title: Altered-function mutations of the transcriptional regulatory gene virG of Agrobacterium tumefaciens.
abstract: Three point mutations were isolated in the Agrobacterium tumefaciens virG gene by screening for vir gene expression in the absence of added phenolic inducing compounds. All three mutations were localized in the predicted amino-terminal phosphoryl receiver domain of the protein. One mutant (N54D) bypasses the requirement for VirA and phenolic inducers both for transcriptional activation of all tested vir promoters and for plant tumorigenesis. This mutant also activates vir gene expression efficiently at neutral pH, indicating that the step in induction that is normally stimulated by acid pH occurs before or during VirG phosphorylation. The other two mutants (M13T and H15R) require VirA for activity but are sensitized to low levels of inducing stimuli.
authors.affiliation: Section of Microbiology, Cornell University, Ithaca, New York 14853.
authors.forename: D C
authors.initials: DC
authors.lastname: Han
authors.forename: C Y
authors.initials: CY
authors.lastname: Chen
authors.forename: Y F
authors.initials: YF
authors.lastname: Chen
authors.forename: S C
authors.initials: SC
authors.lastname: Winans
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D016960:Agrobacterium tumefaciens / Q000235:genetics* / Q000472:pathogenicity; D001426:Bacterial Proteins / Q000235:genetics*; D004268:DNA-Binding Proteins; D004305:Dose-Response Relationship, Drug; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D016296:Mutagenesis; D010944:Plants / Q000382:microbiology; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000187:drug effects; D014774:Virulence
chemical_list: D000098:Acetophenones; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D014157:Transcription Factors; C058483:virG protein, Shigella flexneri; C051667:acetosyringone