Werner protein cooperates with the XRCC4-DNA ligase IV complex in end-processing.
Werner syndrome is a rare human disease characterized by the premature onset of aging-associated pathologies, cancer predisposition, and genomic instability. The Werner protein (WRN), which is defective in Werner syndrome ( WS) patients, belongs to the RecQ family helicases and interacts with several DNA metabolic proteins, including DNA repair factors and telomere associated proteins. Nonhomologous end-joining (NHEJ) is an important pathway in the repair of DNA double strand breaks (DSBs), and the DNA-PK complex, composed of the heterodimer Ku 70/86 and the DNA-PK catalytic subunit (DNA-PKcs), together with the XRCC4-DNA ligase IV complex (X4L4), are major factors. One of the most prominent protein interactions of WRN is with Ku 70/86, and it is possible that WRN is involved in NHEJ via its associations with Ku 70/86 and DNA-PKcs. This study demonstrates that WRN physically interacts with the major NHEJ factor, X4L4, which stimulates WRN exonuclease but not its helicase activity. The human RecQ helicase, BLM, which possesses only helicase activity, does not bind to X4L4, and its helicase activity is not affected by X4L4. In a DNA end-joining assay, we find that a substrate, which is processed by WRN, is ligated by X4L4, thus further supporting the significance of their functional interaction.
Laboratory of Molecular Gerontology, National Institute on Aging, NIH, 5600 Nathan Shock Drive, Baltimore, Maryland 21224, USA.
Rika
R
Kusumoto
Lala
L
Dawut
Caterina
C
Marchetti
Jae
J
Wan Lee
Alessandro
A
Vindigni
Dale
D
Ramsden
Vilhelm A
VA
Bohr
D002467:Cell Nucleus / Q000201:enzymology; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000378:metabolism*; D004260:DNA Repair; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005090:Exodeoxyribonucleases / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D011499:Protein Processing, Post-Translational; D053484:RecQ Helicases / Q000235:genetics / Q000378:metabolism*; D014898:Werner Syndrome / Q000235:genetics* / Q000378:metabolism; D000071657:Werner Syndrome Helicase
D004268:DNA-Binding Proteins; C000607893:LIG4 protein, human; C508551:NHEJ1 protein, human; C101467:XRCC4 protein, human; D004247:DNA; D005090:Exodeoxyribonucleases; D053484:RecQ Helicases; C098785:WRN protein, human; D000071657:Werner Syndrome Helicase; D011088:DNA Ligases; D045643:DNA Repair Enzymes; D000072481:DNA Ligase ATP