Localization of the VirA domain involved in acetosyringone-mediated vir gene induction in Agrobacterium tumefaciens.

The VirA protein of Agrobacterium tumefaciens is thought to be a receptor for plant phenolic compounds such as acetosyringone. Although it is not known whether the interaction between VirA and the phenolics is direct or requires other phenolic-binding proteins, it is shown in this study that the first 280 amino acids of the VirA protein are not essential for the acetosyringone mediated vir gene induction response. Considering the fact that the cytoplasmic region between the amino acids 283 and 304 is highly conserved between the different VirA proteins, and that deletion of this region abolishes VirA activity, we suggest that the acetosyringone receptor domain is located in this cytoplasmic domain of the VirA protein.