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Gene Review

virD2  -  type IV secretion system T-DNA border...

Agrobacterium fabrum str. C58

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Disease relevance of virD2


High impact information on virD2

  • We report here that the virD operon encodes a site-specific endonuclease that cleaves at a unique site within each of the 24 bp direct repeats that flank the T-DNA [4].
  • Agrolistically transformed tobacco calli were obtained after codelivery of virD1 and virD2 genes together with a selectable marker flanked by border sequences [5].
  • The virulence genes virD1 and virD2 from Agrobacterium tumefaciens that are required in bacteria for excision of T-strands from the tumor-inducing plasmid were placed under the control of the CaMV35S promoter and codelivered with a target plasmid containing border sequences flanking the gene of interest [5].
  • DNA modifying enzymes of Agrobacterium tumefaciens: effect of DNA topoisomerase, restriction endonuclease, and unique DNA endonuclease on plasmid and plant DNA [6].
  • To the left of cagII in this cosmid were genes for homologues of HsIU (heat-shock protein) and Era (essential GTPase); to the right of cagII were homologues of genes for a type I restriction endonuclease and ion transport functions [7].

Chemical compound and disease context of virD2


Biological context of virD2

  • Comparative nucleotide sequence analyses of virD2 showed that the first 684 bp were 81% homologous to virD2 of an octopine Ti plasmid whereas the remaining 660 bp were only 44% homologous [1].
  • However, a non-polar insertion immediately after bp 684 of the 1344 bp open reading frame of virD2 did not inhibit endonucleolytic cleavage but still caused a loss of virulence [1].
  • Some insertional mutations in virD2 prevented T-DNA border endonucleolytic cleavage and produced an avirulent phenotype [1].
  • To test this system, we introduced a wild-type virD2 gene into the A. tumefaciens chromosome at the pgl/picA locus [10].
  • Direct repeats define the T-DNA ends; transfer begins when the VirD2 endonuclease produces a site-specific nick in the right-hand border repeat and attaches to the 5' end of the nicked strand [11].

Associations of virD2 with chemical compounds

  • A T-DNA subfragment cloned in pBR322 is cleaved by a restriction endonuclease at a unique central site and target DNA (a kanamycin resistance marker) is ligated into this site [12].

Other interactions of virD2

  • The regions within virD2 contributing to T-DNA processing and virulence were investigated [1].
  • When extra copies of the virD1 and virD2 genes were present in an A. tumefaciens strain carrying a Ti plasmid, increased amounts of T-strand and nicked molecules could be detected at early stages of vir induction [13].
  • The virD2 and ipt primer pairs did not interfere with each other when included in the same PCR amplification, and this permitted simultaneous detection of both genes in a single reaction [14].
  • We propose that product(s) of this gene have recombinase or endonuclease activity which specifically recognizes the 25 bp terminal repeats of T-DNA [15].

Analytical, diagnostic and therapeutic context of virD2


  1. VirD2 gene product from the nopaline plasmid pTiC58 has at least two activities required for virulence. Steck, T.R., Lin, T.S., Kado, C.I. Nucleic Acids Res. (1990) [Pubmed]
  2. A bacterial peptide acting as a plant nuclear targeting signal: the amino-terminal portion of Agrobacterium VirD2 protein directs a beta-galactosidase fusion protein into tobacco nuclei. Herrera-Estrella, A., Van Montagu, M., Wang, K. Proc. Natl. Acad. Sci. U.S.A. (1990) [Pubmed]
  3. Studies on the bacteriophage PS8 of Agrobacterium tumefaciens (Smith and Townsend) Conn: physico-chemical properties of its DNA. Knopf, U.C. Microbios (1976) [Pubmed]
  4. The virD operon of Agrobacterium tumefaciens encodes a site-specific endonuclease. Yanofsky, M.F., Porter, S.G., Young, C., Albright, L.M., Gordon, M.P., Nester, E.W. Cell (1986) [Pubmed]
  5. "Agrolistic" transformation of plant cells: integration of T-strands generated in planta. Hansen, G., Chilton, M.D. Proc. Natl. Acad. Sci. U.S.A. (1996) [Pubmed]
  6. DNA modifying enzymes of Agrobacterium tumefaciens: effect of DNA topoisomerase, restriction endonuclease, and unique DNA endonuclease on plasmid and plant DNA. LeBon, J.M., Kado, C.I., Rosenthal, L.J., Chirikjian, J.G. Proc. Natl. Acad. Sci. U.S.A. (1978) [Pubmed]
  7. Analyses of the cag pathogenicity island of Helicobacter pylori. Akopyants, N.S., Clifton, S.W., Kersulyte, D., Crabtree, J.E., Youree, B.E., Reece, C.A., Bukanov, N.O., Drazek, E.S., Roe, B.A., Berg, D.E. Mol. Microbiol. (1998) [Pubmed]
  8. Mutational analysis of Agrobacterium tumefaciens virD2: tyrosine 29 is essential for endonuclease activity. Vogel, A.M., Das, A. J. Bacteriol. (1992) [Pubmed]
  9. Restriction endonuclease mapping of the octopine tumor-inducing plasmid pTiAch5 of Agrobacterium tumefaciens. De Vos, G., De Beuckeleer, M., Van Montagu, M., Schell, J. Plasmid (1981) [Pubmed]
  10. Novel constructions to enable the integration of genes into the Agrobacterium tumefaciens C58 chromosome. Lee, L.Y., Humara, J.M., Gelvin, S.B. Mol. Plant Microbe Interact. (2001) [Pubmed]
  11. A nuclear localization signal and the C-terminal omega sequence in the Agrobacterium tumefaciens VirD2 endonuclease are important for tumor formation. Shurvinton, C.E., Hodges, L., Ream, W. Proc. Natl. Acad. Sci. U.S.A. (1992) [Pubmed]
  12. Site-specific insertion of genes into T-DNA of the Agrobacterium tumor-inducing plasmid: an approach to genetic engineering of higher plant cells. Matzke, A.J., Chilton, M.D. J. Mol. Appl. Genet. (1981) [Pubmed]
  13. Overexpression of virD1 and virD2 genes in Agrobacterium tumefaciens enhances T-complex formation and plant transformation. Wang, K., Herrera-Estrella, A., Van Montagu, M. J. Bacteriol. (1990) [Pubmed]
  14. Universal PCR primers for detection of phytopathogenic Agrobacterium strains. Haas, J.H., Moore, L.W., Ream, W., Manulis, S. Appl. Environ. Microbiol. (1995) [Pubmed]
  15. The promoter proximal region in the virD locus of Agrobacterium tumefaciens is necessary for the plant-inducible circularization of T-DNA. Yamamoto, A., Iwahashi, M., Yanofsky, M.F., Nester, E.W., Takebe, I., Machida, Y. Mol. Gen. Genet. (1987) [Pubmed]
  16. Association of the virD2 protein with the 5' end of T strands in Agrobacterium tumefaciens. Young, C., Nester, E.W. J. Bacteriol. (1988) [Pubmed]
  17. Restriction endonuclease mapping of a plasmid that confers oncogenicity upon Agrobacterium tumefaciens strain B6-806. Chilton, M.D., Montoya, A.L., Merlo, D.J., Drummond, M.H., Nutter, R., Gordon, M.P., Nester, E.W. Plasmid (1978) [Pubmed]
  18. Mapping of promoter-proximal regions by in vitro transcription of two Agrobacterium tumefaciens Ti-plasmids. Risuelo, G., di Mauro, E. Mol. Biol. Rep. (1984) [Pubmed]
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