The VirA protein of Agrobacterium tumefaciens is autophosphorylated and is essential for vir gene regulation
- Univ. of Washington, Seattle (USA)
The virA and virG gene products are required for the regulation of the vir regulon on the tumor-inducing (Ti) plasmid of Agrobacterium tumefaciens. VirA is a membrane-associated protein which is homologous to the sensor molecules of other two-component regulatory systems. The authors overproduced truncated VirA proteins in Escherichia coli be deleting different lengths of the 5{prime}-coding region of the virA gene and placing these genes under lacZ control. These proteins were purified from polyacrylamide gels and renatured. The renatured proteins became radiolabeled when they were incubated with ({gamma}-{sup 32}P)ATP but not with ({gamma}-{sup 32}P)GTP or ({alpha}-{sup 32}P)ATP, which suggests an ATP {gamma}-phosphate-specific autophosphorylation. The smallest VirA protein, which retained only the C-terminal half of the protein, gave the strongest autophosphorylation signal, which demonstrates that the C-terminal domain has the autophosphorylation site. The phosphorylated amino acid was identified as phosphohistidine, and a highly conserved histidine was found in all of the VirA homologs. When this histidine was changed to glutamine, which cannot be phosphorylated, the resulting VirA protein lost both its ability to autophosphorylate and its biological function as a vir gene regulator. Results of this study indicate that VirA autophosphorylation is required for the induction of the vir regulon and subsequent tumor induction on plants by A. tumefaciens.
- OSTI ID:
- 7016239
- Journal Information:
- Journal of Bacteriology; (USA), Journal Name: Journal of Bacteriology; (USA) Vol. 172:2; ISSN JOBAA; ISSN 0021-9193
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ATP
AZOLES
BACTERIA
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
CELL CONSTITUENTS
CHEMICAL REACTIONS
DAYS LIVING RADIOISOTOPES
DISEASES
ESCHERICHIA COLI
GENE REGULATION
GENES
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HISTIDINE
IMIDAZOLES
ISOTOPES
LIGHT NUCLEI
MICROORGANISMS
NEOPLASMS
NUCLEI
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PATHOGENS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORYLATION
PLANTS
PLASMIDS
RADIOISOTOPES
TRANSCRIPTION