title: Agrobacterium tumefaciens recognizes its host environment using ChvE to bind diverse plant sugars as virulence signals.
abstract: Agrobacterium tumefaciens is a broad host range plant pathogen that combinatorially recognizes diverse host molecules including phenolics, low pH, and aldose monosaccharides to activate its pathogenic pathways. Chromosomal virulence gene E (chvE) encodes a periplasmic-binding protein that binds several neutral sugars and sugar acids, and subsequently interacts with the VirA/VirG regulatory system to stimulate virulence (vir) gene expression. Here, a combination of genetics, X-ray crystallography, and isothermal calorimetry reveals how ChvE binds the different monosaccharides and also shows that binding of sugar acids is pH dependent. Moreover, the potency of a sugar for vir gene expression is modulated by a transport system that also relies on ChvE. These two circuits tune the overall system to respond to sugar concentrations encountered in vivo. Finally, using chvE mutants with restricted sugar specificities, we show that there is host variation in regard to the types of sugars that are limiting for vir induction.
authors.affiliation: Department of Biochemistry and Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors.forename: Xiaozhen
authors.initials: X
authors.lastname: Hu
authors.forename: Jinlei
authors.initials: J
authors.lastname: Zhao
authors.forename: William F
authors.initials: WF
authors.lastname: DeGrado
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Binns
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016960:Agrobacterium tumefaciens / Q000378:metabolism* / Q000472:pathogenicity; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002151:Calorimetry; D018360:Crystallography, X-Ray; D004777:Environment; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D009005:Monosaccharides / Q000378:metabolism; D016296:Mutagenesis; D010636:Phenols / Q000378:metabolism; D011485:Protein Binding; D013400:Sugar Acids / Q000378:metabolism; D037521:Virulence Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014961:X-Ray Diffraction
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D009005:Monosaccharides; D010636:Phenols; D013400:Sugar Acids; D037521:Virulence Factors