Functional roles assigned to the periplasmic, linker, and receiver domains of the Agrobacterium tumefaciens VirA protein.
VirA and VirG activate the Agrobacterium tumefaciens vir regulon in response to phenolic compounds, monosaccharides, and acidity released from plant wound sites. VirA contains an amino-terminal periplasmic domain and three cytoplasmic domains: a linker, a protein kinase, and a phosphoryl receiver. We constructed internal deletions of virA that truncate one or more domains and tested the ability of the resulting proteins to mediate environmentally responsive vir gene activation in vivo. The periplasmic domain is required for sensing of monosaccharides (in agreement with earlier results), while the linker domain is required for sensing of phenolic compounds and acidity. The phosphoryl receiver domain of VirA plays an inhibitory role in signal transduction that may be modulated by phosphorylation. The carboxy terminus of the protein was also dispensable for tumorigenesis, while the periplasmic domain was required.
Chang
C H
CH
Section of Microbiology, Cornell University, Ithaca, New York 14853.
Winans
S C
SC
D016960:Agrobacterium tumefaciens / Q000235:genetics* / Q000472:pathogenicity; D000483:Alleles; D001224:Aspartic Acid; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins; D026901:Membrane Transport Proteins; D008969:Molecular Sequence Data; D016296:Mutagenesis; D033902:Periplasmic Binding Proteins; D010944:Plants / Q000382:microbiology; D017434:Protein Structure, Tertiary; D015398:Signal Transduction / Q000235:genetics; D014157:Transcription Factors; D014774:Virulence; D037521:Virulence Factors
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D026901:Membrane Transport Proteins; D033902:Periplasmic Binding Proteins; D014157:Transcription Factors; D037521:Virulence Factors; C058483:virG protein, Shigella flexneri; D001224:Aspartic Acid