Functional Interaction between the Werner Syndrome Protein and DNA Polymerase δ

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 97; no. 9; pp. 4603 - 4608
• Main Authors: Kamath-Loeb, A. S., Johansson, E., Burgers, P. M. J., Loeb, L. A.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 25.04.2000; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences
• Subjects: Aging; Base Sequence; Binding Sites; Biochemistry; Biological Sciences; Cancer; Deoxyribonucleic acid; Disease; DNA; DNA damage; DNA helicase; DNA Helicases - chemistry; DNA Helicases - metabolism; DNA Helicases/chemistry/metabolism; DNA Polymerase III - chemistry; DNA Polymerase III - metabolism; DNA Polymerase III/chemistry/metabolism; DNA Primers; DNA repair; DNA Replication; Enzymes; Exodeoxyribonucleases; Gels; Genomics; Humans; Kinetics; Molecular Sequence Data; Nucleotides; Polymerization; Proliferating Cell Nuclear Antigen - metabolism; RecQ Helicases; Saccharomyces cerevisiae; Templates, Genetic; Werner Syndrome - genetics; Werner Syndrome Helicase; WS gene; Yeasts; Genetic; Templates
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.97.9.4603

Werner Syndrome (WS) is an inherited disease characterized by premature onset of aging, increased cancer incidence, and genomic instability. The WS gene encodes a 1,432-amino acid polypeptide (WRN) with a central domain homologous to the RecQ family of DNA helicases. Purified WRN unwinds DNA with 3′→ 5′polarity, and also possesses 3′→ 5′exonuclease activity. Elucidation of the physiologic function(s) of WRN may be aided by the identification of WRN-interacting proteins. We show here that WRN functionally interacts with DNA polymerase δ (pol δ ), a eukaryotic polymerase required for DNA replication and DNA repair. WRN increases the rate of nucleotide incorporation by pol δ in the absence of proliferating cell nuclear antigen (PCNA) but does not stimulate the activity of eukaryotic DNA polymerases α or ε , or a variety of other DNA polymerases. Moreover, we show that functional interaction with WRN is mediated through the third subunit of pol δ : i.e., Pol32p of Saccharomyces cerevisae, corresponding to the recently identified p66 subunit of human pol δ . Absence of the third subunit abrogates stimulation by WRN, and stimulation is restored by reconstituting the three-subunit enzyme. Our findings suggest that WRN may facilitate pol δ -mediated DNA replication and/or DNA repair and that disruption of WRN-pol δ interaction in WS cells may contribute to the previously observed S-phase defects and/or the unusual sensitivity to a limited number of DNA damaging agents.