This family consists of several T-DNA border endonuclease VirD1 proteins which appear to be found exclusively in Agrobacterium species. Agrobacterium, a plant pathogen, is capable to stably transform the plant cell with a segment of its own DNA called T-DNA (transferred DNA). This process depends, among others, on the specialised bacterial virulence proteins VirD1 and VirD2 that excise the T-DNA from its adjacent sequences. VirD1 is thought to interact with VirD2 in this process [1].

1: Interaction of the DNA modifying proteins VirD1 and VirD2 of Agrobacterium tumefaciens: analysis by subcellular localization in mammalian cells. Relic B, Andjelkovic M, Rossi L, Nagamine Y, Hohn B; Proc Natl Acad Sci U S A 1998;95:9105-9110. PMID:9689041