells lacking functional WRN protein.
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Authors | J Jefferson P Perry, Aroumougame Asaithamby, Adam Barnebey, Foad Kiamanesch, David J Chen, Seungil Han, John A Tainer, Steven M Yannone |
Journal | The Journal of biological chemistry
(J Biol Chem)
Vol. 285
Issue 33
Pg. 25699-707
(Aug 13 2010)
ISSN: 1083-351X [Electronic] United States |
PMID | 20516064
(Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, Non-P.H.S.)
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Chemical References |
- 4-Nitroquinoline-1-oxide
- Exodeoxyribonucleases
- Exonucleases
- RecQ Helicases
- WRN protein, human
- Werner Syndrome Helicase
- Camptothecin
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Topics |
- 4-Nitroquinoline-1-oxide
(pharmacology)
- Blotting, Western
- Camptothecin
(pharmacology)
- Chromatography, Gel
- DNA Damage
(drug effects)
- Exodeoxyribonucleases
(chemistry, genetics, metabolism)
- Exonucleases
(genetics, metabolism)
- HeLa Cells
- Humans
- Immunoprecipitation
- Phosphorylation
- Polymerase Chain Reaction
- Protein Multimerization
(genetics, physiology)
- Protein Structure, Tertiary
(genetics, physiology)
- RecQ Helicases
(chemistry, genetics, metabolism)
- Werner Syndrome Helicase
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