Uncovering a novel function of the CCR4-NOT complex in phytochrome A-mediated light signalling in plants
Philipp Schwenk,
David J Sheerin,
Jathish Ponnu,
Anne-Marie Staudt,
Klara L Lesch,
Elisabeth Lichtenberg,
Katalin F Medzihradszky,
Ute Hoecker,
Eva Klement,
András Viczián,
Andreas Hiltbrunner
Affiliations
Philipp Schwenk
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
David J Sheerin
Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany
Institute for Plant Sciences and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Cologne, Germany
Anne-Marie Staudt
Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany
Klara L Lesch
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; Internal Medicine IV, Department of Medicine, Medical Center, University of Freiburg, Freiburg, Germany
Elisabeth Lichtenberg
Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany
Katalin F Medzihradszky
Laboratory of Proteomics Research, Biological Research Centre, Szeged, Hungary
Ute Hoecker
Institute for Plant Sciences and Cluster of Excellence on Plant Sciences (CEPLAS), University of Cologne, Cologne, Germany
Eva Klement
Laboratory of Proteomics Research, Biological Research Centre, Szeged, Hungary
Institute of Biology II, Faculty of Biology, University of Freiburg, Freiburg, Germany; Signalling Research Centres BIOSS and CIBSS, University of Freiburg, Freiburg, Germany
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.
