DELLA proteins restrain germination and elongation growth in Arabidopsis thaliana COP9 signalosome mutants

作者：Dohmann Esther Mirjam Natascha; Nill Carola; Schwechheimer Claus^*

来源：European Journal of Cell Biology, 2010, 89(2-3): 163-168.

DOI：10.1016/j.ejcb.2009.12.001

• Arabidopsis
• COP9 signalosome
• DELLA protein
• E3 ubiquitin ligase
• Gibberellic acid
• Protein degradation
• Signal transduction

The COP9 signalosome (CSN) is an evolutionarily conserved multiprotein complex with an essential role in the development of higher eukaryotes. CSN deconjugates the ubiquitin-related modifier NEDD8 from the cullin subunit of cullin-RING type E3 ubiquitin ligases (CRLs), and CSN-mediated cullin deneddylation is required for full CRL activity. Although several plant E3 CRL functions have been shown to be compromised in Arabidopsis can mutants, none of these functions have so far been shown to limit growth in these mutants. Here, we examine the role of CSN in the context of the E3 ubiquitin ligase SCF(SLEEPY1) ((SLY1)), which promotes gibberellic acid (GA)-dependent responses in Arabidopsis thaliana. We show that can mutants are impaired in GA- and SCF(SLY1)-dependent germination and elongation growth, and we show that these defects correlate with an accumulation and reduced turnover of an SCF(SLY1)-degradation target, the DELLA protein REPRESSOR-OF-gal-3 (RGA). Genetic interaction studies between can mutants and loss-of-function alleles of RGA and its functional homologue GIBBERELLIC ACID INSENSITIVE (GAI) further reveal that RGA and GAI repress defects of germination in strong can mutants. In addition, we find that these two DELLA proteins are largely responsible for the elongation defects of a weak csn5 mutant allele. We thus conclude that an impairment of SCF(SLY1) is at least in part causative for the germination and elongation defects of can mutants, and suggest that DELLA proteins are major growth repressors in these mutants.

• 出版日期2010-3