SINAT E3 Ligases Control the Light-Mediated Stability of the Brassinosteroid-Activated Transcription Factor BES1 in Arabidopsis

Publication date: 10 April 2017
Source:Developmental Cell, Volume 41, Issue 1
Author(s): Mengran Yang, Chengxiang Li, Zhenying Cai, Yinmeng Hu, Trevor Nolan, Feifei Yu, Yanhai Yin, Qi Xie, Guiliang Tang, Xuelu Wang
The plant hormones brassinosteroids (BRs) participate in light-mediated regulation of plant growth, although the underlying mechanisms are far from being fully understood. In addition, the function of the core transcription factor in the BR signaling pathway, BRI1-EMS-SUPPRESSOR 1 (BES1), largely depends on its phosphorylation status and its protein stability, but the regulation of BES1 is not well understood. Here, we report that SINA of Arabidopsis thaliana (SINATs) specifically interact with dephosphorylated BES1 and mediate its ubiquitination and degradation. Our genetic data demonstrated that SINATs inhibit BR signaling in a BES1-dependent manner. Interestingly, we found that the protein levels of SINATs were decreased in the dark and increased in the light, which changed BES1 protein levels accordingly. Thus, our study not only uncovered a new mechanism of BES1 degradation but also provides significant insights into how light conditionally regulates plant growth through controlling accumulation of different forms of BES1.

Teaser

The function of BES1 largely depends on its phosphorylation status and protein stability. Yang et al. show that SINAT E3 ligases specifically mediate degradation of dephosphorylated BES1, and light can stabilize SINAT proteins to regulate BES1 level. Therefore, the SINATs-BES1 module links light and BR signaling to regulate plant development.


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