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Werner Protein Is a Target of DNA-dependent Protein Kinase in Vivo and in Vitro, and Its Catalytic Activities Are Regulated by Phosphorylation
- Source :
- Journal of Biological Chemistry. 277:18291-18302
- Publication Year :
- 2002
- Publisher :
- Elsevier BV, 2002.
-
Abstract
- Human Werner Syndrome is characterized by early onset of aging, elevated chromosomal instability, and a high incidence of cancer. Werner protein (WRN) is a member of the recQ gene family, but unlike other members of the recQ family, it contains a unique 3'-->5' exonuclease activity. We have reported previously that human Ku heterodimer interacts physically with WRN and functionally stimulates WRN exonuclease activity. Because Ku and DNA-PKcs, the catalytic subunit of DNA-dependent protein kinase (DNA-PK), form a complex at DNA ends, we have now explored the possibility of functional modulation of WRN exonuclease activity by DNA-PK. We find that although DNA-PKcs alone does not affect the WRN exonuclease activity, the additional presence of Ku mediates a marked inhibition of it. The inhibition of WRN exonuclease by DNA-PKcs requires the kinase activity of DNA-PKcs. WRN is a target for DNA-PKcs phosphorylation, and this phosphorylation requires the presence of Ku. We also find that treatment of recombinant WRN with a Ser/Thr phosphatase enhances WRN exonuclease and helicase activities and that WRN catalytic activity can be inhibited by rephosphorylation of WRN with DNA-PK. Thus, the level of phosphorylation of WRN appears to regulate its catalytic activities. WRN forms a complex, both in vitro and in vivo, with DNA-PKC. WRN is phosphorylated in vivo after treatment of cells with DNA-damaging agents in a pathway that requires DNA-PKcs. Thus, WRN protein is a target for DNA-PK phosphorylation in vitro and in vivo, and this phosphorylation may be a way of regulating its different catalytic activities, possibly in the repair of DNA dsb.
- Subjects :
- Exonuclease
congenital, hereditary, and neonatal diseases and abnormalities
Insecta
Werner Syndrome Helicase
Protein subunit
Phosphatase
DNA-Activated Protein Kinase
Protein Serine-Threonine Kinases
Biochemistry
Catalysis
Catalytic Domain
medicine
Animals
Humans
Phosphorylation
Kinase activity
Protein kinase A
Molecular Biology
DNA Primers
Werner syndrome
Base Sequence
RecQ Helicases
biology
DNA Helicases
Nuclear Proteins
nutritional and metabolic diseases
Helicase
Cell Biology
medicine.disease
Molecular biology
Recombinant Proteins
Cell biology
DNA-Binding Proteins
enzymes and coenzymes (carbohydrates)
Exodeoxyribonucleases
biology.protein
Werner Syndrome
DNA Damage
HeLa Cells
Subjects
Details
- ISSN :
- 00219258
- Volume :
- 277
- Database :
- OpenAIRE
- Journal :
- Journal of Biological Chemistry
- Accession number :
- edsair.doi.dedup.....be62a822e8586c6f07786c429c3f702e