DNA binding of Xrcc4 protein is associated with V(D)J recombination but not with stimulation of DNA ligase IV activity.
Mammalian cells are protected from the effects of DNA double-strand breaks by end-joining repair. Cells lacking the Xrcc4 protein are hypersensitive to agents that induce DNA double-strand breaks, and are unable to complete V(D)J recombination. The residual repair of broken DNA ends in XRCC4-deficient cells requires short sequence homologies, thus possibly implicating Xrcc4 in end alignment. We show that Xrcc4 binds DNA, and prefers DNA with nicks or broken ends. Xrcc4 also binds to DNA ligase IV and enhances its joining activity. This stimulatory effect is shown to occur at the adenylation of the enzyme. DNA binding of Xrcc4 is correlated with its complementation of the V(D)J recombination defects in XRCC4-deficient cells, but is not required for stimulation of DNA ligase IV. Thus, the ability of Xrcc4 to bind to DNA suggests functions independent of DNA ligase IV.
Modesti
M
M
Laboratory of Molecular Biology, Building 5 Room 241, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0540, USA.
Hesse
J E
JE
Gellert
M
M
D000818:Animals; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D004247:DNA / Q000378:metabolism*; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000378:metabolism*; D004254:DNA Nucleotidyltransferases / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D010766:Phosphorylation; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D045567:VDJ Recombinases
D017931:DNA Primers; D004268:DNA-Binding Proteins; C000607893:LIG4 protein, human; D011994:Recombinant Proteins; C101467:XRCC4 protein, human; D004247:DNA; D004254:DNA Nucleotidyltransferases; D045567:VDJ Recombinases; D011088:DNA Ligases; D000072481:DNA Ligase ATP