Poster: Protein turnover
Abs #
815: The Arabidopsis F-Box Proteins EBF1 and 2 Form SCF E3s That Repress Ethylene Action and Promote Growth By Directing EIN3 Degradation.
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Presenter: |
Gagne, Jennifer M, jennifer.m.gagne@alum.dartmouth.org |
Authors | Gagne, Jennifer M (A) Binder, Brad M (B) Smalle, Jan (A) Bleecker, Anthony B (B) Vierstra, Richard D (A) | | Affiliations: |
(A): Department of Genetics, University Of Wisconsin-Madison
(B): Department of Botany, University of Wisconsin-Madison
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The ubiquitination of various intracellular proteins by ubiquitin protein ligases (or E3s) is essential for eukaryotic cellular regulation by allowing selective proteolysis by the 26S proteasome. SCF complexes are one influential E3 class that use F-Box proteins to deliver targets to a core ligase activity provided by the Skp1, Cullin and Rbx1 subunits. Almost 700 F-Box proteins have been identified in Arabidopsis, indicating that the SCF E3s likely play a pervasive role in plant physiology and development. Here, we describe the reverse genetic analysis of two F-Box proteins EBF1 and 2 that work coordinately in SCF complexes to repress ethylene action. Mutations in either gene cause hypersensitivity to exogenous ethylene. EBF1 and 2 interact directly with ETHYLENE INSENSITIVE-3 (EIN3), a transcriptional regulator important for ethylene signaling. Levels of EIN3 are increased in mutants affecting either EBF1 or 2. Double ebf1 ebf2 mutants display a substantial arrest of seedling growth and have elevated EIN3 levels even in the absence of ethylene. Kinetic analysis shows that while EBF1 and EBF2 appear to work together to degrade EIN3 they have different temporal roles. Collectively our results show that SCFEBF1/EBF2-dependent ubiquitination and subsequent removal of EIN3 is critical not only for proper ethylene signaling but also for plant growth and development.
