Photoreceptor-mediated inactivation of the COP1/SPA ubiquitin ligase during Arabidopsis light signal transduction

This project will be supervised by Ute Höcker at the University of Cologne

Abstract:

To sense the light, plants have evolved photoreceptors which include the red/far-red-sensing phytochromes and the blue light-responsive cryptochromes. In Arabidopsis, these photoreceptors inhibit the CONSTITUTIVELY PHOTOMORPHOGENIC1/SUPPRESSOR OF PHYTOCHROME A-105 (COP1/SPA) E3 ubiquitin ligase to allow photomorphogenesis to proceed (Ponnu and Hoecker, Front. Plant Sci, 2021; Ponnu et al., PNAS, 2019). This PhD project will reveal molecular mechanisms on how photoreceptors inhibit the COP1/SPA ubiquitin ligase. In particular, we will investigate how phytochromes inactivate COP1/SPA through high-end analyses of protein-protein interactions in vitro and in vivo combined with genetic tools using mutants and transgenic plants.

Group homepage: https://ag-hoecker.botanik.uni-koeln.de/

Key publication: Ponnu J, Riedel T, Penner E., Schrader A, Hoecker U. (2019). Cryptochrome 2 competes with COP1-substrates to repress COP1 ubiquitin ligase activity during Arabidopsis photomorphogenesis.  Proc. Natl. Acad. Sci. USA, 116: 27133-41. https://doi.org/10.1073/pnas.1909181116