Protein Modification and Turnover
St. Pierre, Benoit , Argueso, Cristiana , Heim, John , Matthews, Dwight E. , Delaney, Terrence P. .
Analysis of the Arabidopsis thaliana SON1 F-Box Protein and Putative Substrates.
The arabidopsis SON1 gene was discovered as a genetic suppressor mutation that restored disease resistance in systemic acquired resistance (SAR)-deficient nim1-1 plants. In that work, son1 nim1-1 plants were found to express a novel form of disease resistance, and the SON1 gene to encode a putative F-box protein (Kim and Delaney, Plant Cell 14, 1469). Subsequent genetic and physiological tests showed that salicylate, jasmonate, and ethylene signaling pathways were not required for son1-mediated disease resistance. Because SON1 is an F-box-containing protein, we predict that it functions as part of an E3-ubiquitin ligase SCF complex to regulate disease resistance. To identify candidate SON1-substrate proteins, we used GST-SON1 fusion proteins to isolate binding proteins from arabidopsis extracts. The major protein recovered was purified and rigorously identified using mass spectroscopy analysis. The putative substrate proteinís interaction with SON1 was confirmed using an in vitro translated epitope-tagged version of the candidate protein. We are further analyzing this interaction by identifying the respective domains from each protein that are involved in their binding. Other tests are underway to assess the biological significance of this interaction and its connection to the disease resistance phenotype of son1 mutant plants. In other work, SON1::GUS and SON1-mGFP5 transgenic plants have been created to determine the tissue-distribution and sub-cellular localization of SON1, respectively. Together, this analysis should provide a fuller understanding of SON1 function, and help illuminate its cellular and molecular role(s) in regulating the novel disease-resistance phenotype observed in son1 mutant plants.
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1 - The University of Vermont, Department of Plant Biology
2 - The University of North Carolina, Chapel Hill, Department of Biology
3 - The University of Vermont, Department of Chemistry
4 - The University of Vermont, Department of Plant Biology, Marsh Life Science Building, Burlington, VT, 05405, USA
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM