Schwenk Philipp, Sheerin David J, Ponnu Jathish, Staudt Anne-Marie, Lesch Klara L, Lichtenberg Elisabeth, Medzihradszky Katalin F, Hoecker Ute, Klement Eva, Viczián András, Hiltbrunner Andreas
Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany.
Spemann Graduate School of Biology and Medicine (SGBM), University of Freiburg, Freiburg, Germany.
Elife. 2021 Mar 30;10:e63697. doi: 10.7554/eLife.63697.
Phytochromes are photoreceptors regulating growth and development in plants. Using the model plant Arabidopsis, we identified a novel signalling pathway downstream of the far-red light-sensing phytochrome, phyA, that depends on the highly conserved CCR4-NOT complex. CCR4-NOT is integral to RNA metabolism in yeast and animals, but its function in plants is largely unknown. NOT9B, an Arabidopsis homologue of human CNOT9, is a component of the CCR4-NOT complex, and acts as negative regulator of phyA-specific light signalling when bound to NOT1, the scaffold protein of the complex. Light-activated phyA interacts with and displaces NOT9B from NOT1, suggesting a potential mechanism for light signalling through CCR4-NOT. ARGONAUTE 1 and proteins involved in splicing associate with NOT9B and we show that NOT9B is required for specific phyA-dependent alternative splicing events. Furthermore, association with nuclear localised ARGONAUTE 1 raises the possibility that NOT9B and CCR4-NOT are involved in phyA-modulated gene expression.
光敏色素是调节植物生长发育的光感受器。利用模式植物拟南芥，我们鉴定了远红光感应光敏色素phyA下游的一条新信号通路，该通路依赖于高度保守的CCR4-NOT复合体。CCR4-NOT在酵母和动物的RNA代谢中不可或缺，但其在植物中的功能 largely unknown。NOT9B是人类CNOT9的拟南芥同源物，是CCR4-NOT复合体的一个组成部分，当与复合体的支架蛋白NOT1结合时，作为phyA特异性光信号的负调节因子。光激活的phyA与NOT1相互作用并将NOT9B从NOT1上取代，这表明了通过CCR4-NOT进行光信号传导的潜在机制。AGO1和参与剪接的蛋白质与NOT9B相关联，并且我们表明NOT9B是特定的phyA依赖性可变剪接事件所必需的。此外，与核定位的AGO1的关联增加了NOT9B和CCR4-NOT参与phyA调节的基因表达的可能性。
