A noncatalytic function of the ligation complex during nonhomologous end joining

Nonhomologous end joining is the primary deoxyribonucleic acid (DNA) double-strand break repair pathway in multicellular eukaryotes. To initiate repair, Ku binds DNA ends and recruits the DNA-dependent protein kinase (DNA-PK) catalytic subunit (DNA-PKcs) forming the holoenzyme. Early end synapsis is...

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Vydáno v:The Journal of cell biology Ročník 200; číslo 2; s. 173
Hlavní autoři: Cottarel, Jessica, Frit, Philippe, Bombarde, Oriane, Salles, Bernard, Négrel, Aurélie, Bernard, Stéphanie, Jeggo, Penny A, Lieber, Michael R, Modesti, Mauro, Calsou, Patrick
Médium: Journal Article
Jazyk:angličtina
Vydáno: United States 21.01.2013
Témata:
Cell-Free System - metabolism
Cells, Cultured
DNA Damage
DNA End-Joining Repair - physiology
DNA Helicases - metabolism
DNA Helicases - physiology
DNA Ligase ATP
DNA Ligases - metabolism
DNA Ligases - physiology
DNA Repair Enzymes - metabolism
DNA Repair Enzymes - physiology
DNA-Activated Protein Kinase - metabolism
DNA-Binding Proteins - metabolism
DNA-Binding Proteins - physiology
Genomic Instability
Holoenzymes
Humans
Ku Autoantigen
Phosphorylation
ISSN:1540-8140, 1540-8140
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Popis
Shrnutí:Nonhomologous end joining is the primary deoxyribonucleic acid (DNA) double-strand break repair pathway in multicellular eukaryotes. To initiate repair, Ku binds DNA ends and recruits the DNA-dependent protein kinase (DNA-PK) catalytic subunit (DNA-PKcs) forming the holoenzyme. Early end synapsis is associated with kinase autophosphorylation. The XRCC4 (X4)-DNA Ligase IV (LIG4) complex (X4LIG4) executes the final ligation promoted by Cernunnos (Cer)-X4-like factor (XLF). In this paper, using a cell-free system that recapitulates end synapsis and DNA-PKcs autophosphorylation, we found a defect in both activities in human cell extracts lacking LIG4. LIG4 also stimulated the DNA-PKcs autophosphorylation in a reconstitution assay with purified components. We additionally uncovered a kinase autophosphorylation defect in LIG4-defective cells that was corrected by ectopic expression of catalytically dead LIG4. Finally, our data support a contribution of Cer-XLF to this unexpected early role of the ligation complex in end joining. We propose that productive end joining occurs by early formation of a supramolecular entity containing both DNA-PK and X4LIG4-Cer-XLF complexes on DNA ends.
Bibliografie:ObjectType-Article-1
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ISSN:1540-8140
1540-8140
DOI:10.1083/jcb.201203128