title: Role of the VirA histidine autokinase of Agrobacterium tumefaciens in the initial steps of pathogenesis.
abstract: Histidine kinases serve as critical environmental sensing modules, and despite their designation as simple two-component modules, their functional roles are remarkably diverse. In Agrobacterium tumefaciens pathogenesis, VirA serves with VirG as the initiating sensor/transcriptional activator for inter-kingdom gene transfer and transformation of higher plants. Through responses to three separate signal inputs, low pH, sugars, and phenols, A. tumefaciens commits to pathogenesis in virtually all flowering plants. However, how these three signals are integrated to regulate the response and why these signals might be diagnostic for susceptible cells across such a broad host-range remains poorly understood. Using a homology model of the VirA linker region, we provide evidence for coordinated long-range transmission of inputs perceived both outside and inside the cell through the creation of targeted VirA truncations. Further, our evidence is consistent with signal inputs weakening associations between VirA domains to position the active site histidine for phosphate transfer. This mechanism requires long-range regulation of inter-domain stability and the transmission of input signals through a common integrating domain for VirA signal transduction.
authors.affiliation: Lynn Lab, Department of Chemistry and Biology, Emory University Atlanta, GA, USA.
authors.forename: Yi-Han
authors.initials: YH
authors.lastname: Lin
authors.affiliation: Lynn Lab, Department of Chemistry and Biology, Emory University Atlanta, GA, USA.
authors.forename: B Daniel
authors.initials: BD
authors.lastname: Pierce
authors.affiliation: Lynn Lab, Department of Chemistry and Biology, Emory University Atlanta, GA, USA.
authors.forename: Fang
authors.initials: F
authors.lastname: Fang
authors.affiliation: Binns Lab, Department of Biology, Plant Sciences Institute, University of Pennsylvania Philadelphia, PA, USA.
authors.forename: Arlene
authors.initials: A
authors.lastname: Wise
authors.affiliation: Binns Lab, Department of Biology, Plant Sciences Institute, University of Pennsylvania Philadelphia, PA, USA.
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Binns
authors.affiliation: Lynn Lab, Department of Chemistry and Biology, Emory University Atlanta, GA, USA.
authors.forename: David G
authors.initials: DG
authors.lastname: Lynn
keywords: Agrobacterium; GAF domain; VirA; pathogenesis; signal transduction; two-component system