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Gene Review

virA  -  sensor kinase

Agrobacterium fabrum str. C58

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Disease relevance of virA


High impact information on virA

  • The virA gene of Agrobacterium tumefaciens encodes an inner membrane that mediates the transcriptional activation of virulence genes in response to plant signal molecules [3].
  • The pTiAg162 virA locus was shown to be ineffective at directing vir gene induction, suggesting that this may in part contribute to the narrow host range conferred by this plasmid [4].
  • We have determined the nucleotide sequence of virA loci from limited (pTiAg162) and wide (pTiA6) host range tumor-inducing (Ti) plasmids, each of which encodes a single protein of 92,000 daltons [4].
  • Agrobacterium A136 harboring plasmid pGP159, which contains virA, virG, and a reporter virB:lacZ gene fusion, was mutagenized with UV light or nitrosoguanidine [5].
  • Crude protein extracts of induced and uninduced octopine wild-type strain of Agrobacterium tumefaciens, as well as several mutants of the virulence loci virA, -B, -G, -C, -D, and -E, were probed with single- and double-stranded synthetic oligodeoxynucleotides of different sequence and length in an electrophoretic retardation assay [6].

Chemical compound and disease context of virA


Biological context of virA


Associations of virA with chemical compounds

  • High nucleotide and amino acid sequence homologies were observed between pTiC58 virA and the virA sequences of three octopine-type plasmids [1].
  • The isolation was based on the activation of both virB::lacZ and virE::cat fusions by mutant virA loci in the absence of acetosyringone [7].
  • We also evaluated other phenolic compounds in induction assays and observed significant expression with syringealdehyde, a low level of expression with acetovanillone, and no expression with hydroxyacetophenone, similar to what occurs in A. tumefaciens strain A348 from which the virA clone was derived [10].
  • Since the trp promoter is not under virA-virG control, this result indicates that modification of VirG is necessary for its full activity [8].
  • Four of the mutations in the periplasmic domain, when introduced into the corresponding A6 virA sequence, caused a specific defect in the vir gene response to glucose [11].

Other interactions of virA


  1. Characterization of the virA virulence gene of the nopaline plasmid, pTiC58, of Agrobacterium tumefaciens. Morel, P., Powell, B.S., Rogowsky, P.M., Kado, C.I. Mol. Microbiol. (1989) [Pubmed]
  2. Transcriptional activation of Agrobacterium tumefaciens virulence gene promoters in Escherichia coli requires the A. tumefaciens RpoA gene, encoding the alpha subunit of RNA polymerase. Lohrke, S.M., Nechaev, S., Yang, H., Severinov, K., Jin, S.J. J. Bacteriol. (1999) [Pubmed]
  3. Membrane topology and functional analysis of the sensory protein VirA of Agrobacterium tumefaciens. Melchers, L.S., Regensburg-Tuïnk, T.J., Bourret, R.B., Sedee, N.J., Schilperoort, R.A., Hooykaas, P.J. EMBO J. (1989) [Pubmed]
  4. Characterization of the virA locus of Agrobacterium tumefaciens: a transcriptional regulator and host range determinant. Leroux, B., Yanofsky, M.F., Winans, S.C., Ward, J.E., Ziegler, S.F., Nester, E.W. EMBO J. (1987) [Pubmed]
  5. Mutants of Agrobacterium tumefaciens with elevated vir gene expression. Pazour, G.J., Ta, C.N., Das, A. Proc. Natl. Acad. Sci. U.S.A. (1991) [Pubmed]
  6. Mobilization of T-DNA from Agrobacterium to plant cells involves a protein that binds single-stranded DNA. Gietl, C., Koukolíková-Nicola, Z., Hohn, B. Proc. Natl. Acad. Sci. U.S.A. (1987) [Pubmed]
  7. Mutants of the Agrobacterium tumefaciens virA gene exhibiting acetosyringone-independent expression of the vir regulon. Ankenbauer, R.G., Best, E.A., Palanca, C.A., Nester, E.W. Mol. Plant Microbe Interact. (1991) [Pubmed]
  8. virG, an Agrobacterium tumefaciens transcriptional activator, initiates translation at a UUG codon and is a sequence-specific DNA-binding protein. Pazour, G.J., Das, A. J. Bacteriol. (1990) [Pubmed]
  9. virA and virG are the Ti-plasmid functions required for chemotaxis of Agrobacterium tumefaciens towards acetosyringone. Shaw, C.H., Ashby, A.M., Brown, A., Royal, C., Loake, G.J., Shaw, C.H. Mol. Microbiol. (1988) [Pubmed]
  10. Reconstitution of acetosyringone-mediated Agrobacterium tumefaciens virulence gene expression in the heterologous host Escherichia coli. Lohrke, S.M., Yang, H., Jin, S. J. Bacteriol. (2001) [Pubmed]
  11. Mutational analysis of the input domain of the VirA protein of Agrobacterium tumefaciens. Doty, S.L., Yu, M.C., Lundin, J.I., Heath, J.D., Nester, E.W. J. Bacteriol. (1996) [Pubmed]
  12. The VirA protein of Agrobacterium tumefaciens is autophosphorylated and is essential for vir gene regulation. Jin, S., Roitsch, T., Ankenbauer, R.G., Gordon, M.P., Nester, E.W. J. Bacteriol. (1990) [Pubmed]
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