TY - JOUR T1 - CUL4 forms an E3 ligase with COP1 and SPA to promote light-induced degradation of PIF1 JF - Nature Communications Y1 - 2015 A1 - Zhu, Ling A1 - Bu, Qingyun A1 - Xu, Xiaosa A1 - Paik, Inyup A1 - Hunag, Xi A1 - Hoecker, Ute A1 - Deng, Xing Wang A1 - Huq, Enamul AB -

Plants undergo contrasting developmental programs in dark and light. Photomorphogenesis, a light-adapted programme is repressed in the dark by the synergistic actions of CUL4COP1–SPA E3 ubiquitin ligase and a subset of basic helix-loop-helix transcription factors called phytochrome interacting factors (PIFs). To promote photomorphogenesis, light activates the phytochrome family of sensory photoreceptors, which inhibits these repressors by poorly understood mechanisms. Here, we show that the CUL4COP1–SPA E3 ubiquitin ligase is necessary for the light-induced degradation of PIF1 in Arabidopsis. The light-induced ubiquitylation and subsequent degradation of PIF1 is reduced in the cop1, spaQ and cul4 backgrounds. COP1, SPA1 and CUL4 preferentially form complexes with the phosphorylated forms of PIF1 in response to light. The cop1 and spaQ seeds display strong hyposensitive response to far-red light-mediated seed germination and light-regulated gene expression. These data show a mechanism by which an E3 ligase attenuates its activity by degrading its cofactor in response to light.

VL - 6 ER -