XLS (c9orf142) is a new component of mammalian DNA double-stranded break repair.
Repair of double-stranded DNA breaks (DSBs) in mammalian cells primarily occurs by the non-homologous end-joining (NHEJ) pathway, which requires seven core proteins (Ku70/Ku86, DNA-PKcs (DNA-dependent protein kinase catalytic subunit), Artemis, XRCC4-like factor (XLF), XRCC4 and DNA ligase IV). Here we show using combined affinity purification and mass spectrometry that DNA-PKcs co-purifies with all known core NHEJ factors. Furthermore, we have identified a novel evolutionary conserved protein associated with DNA-PKcs-c9orf142. Computer-based modelling of c9orf142 predicted a structure very similar to XRCC4, hence we have named c9orf142-XLS (XRCC4-like small protein). Depletion of c9orf142/XLS in cells impaired DSB repair consistent with a defect in NHEJ. Furthermore, c9orf142/XLS interacted with other core NHEJ factors. These results demonstrate the existence of a new component of the NHEJ DNA repair pathway in mammalian cells.
MRC Toxicology Unit, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK.
A
A
Craxton
MRC Toxicology Unit, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK.
J
J
Somers
MRC Toxicology Unit, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK.
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D
Munnur
MRC Toxicology Unit, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK.
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R
Jukes-Jones
MRC Toxicology Unit, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK.
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K
Cain
MRC Toxicology Unit, Hodgkin Building, Lancaster Road, Leicester LE1 9HN, UK.
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M
Malewicz
D002460:Cell Line; D002846:Chromatography, Affinity; D003198:Computer Simulation; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair / Q000235:genetics / Q000502:physiology; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D034741:RNA, Small Interfering; D053719:Tandem Mass Spectrometry
D004268:DNA-Binding Proteins; C000595075:PAXX protein, human; D034741:RNA, Small Interfering