Control of expression of Agrobacterium vir genes by synergistic actions of phenolic signal molecules and monosaccharides.
AUTOR(ES)
Shimoda, N
RESUMO
Most virulence (vir) genes of Agrobacterium tumefaciens that are required for the formation of crown gall tumors are expressed in response to such plant signal molecules as acetosyringone and lignin precursors. The phenolic signals are transduced through a receptor VirA protein in the inner membrane of the bacterial cell. The expression of these genes triggers the transfer of a specific DNA segment, called transferred DNA (T-DNA), from the Ti plasmid to plant cells, and its integration into their nuclear DNA. We show here that a group of aldoses (L-arabinose, D-xylose, D-lyxose, D-glucose, D-mannose, D-idose, D-galactose, and D-talose) can markedly enhance acetosyringone-dependent expression of vir genes when the concentration of acetosyringone is limited (10 microM) but does not enhance the expression of noninducible genes. Likewise, a 2-deoxy-D-glucose, a nonmetabolized sugar, is also effective. When a deletion was introduced into the virA gene in the region encoding the periplasmic portion of the VirA protein, enhancement by glucose disappeared, but vir expression was induced by acetosyringone in this mutant. These results suggest that these sugars directly enhance a signaling process initiated by phenolic inducers that results in an increase in expression of the vir genes.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=54601Documentos Relacionados
- Sugar-mediated induction of Agrobacterium tumefaciens virulence genes: structural specificity and activities of monosaccharides.
- Thiobacillus thiooxidans cell wall amino acids and monosaccharides.
- Complementation analysis of Agrobacterium tumefaciens Ti plasmid virB genes by use of a vir promoter expression vector: virB9, virB10, and virB11 are essential virulence genes.
- Genetic evidence for direct sensing of phenolic compounds by the VirA protein of Agrobacterium tumefaciens.
- Transcriptional regulation of the virA and virG genes of Agrobacterium tumefaciens.