title: C-terminal region of bacterial Ku controls DNA bridging, DNA threading and recruitment of DNA ligase D for double strand breaks repair.
abstract: Non-homologous end joining is a ligation process repairing DNA double strand breaks in eukaryotes and many prokaryotes. The ring structured eukaryotic Ku binds DNA ends and recruits other factors which can access DNA ends through the threading of Ku inward the DNA, making this protein a key ingredient for the scaffolding of the NHEJ machinery. However, this threading ability seems unevenly conserved among bacterial Ku. As bacterial Ku differ mainly by their C-terminus, we evaluate the role of this region in the loading and the threading abilities of Bacillus subtilis Ku and the stimulation of the DNA ligase LigD. We identify two distinct sub-regions: a ubiquitous minimal C-terminal region and a frequent basic C-terminal extension. We show that truncation of one or both of these sub-regions in Bacillus subtilis Ku impairs the stimulation of the LigD end joining activity in vitro. We further demonstrate that the minimal C-terminus is required for the Ku-LigD interaction, whereas the basic extension controls the threading and DNA bridging abilities of Ku. We propose that the Ku basic C-terminal extension increases the concentration of Ku near DNA ends, favoring the recruitment of LigD at the break, thanks to the minimal C-terminal sub-region.
authors.affiliation: Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
authors.forename: Stephen
authors.initials: S
authors.lastname: McGovern
authors.affiliation: UMR 8126, CNRS, Gustave Roussy Université Paris Sud, Université Paris-Saclay, F-94805 Villejuif, France.
authors.forename: Sonia
authors.initials: S
authors.lastname: Baconnais
authors.affiliation: SOLEIL Synchrotron, F- 91192 Gif-sur-Yvette, INRA-URBIA, F-44316 Nantes, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Roblin
authors.affiliation: MaIAGE, INRA, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Nicolas
authors.affiliation: I2BC, iBiTec-S, CEA Saclay, UMR 9198, F-91191 Gif-sur-Yvette, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Drevet
authors.affiliation: Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
authors.forename: Héloïse
authors.initials: H
authors.lastname: Simonson
authors.affiliation: UMR 8126, CNRS, Gustave Roussy Université Paris Sud, Université Paris-Saclay, F-94805 Villejuif, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Piétrement
authors.affiliation: I2BC, iBiTec-S, CEA Saclay, UMR 9198, F-91191 Gif-sur-Yvette, France.
authors.forename: Jean-Baptiste
authors.initials: JB
authors.lastname: Charbonnier
authors.affiliation: UMR 8126, CNRS, Gustave Roussy Université Paris Sud, Université Paris-Saclay, F-94805 Villejuif, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Le Cam
authors.affiliation: Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Noirot
authors.affiliation: Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France francois.lecointe@jouy.inra.fr.
authors.forename: François
authors.initials: F
authors.lastname: Lecointe