Dynamic Regulation of DELLA Protein Activity: SPINDLY and SECRET AGENT Unmasked!  Lucie Camut, Jean-Michel Davière, Patrick Achard  Molecular Plant  Volume 10, Issue 6, Pages 785-787 (June 2017) DOI: 10.1016/j.molp.2017.05.003 Copyright © 2017 The Author Terms and Conditions

Figure 1 Post-Translational Modifications of DELLAs Allow Dynamic Regulation of Plant Growth. (A) Post-translational modifications of DELLAs are modulated by the convergence of multiple environmental and endogenous signals, which in turn have an impact on their conformation, activity, or stability. The positions of known and potential (highlighted by an asterisk) post-translational modifications are indicated on a schematic representation of a DELLA. Specific sites of ubiquitylation are unknown. The DELLA, KLE, and PolyS/T motifs are indicated. SUMO, SUMOylation; P, phosphorylation; Ub, ubiquitylation; Gly, glycosylation. (B) Overview of the effects of GA, SEC, and SPY on DELLA protein stability and activity. The binding of GA to GID1 stimulates the polyubiquitylation and subsequent degradation of DELLA by the 26S proteasome pathway. The O-fucosyltransferase SPY and O-GlcNAc transferase SEC respectively activate and repress the growth-repressing activity of DELLA through modulation of the DELLA-TF/TR interaction, leading to transcriptional reprogramming, hence ensuring flexible regulation of plant growth. It is suggested that SPY and SEC induce opposite conformational transition of DELLA, which respectively enhances and prevents the binding of DELLA with interacting partners. By doing so, DELLAs regulate the expression of target genes via two mechanisms: protein sequestration and transactivation. +, DELLA acts as transcriptional activator. GID1, GIBBERELLIN-INSENSITIVE DWARF1; SCF, SLEEPY/CULLIN/Fbox E3 ligase complex; TF, transcription factor; TR, transcription regulator; GA, gibberellin. Molecular Plant 2017 10, 785-787DOI: (10.1016/j.molp.2017.05.003) Copyright © 2017 The Author Terms and Conditions