A mutation in the receiver domain of the Agrobacterium tumefaciens transcriptional regulator VirG increases its affinity for operator DNA

Mol Microbiol. 1994 Apr;12(1):23-30. doi: 10.1111/j.1365-2958.1994.tb00991.x.


We fused the wild-type Agrobacterium tumefaciens virG gene and the constitutive virGN54D allele to the malE gene of Escherichia coli, and studied the binding of MBP-VirG fusions to the autoregulated virG promoter. MBP-VirGN54D protein bound this promoter with 10-fold higher affinity than MBP-VirG, and bound to vir box I with eightfold higher affinity than to vir box III. Disruption of vir box III did not alter the affinity for vir box I, suggesting a lack of cooperativity between these sites. We provide evidence that protein bound at a single vir box may have a higher oligomeric state than non-bound protein, and that a DNA distortion adjacent to vir box I may occur during activation.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Agrobacterium tumefaciens / genetics*
  • Bacterial Proteins
  • Base Sequence
  • DNA, Bacterial / metabolism*
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / metabolism
  • Escherichia coli
  • Gene Expression Regulation, Bacterial*
  • Genes, Bacterial*
  • Genes, Regulator*
  • Molecular Sequence Data
  • Operator Regions, Genetic*
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism
  • Phosphorylation
  • Promoter Regions, Genetic
  • Protein Binding
  • Protein Processing, Post-Translational
  • Recombinant Fusion Proteins / biosynthesis
  • Regulatory Sequences, Nucleic Acid
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism


  • Bacterial Proteins
  • DNA, Bacterial
  • DNA-Binding Proteins
  • Phosphoproteins
  • Recombinant Fusion Proteins
  • Transcription Factors
  • virG protein, Shigella flexneri