Removal of VirD2 from a synthetic T-DNA complex of Agrobacterium by the host DNA repair protein TDP2.

TDP2 specifically cleaves VirD2 from fluorescently labeled synthetic VirD2–ssDNA T-complexes, with Mg2+-dependent activity requiring TDP2’s conserved C-terminal histidine residue.

• Why it matters: VirD2 must be removed from the T-complex before T-DNA 5'-end ligation to host genomic DNA, but whether plant TDP2 directly performs this step was unproven.
• What they did: The authors built an in vitro system using fluorescently labeled VirD2–ssDNA complexes and tested DNA substrate requirements and VirD2 removal by mammalian or plant TDP2, including Mg2+ dependence and a C-terminal histidine requirement.
• The result: Plant TDP2 can remove VirD2 from synthetic T-complexes, strongly supporting a pathway for VirD2 removal from T-DNA prior to integration into the plant genome.