A phyB-PIF1-SPA1 kinase regulatory complex promotes photomorphogenesis in Arabidopsis

作者：Inyup Paik, Fulu Chen, Vinh Ngoc Pham, Ling Q. Zhu, Jeong‐Il Kim, Enamul Huq · 发表于：Nature Communications · 年份：2019 · DOI：10.1038/s41467-019-12110-y · 被引用次数：113 · 研究领域：Light effects on plants、Plant Molecular Biology Research、Photosynthetic Processes and Mechanisms

CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1) is a highly conserved E3 ubiquitin ligase from plants to animals and acts as a central repressor of photomorphogenesis in plants. SUPPRESSOR OF PHYA-105 1 family members (SPA1-SPA4) directly interact with COP1 and enhance COP1 activity. Despite the presence of a kinase domain at the N-terminus, no COP1-independent role of SPA proteins has been reported. Here we show that SPA1 acts as a serine/threonine kinase and directly phosphorylates PIF1 in vitro and in vivo. SPAs are necessary for the light-induced phosphorylation, ubiquitination and subsequent degradation of PIF1. Moreover, the red/far-red light photoreceptor phyB interacts with SPA1 through its C-terminus and enhances the recruitment of PIF1 for phosphorylation. These data provide a mechanistic view on how the COP1-SPA complexes serve as an example of a cognate kinase-E3 ligase complex that selectively triggers rapid phosphorylation and removal of its substrates, and how phyB modulates this process to promote photomorphogenesis.