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- Title
The Role of Two F-Box Proteins, SLEEPY1 and SNEEZY, in Arabidopsis Gibberellin Signaling.
- Authors
Ariizumi, Tohru; Lawrence, Paulraj K.; Steber, Camille M.
- Abstract
The SLEEPY1 (SLY1) F-box gene is a positive regulator of gibberellin (GA) signaling in Arabidopsis (Arabidopsis Ihahana). Loss of SLY1 results in GA-insensitive phenotypes including dwarfism, reduced fertility, delayed flowering, increased seed dormancy. These slyl phenotypes are partially rescued by overexpression of the SLY1 homolog SNEEZY (SNE)/SLY2, suggesting that SNE can functionally replace SLY1. GA responses are repressed by DELLA family proteins. GA relieves DELLA repression when the SCFSLY1 (for Skpl, Cullin, F-box) E3 ubiquitin ligase ubiquitinates DELLA protein, thereby targeting it for proteolysis. Coimmunoprecipitation experiments using constitutively expressed 35S:hemagglutinin (HA)-SLYl and 35S:HA-SNE translational fusions in the slyl-10 background! suggest that SNE can function similarly to SLY1 in GA signaling. Like HA-SLY1, HA-SNE interacted with the CULLTN1 subunit of the SCF complex, this interaction required the F-box domain. Like HA-SLY1, HA-SNE coimmunoprecipitated with the DELLA REPRESSOR OF GA1-3 (RGA), this interaction required the SLY1 or SNE carboxyl-terminal domain. Vyhereas HA-SLY1 overexpression resulted in a decrease in both DELLA RGA and RGA-LIKE2 (RGL2) protein levels, HA-SNE: caused a decrease in DELLA RGA but not in RGL2 levels. This suggests that one reason HA-SLY1 is able to effect a stronger rescue of slyl-10 phenotypes than HA-SNE is because SLY1 regulates a broader spectrum of DELLA proteins. The FLAG-SLY1 fusion protein was found to coimmunoprecipitate with the GA receptor HA-GA-INSENSTTIVE DWARFlb (GIDlb), supporting the model that SLY1 regulates DELLA through interaction with the DELLA-GA-GID1 complex.
- Subjects
PROTEINS; ARABIDOPSIS; GIBBERELLINS; PHENOTYPES; PLANT genetics
- Publication
Plant Physiology, 2011, Vol 155, Issue 2, p765
- ISSN
0032-0889
- Publication type
Article
- DOI
10.1104/pp.110.166272