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Phosphorylation of linker histones by DNA-dependent protein kinase is required for DNA ligase IV-dependent ligation in the presence of histone H1
journal contribution
posted on 2023-06-07, 21:51 authored by Boris Kysela, Miroslav Chovanec, Penny JeggoDNA nonhomologous end-joining in vivo requires the DNA-dependent protein kinase (DNA-PK) and DNA ligase IV/XRCC4 (LX) complexes. Here, we have examined the impact of histone octamers and linker histone H1 on DNA end-joining in vitro. Packing of the DNA substrate into dinucleosomes does not significantly inhibit ligation by LX. However, LX ligation activity is substantially reduced by the incorporation of linker histones. This inhibition is independent of the presence of core histone octamers and cannot be restored by addition of Ku alone but can be partially rescued by DNA-PK. The kinase activity of DNA-PK is essential for the recovery of end-joining. DNA-PK efficiently phosphorylates histone H1. Phosphorylated histone H1 has a reduced affinity for DNA and a decreased capacity to inhibit end-joining. Our findings raise the possibility that DNA-PK may act as a linker histone kinase by phosphorylating linker histones in the vicinity of a DNA break and coupling localized histone H1 release from DNA ends, with the recruitment of LX to carry out double-stranded ligation. Thus, by using histone H1-bound DNA as a template, we have reconstituted the end-joining step of DNA nonhomologous end-joining in vitro with a requirement for DNA-PK.
History
Publication status
- Published
Journal
Proceedings of the National Academy of SciencesISSN
1091-6490Publisher
National Academy of SciencesExternal DOI
Issue
6Volume
102Page range
1877-1882Department affiliated with
- Sussex Centre for Genome Damage Stability Publications
Full text available
- No
Peer reviewed?
- Yes