title: Mutants of the Agrobacterium tumefaciens virA gene exhibiting acetosyringone-independent expression of the vir regulon.
abstract: Hydroxylamine-induced mutations in the virA gene of Agrobacterium tumefaciens that do not require the plant phenolic-inducing compound acetosyringone for vir regulon induction were isolated. The isolation was based on the activation of both virB::lacZ and virE::cat fusions by mutant virA loci in the absence of acetosyringone. Three of these virA(Ais) (acetosyringone-independent signaling) mutants were characterized. All three mutants expressed a virB::lacZ fusion at high levels in the absence of acetosyringone. One virA (Ais) mutant, virA112, exhibited vir gene expression in the absence of inducing monosaccharides and acidic growth conditions, both of which are normally required for vir gene induction. The phenotype of the virA112 mutant resulted from a glycine to glutamic acid change near His-474, the site of VirA autophosphorylation.
authors.affiliation: Department of Microbiology, University of Washington, Seattle 98195.
authors.forename: R G
authors.initials: RG
authors.lastname: Ankenbauer
authors.forename: E A
authors.initials: EA
authors.lastname: Best
authors.forename: C A
authors.initials: CA
authors.lastname: Palanca
authors.forename: E W
authors.initials: EW
authors.lastname: Nester
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D016960:Agrobacterium tumefaciens / Q000235:genetics*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D004269:DNA, Bacterial; D005798:Genes, Bacterial; D005998:Glycine / Q000737:chemistry; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010766:Phosphorylation; D010957:Plasmids; D037521:Virulence Factors
chemical_list: D000098:Acetophenones; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D037521:Virulence Factors; C051667:acetosyringone; D005998:Glycine