Document Detail

Constitutive mutations of Agrobacterium tumefaciens transcriptional activator virG.
MedLine Citation:
PMID:  1597431     Owner:  NLM     Status:  MEDLINE    
The virulence (vir) genes of Agrobacterium tumefaciens Ti plasmids are positively regulated by virG in conjunction with virA and plant-derived inducing molecules. A procedure that utilizes both genetic selection and a genetic screen was developed to isolate mutations in virG that led to elevated levels of vir gene expression in the absence of virA and plant phenolic inducers. Mutants were isolated at a frequency of 1 in 10(7) to 10(8). Substitution mutations at two positions in the virG coding region were found to result in the desired phenotype. One mutant had an asparagine-to-aspartic acid substitution at residue 54, and the other contained an isoleucine-to-leucine substitution at residue 106. In both cases, the mutant phenotype required the presence of the active-site aspartic acid residue at position 52. Further analysis showed that no other substitution at residue 54 resulted in a constitutive phenotype. In contrast, several substitutions at residue 106 led to a constitutive phenotype. The possible roles of the residues at positions 54 and 106 in VirG function are discussed.
G J Pazour; C N Ta; A Das
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of bacteriology     Volume:  174     ISSN:  0021-9193     ISO Abbreviation:  J. Bacteriol.     Publication Date:  1992 Jun 
Date Detail:
Created Date:  1992-07-07     Completed Date:  1992-07-07     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2985120R     Medline TA:  J Bacteriol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  4169-74     Citation Subset:  IM    
Department of Biochemistry, University of Minnesota, St. Paul 55108.
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MeSH Terms
Acetophenones / pharmacology
Bacterial Proteins / genetics*
Base Sequence
Binding Sites / genetics
DNA-Binding Proteins*
Gene Expression Regulation, Bacterial / drug effects,  genetics*
Hydrogen-Ion Concentration
Molecular Sequence Data
Mutagenesis, Site-Directed
Mutation / genetics
Plasmids / genetics
Recombinant Fusion Proteins / genetics
Rhizobium radiobacter / genetics*
Transcription Factors*
Virulence / genetics*
Virulence Factors*
Grant Support
Reg. No./Substance:
0/Acetophenones; 0/Bacterial Proteins; 0/DNA-Binding Proteins; 0/Recombinant Fusion Proteins; 0/Transcription Factors; 0/Virulence Factors; 0/virG protein, Shigella flexneri; 2478-38-8/acetosyringone

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