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Specific binding of VirG to the vir box requires a C-terminal domain and exhibits a minimum concentration threshold.
Mol Microbiol. 1990 Dec; 4(12):2159-66.MM

Abstract

The positive regulatory protein VirG from the virulence region of the Ti plasmid of Agrobacterium tumefaciens was first demonstrated to possess DNA-binding capabilities using chromatographically purified protein and in vitro assays (Powell et al., 1989). This paper is an extension of that research and presents evidence on the in vivo DNA-binding properties of VirG using a transcription interference assay. VirG protein bound specifically to a 'vir box' response element and repressed transcription of a lacZ reporter gene, but increased transcription in the absence of a vir box. A biphasic response in specific DNA-binding was observed upon increasing virG expression, suggesting that specific binding was co-operatively affected by protein concentration. Certain TrpE'-'VirG hybrid proteins also bound the vir box, but required sequences distal to amino acid Arg-118 of the VirG polypeptide. These data further localize a DNA-binding domain within VirG, and support a modified model for the regulation of virulence genes in which transphosphorylation by the coregulator VirA functions to stabilize specific DNA-binding by low concentrations of VirG, resulting in gene activation. Otherwise, at high concentrations, VirG promotes expression of the virulence regulon without assistance from VirA as was shown previously (Rogowsky et al., 1987).

Authors+Show Affiliations

Department of Plant Pathology, University of California, Davis 95616.No affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

2089226

Citation

Powell, B S., and C I. Kado. "Specific Binding of VirG to the Vir Box Requires a C-terminal Domain and Exhibits a Minimum Concentration Threshold." Molecular Microbiology, vol. 4, no. 12, 1990, pp. 2159-66.
Powell BS, Kado CI. Specific binding of VirG to the vir box requires a C-terminal domain and exhibits a minimum concentration threshold. Mol Microbiol. 1990;4(12):2159-66.
Powell, B. S., & Kado, C. I. (1990). Specific binding of VirG to the vir box requires a C-terminal domain and exhibits a minimum concentration threshold. Molecular Microbiology, 4(12), 2159-66.
Powell BS, Kado CI. Specific Binding of VirG to the Vir Box Requires a C-terminal Domain and Exhibits a Minimum Concentration Threshold. Mol Microbiol. 1990;4(12):2159-66. PubMed PMID: 2089226.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Specific binding of VirG to the vir box requires a C-terminal domain and exhibits a minimum concentration threshold. AU - Powell,B S, AU - Kado,C I, PY - 1990/12/1/pubmed PY - 1990/12/1/medline PY - 1990/12/1/entrez SP - 2159 EP - 66 JF - Molecular microbiology JO - Mol. Microbiol. VL - 4 IS - 12 N2 - The positive regulatory protein VirG from the virulence region of the Ti plasmid of Agrobacterium tumefaciens was first demonstrated to possess DNA-binding capabilities using chromatographically purified protein and in vitro assays (Powell et al., 1989). This paper is an extension of that research and presents evidence on the in vivo DNA-binding properties of VirG using a transcription interference assay. VirG protein bound specifically to a 'vir box' response element and repressed transcription of a lacZ reporter gene, but increased transcription in the absence of a vir box. A biphasic response in specific DNA-binding was observed upon increasing virG expression, suggesting that specific binding was co-operatively affected by protein concentration. Certain TrpE'-'VirG hybrid proteins also bound the vir box, but required sequences distal to amino acid Arg-118 of the VirG polypeptide. These data further localize a DNA-binding domain within VirG, and support a modified model for the regulation of virulence genes in which transphosphorylation by the coregulator VirA functions to stabilize specific DNA-binding by low concentrations of VirG, resulting in gene activation. Otherwise, at high concentrations, VirG promotes expression of the virulence regulon without assistance from VirA as was shown previously (Rogowsky et al., 1987). SN - 0950-382X UR - https://www.unboundmedicine.com/medline/citation/2089226/Specific_binding_of_VirG_to_the_vir_box_requires_a_C_terminal_domain_and_exhibits_a_minimum_concentration_threshold_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0950-382X&date=1990&volume=4&issue=12&spage=2159 DB - PRIME DP - Unbound Medicine ER -