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Gene Review

virB11  -  type IV secretion system protein VirB11

Agrobacterium tumefaciens

 
 
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Disease relevance of virB11

 

High impact information on virB11

  • We propose that the virB9, virB10, and virB11 gene products function coordinately and stoichiometrically to enhance DNA transfer in a fashion specific for the T-DNA intermediate [4].
  • The DNA sequence analysis also revealed consensus mononucleotide binding domains in the deduced virB5 and virB11 gene products, suggesting that one or both of these proteins couple energy, by means of nucleotide triphosphate (NTP) hydrolysis, to T-DNA transport [1].
  • VirB11 protein was localized primarily to the cytoplasmic membrane by immunoblot analysis of membrane fractions [1].
  • These interactions were mapped onto the homology models to predict direct interactions between the hexameric interfaces of VirB4 and VirB11 such that the VirB4 C terminus stacks above VirB11 in the periplasm [5].
  • Here, by TrIP, we show that nucleoside triphosphate binding site (Walker A motif) mutations do not disrupt VirD4 substrate binding or transfer to VirB11, suggesting that these early reactions proceed independently of ATP binding or hydrolysis [6].
 

Chemical compound and disease context of virB11

 

Biological context of virB11

  • In the large virB-operon (9600 nucleotides) we have identified eleven open reading frames, designated virB1 to virB11 [8].
  • Due to the polarity of the transposon insertions, only the last gene in the operon, virB11, is known to provide an essential virulence function [9].
  • Interestingly, both a membrane protein (VirB4) and a potential cytoplasmic protein (VirB11) contain the consensus amino acid sequence of ATP-binding proteins [8].
  • The mutant genes did not exhibit a transdominant phenotype on tumor formation in bacteria that were expressing wild-type virB11 [7].
  • Our earlier studies showed that the IncQ broad-host-range plasmid RSF1010, which can be transferred from Agrobacterium cells to plant cells, inhibits the transfer of T-DNA from pTiA6 in a fashion that is reversed by overexpression of virB9, virB10, and virB11 [10].
 

Anatomical context of virB11

 

Associations of virB11 with chemical compounds

  • The maltose-binding protein-VirB11 fusion was able to complement a virB11 deletion mutant of A. tumefaciens for tumor formation and also localized properly to the inner membrane of A. tumefaciens [7].
  • To study the importance of the Walker nucleotide-binding site present in VirB11, mutations were generated to replace the conserved lysine residue with either alanine or arginine [7].
 

Other interactions of virB11

  • All dominant alleles were suppressed at least to some extent by multicopy expression of the virB9, virB10, and/or virB11 genes [13].
  • Two derivatives, A348 delta B4.4 and A348 delta B4.5, sustained a nonpolar deletion of the wild-type virB4 allele, as judged by Southern blot hybridization and immunoblot analyses with antibodies specific for VirB4, VirB5, VirB10, and VirB11 [14].
 

Analytical, diagnostic and therapeutic context of virB11

  • By co-immunoprecipitation, we supply evidence for VirD4 interactions with VirB4 and VirB11 independently of other T4SS subunits or intact Walker A motifs, and with the bitopic inner membrane subunit VirB10 [6].
  • X-ray crystallography revealed that homologues of the A. tumefaciens inner membrane-associated proteins VirB11 and VirD4 from H. pylori and R388, respectively, may form channels for substrate translocation or assembly of the transmembrane TFSS machinery [15].
  • In support of the titration model, a complex of native VirB11 and VirB11::GFP was recovered by precipitation with anti-GFP antibodies from detergent-solubilized A. tumefaciens cell extracts [3].

References

  1. A gene required for transfer of T-DNA to plants encodes an ATPase with autophosphorylating activity. Christie, P.J., Ward, J.E., Gordon, M.P., Nester, E.W. Proc. Natl. Acad. Sci. U.S.A. (1989) [Pubmed]
  2. Genetic and biochemical analysis of an endonuclease encoded by the IncN plasmid pKM101. Pohlman, R.F., Liu, F., Wang, L., Moré, M.I., Winans, S.C. Nucleic Acids Res. (1993) [Pubmed]
  3. Self-assembly of the Agrobacterium tumefaciens VirB11 traffic ATPase. Rashkova, S., Zhou, X.R., Chen, J., Christie, P.J. J. Bacteriol. (2000) [Pubmed]
  4. Activity of the Agrobacterium T-DNA transfer machinery is affected by virB gene products. Ward, J.E., Dale, E.M., Binns, A.N. Proc. Natl. Acad. Sci. U.S.A. (1991) [Pubmed]
  5. Topology of the VirB4 C Terminus in the Agrobacterium tumefaciens VirB/D4 Type IV Secretion System. Draper, O., Middleton, R., Doucleff, M., Zambryski, P.C. J. Biol. Chem. (2006) [Pubmed]
  6. Energetic components VirD4, VirB11 and VirB4 mediate early DNA transfer reactions required for bacterial type IV secretion. Atmakuri, K., Cascales, E., Christie, P.J. Mol. Microbiol. (2004) [Pubmed]
  7. Agrobacterium tumefaciens VirB11 protein requires a consensus nucleotide-binding site for function in virulence. Stephens, K.M., Roush, C., Nester, E. J. Bacteriol. (1995) [Pubmed]
  8. Analysis of the complete nucleotide sequence of the Agrobacterium tumefaciens virB operon. Thompson, D.V., Melchers, L.S., Idler, K.B., Schilperoort, R.A., Hooykaas, P.J. Nucleic Acids Res. (1988) [Pubmed]
  9. Complementation analysis of Agrobacterium tumefaciens Ti plasmid virB genes by use of a vir promoter expression vector: virB9, virB10, and virB11 are essential virulence genes. Ward, J.E., Dale, E.M., Christie, P.J., Nester, E.W., Binns, A.N. J. Bacteriol. (1990) [Pubmed]
  10. Inhibition of VirB-mediated transfer of diverse substrates from Agrobacterium tumefaciens by the IncQ plasmid RSF1010. Binns, A.N., Beaupré, C.E., Dale, E.M. J. Bacteriol. (1995) [Pubmed]
  11. Structural characterization of the virB operon on the hairy-root-inducing plasmid A4. Liang, Y., Aoyama, T., Oka, A. DNA Res. (1998) [Pubmed]
  12. Interactions of VirB9, -10, and -11 with the membrane fraction of Agrobacterium tumefaciens: solubility studies provide evidence for tight associations. Finberg, K.E., Muth, T.R., Young, S.P., Maken, J.B., Heitritter, S.M., Binns, A.N., Banta, L.M. J. Bacteriol. (1995) [Pubmed]
  13. Suppression of mutant phenotypes of the Agrobacterium tumefaciens VirB11 ATPase by overproduction of VirB proteins. Zhou, X.R., Christie, P.J. J. Bacteriol. (1997) [Pubmed]
  14. The Agrobacterium tumefaciens virB4 gene product is an essential virulence protein requiring an intact nucleoside triphosphate-binding domain. Berger, B.R., Christie, P.J. J. Bacteriol. (1993) [Pubmed]
  15. Bacterial secrets of secretion: EuroConference on the biology of type IV secretion processes. Baron, C., OCallaghan, D., Lanka, E. Mol. Microbiol. (2002) [Pubmed]
 
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