E3 SUMO ligase AtSIZ1 positively regulates SLY1-mediated GA signalling and plant development

Abstract

Gibberellins affect various plant development processes including germination, cell division and elongation, and flowering. A large number of studies have been carried out to address the molecular mechanisms that mediate gibberellin signalling effects on plant growth. However, such studies have been limited to DELLA protein degradation; the regulatory mechanisms controlling how the stability and function of SLEEPY1 (SLY1), a protein that interacts with target DELLA proteins as components of the Skp, Cullin, F-box (SCF)(SLY1) complex, are modulated at the post-translational level have not been addressed. In the present study, we show that the E3 SUMO (small ubiquitin-related modifier) ligase AtSIZ1 regulates gibberellic acid signalling in Arabidopsis species by sumoylating SLY1. SLY1 was less abundant in siz1-2 mutants than in wild-type plants, but the DELLA protein repressor of ga1-3 (RGA) was more abundant in siz1-2 mutants than in wild-type plants. SLY1 also accumulated to a high level in the SUMO protease mutant esd4. Transgenic sly1-13 mutants over-expressing SLY1 were phenotypically similar to wild-type plants; however, sly1-13 plants over-expressing a mutated mSLY1 protein (K122R, a mutation at the sumoylation site) retained the mutant dwarfing phenotype. Over-expression of SLY1 in sly1-13 mutants resulted in a return of RGA levels to wild-type levels, but RGA accumulated to high levels in mutants over-expressing mSLY1. RGA was clearly detected in Arabidopsis co-expressing AtSIZ1 and mSLY1, but not in plants co-expressing AtSIZ1 and SLY1. In addition, sumoylated SLY1 interacted with RGA and SLY1 sumoylation was significantly increased by GA. Taken together, our results indicate that, in Arabidopsis, AtSIZ1 positively controls GA signalling through SLY1 sumoylation.

SUMO E3 Ligases GmSIZ1a and GmSIZ1b regulate vegetative growth in soybean

“…SUMOylation has been implicated in the regulation of developmental, hormonal, and environmental responses in Arabidopsis , such as gametophyte development (Ling et al ; Liu et al ), embryogenesis (Saracco et al ), photomorphogenesis (Sadanandom et al ; Lin et al ), flowering time (Murtas et al ; Jin et al ), cell proliferation (Huang et al ; Ishida et al ), abscisic acid (ABA) signaling (Miura et al ; Zheng et al ), gibberellic acid (GA) signaling (Kim et al ), the salt stress response (Conti et al ), thermal adaptation (Yoo et al ; Miura et al ), the drought stress response (Catala et al ; Zhang et al ), immune responses (Lee et al ; Saleh et al ), and nutrient (phosphate and nitrogen) starvation signaling (Miura et al ; Park et al ). The SUMO regulatory mechanism is conserved in Oryza sativa (rice), Zea mays (maize), Dendrobium (orchids), and Malus domestica (apple; Park et al ; Liu et al ; Augustine et al ; Zhang et al ).…”

Post‐translational modifications of Arabidopsis E3 SUMO ligase AtSIZ1 are controlled by environmental conditions

“…SAF‐A/B‐Acinus‐PIAS (SAP)and Miz‐finger domain‐containing protein 1 (SIZ1) is an E3 SUMO ligase that has a RING‐like domain, Siz‐PIAS RING (SP‐RING), and a chromatin organization domain, SAP . Arabidopsis E3 SUMO ligase is involved in several developmental processes including germination, nutrient assimilation, hormone signaling, and flowering . In addition, plant E3 SUMO ligases have important roles in the responses to abiotic stresses such as low temperature, drought, heat, and high salt .…”

SUMO proteases OTS1 and 2 control filament elongation through a DELLA-dependent mechanism

“…Besides regulating different steps of GA signalling (Conti et al 2014;Kim et al 2015), SUMOylation controls several responses towards abiotic stress, which usually negatively impact on fertility (Lois et al 2003;Miura et al 2007;Su et al 2013). Thus, a detailed comprehension of the mechanisms underlying reproductive organs differentiation is required to improve crop yield under different environmental conditions.…”