Phenolic/Signal Receptor Interactions in Agrobacterium

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This research will study the mechanism(s) whereby phenolics interact with specific receptors to elicit cellular responses. An important model system that cues on phenolics as signals is Agrobacterium tumefaciens, a pathogenic soil bacterium that causes tumors at wound sites of infected plants. The bacterium can transfer DNA (T-DNA) from its Ti plasmid into plant cells where it is integrated into the nuclear DNA and expressed, ultimately leading to the tumourous growth of the transformed cells. Most of the vir genes of the Ti plasmid that encode the proteins involved in the processing and transfer of the T-DNA are not expressed until the bacterium receives phenolic molecules produced by wounded plant cells. The putative receptor of this signal (VirA) has been identified by genetic means as a 92kDa cytoplasmic membrane localized protein. A model has been proposed for the phenol/receptor protein association and a description of chemical, biochemical and molecular genetic approaches for the characterization of the interaction have been provided. This simple model system should provide insight into the mechanisms of signal transduction mediated by phenolics. %%% With this Chemistry of Life Processes award, the Synthetic Organic Program of the Chemistry Division and the Cellular Biochemistry Program of the Division of Cellular Biosciences will support the research of Dr. David G. Lynn of the Department of Chemistry of the University of Chicago and Dr. Andrew N. Binns of the Department of Biology of the University of Pennsylvania. The major focus of the research is to study the role of phenolics as signal molecules in both eukaryotic and prokaryotic organisms. Important hormones and growth factors in both the Animal and Plant Kingdoms fall within this class of compounds. Using the model system Agrobacterium tumefaciens, the project will probe the mechanism(s) whereby the phenolics interact with specific receptors to elicit cellular responses. The long-range research goals are directed towards understanding plant development.