XLF-Cernunnos promotes DNA ligase IV-XRCC4 re-adenylation following ligation

Riballo, Enriqueta, Woodbine, Lisa, Stiff, Thomas, Walker, Sarah A., Goodarzi, Aaron A. and Jeggo, Penny A. (2009) XLF-Cernunnos promotes DNA ligase IV-XRCC4 re-adenylation following ligation. Nucleic Acids Research, 37 (2). pp. 482-492. ISSN 0305-1048

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XLF-Cernunnos (XLF) is a component of the DNA ligase IV-XRCC4 (LX) complex, which functions during DNA non-homologous end joining (NHEJ). Here, we use biochemical and cellular approaches to probe the impact of XLF on LX activities. We show that XLF stimulates adenylation of LX complexes de-adenylated by pyrophosphate or following LX decharging during ligation. XLF enhances LX ligation activity in an ATP-independent and dependent manner. ATP-independent stimulation can be attributed to enhanced end-bridging. Whilst ATP alone fails to stimulate LX ligation activity, addition of XLF and ATP promotes ligation in a manner consistent with XLF-stimulated readenylation linked to ligation. We show that XLF is a weakly bound partner of the tightly associated LX complex and, unlike XRCC4, is dispensable for LX stability. 2BN cells, which have little, if any, residual XLF activity, show a 3-fold decreased ability to repair DNA double strand breaks covering a range of complexity. These findings strongly suggest that XLF is not essential for NHEJ but promotes LX adenylation and hence ligation. We propose a model in which XLF, by in situ recharging DNA ligase IV after the first ligation event, promotes double stranded ligation by a single LX complex.

Item Type: Article
Additional Information: GDSC282
Keywords: adenosine triphosphate; double stranded DNA; nucleic acid binding protein; polydeoxyribonucleotide synthase; protein XLF; pyrophosphate; unclassified drug; XRCC4 protein
Schools and Departments: School of Life Sciences > Sussex Centre for Genome Damage and Stability
Subjects: Q Science > QH Natural history > QH0301 Biology > QH0426 Genetics
Depositing User: Gee Wheatley
Date Deposited: 20 Nov 2009
Last Modified: 03 Jul 2019 01:04
URI: http://sro.sussex.ac.uk/id/eprint/2261

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