Universität zu Köln 

Prof. Dr. Ute Höcker

Botanisches Institut, Universität zu Köln
email: hoeckeru@uni-koeln.de
phone: +49-(0)221 470 6897
website

The COP1/SPA E3 ubiquitin ligase suppresses light signalling in dark-grown plants by mediating the degradation of transcription factors involved in light signalling. We have shown that the four SPA proteins are essential, plant-specific components of this ubiquitin ligase and, moreover, provide functional specificity. Here, we will analyse 1) the biochemical functions of SPA proteins in the COP1/SPA ubiquitin ligase, 2) the molecular basis for the distinct functions of SPA1 and SPA2, 3) the functions of the particular domains of SPA1 and 4) novel substrates of this ubiquitin ligase. We expect that our analyses will strongly deepen our understanding of function and regulation of this key ubiquitin ligase in light signalling and, moreover, may allow us to understand why SPA proteins are necessary for COP1 function in plants but not in animals.

Running time: 10/2006 – 06/2015

Recent publications:

Ordonez-Herrera, N. Fackendahl, P., Yu, X., Schaefer, S., Koncz, C., and Hoecker, U. (2015). A cop1 spa mutant deficient in COP1 and SPA proteins reveals partial co-action of COP1 and SPA during Arabidopsis post-embryonic development and photomorphogenesis. Mol. Plant 8, 479-481. PubMed

Maier, A. and Hoecker, U. (2014). COP1/SPA ubiquitin ligase complexes repress anthocyanin accumulation under low light and high light conditions. Plant Signaling & Behavior. [Epub ahead of print]

Ranjan, A., Dickopf, S., Ullrich, K.K., Rensing, S.A., Hoecker, U. (2014). Functional analysis of COP1 and SPA orthologs from Physcomitrella and rice during photomorphogenesis of transgenic Arabidopsis reveals distinct evolutionary conservation. BMC Plant Biol. 14:178. PubMed

Schrader, A., Welter, B., Hulskamp, M., Hoecker, U., Uhrig, J.F. (2013). MIDGET connects COP1-dependent development with endoreduplication in Arabidopsis thaliana. Plant J. 75, 67-79. PubMed

Maier, A., Schrader, A., Kokkelink, L., Falke, C., Welter, B., Iniesto, E., Rubio, V., Uhrig, J.F., Hulskamp, M. and Hoecker, U. (2013). Light and the E3 ubiquitin ligase COP1/SPA control the protein stability of the MYB transcription factors PAP1 and PAP2 involved in anthocyanin accumulation in Arabidopsis. Plant J. 74, 638-51. PubMed

Rolauffs, S., Fackendahl, P., Sahm, J., Fiene, G. and Hoecker, U. (2012). Arabidopsis COP1 and SPA genes are essential for plant elongation but not for acceleration of flowering time in response to a low red light to far-red light ratio. Plant Physiol. 160, 2015-27. PubMed

Balcerowicz, M.*, Fittinghoff, K.*, Wirthmueller, L., Maier, A., Fackendahl, P., Fiene, G., Koncz C. and Hoecker, U. (2011). Light-exposure of Arabidopsis seedlings causes rapid de-stabilization as well as selective post-translational inactivation of the repressor of photomorphogenesis SPA2. Plant J. 65, 712-23. (* joint first authorship) PubMed

Nixdorf, M. and Hoecker, U. (2010). SPA1 and DET1 act together to control photomorphogenesis throughout plant development. Planta 231, 825-833.

Sellaro, R., Hoecker, U., Yanovsky, M., Chory, J., and Casal, J.J. (2009). Synergism of red and blue light in the control of Arabidopsis gene expression and development. Curr. Biol. 19, 1216-1220.

Zhu, D., Maier, A., Lee, J.H., Laubinger, S., Saijo, Y., Wang, H., Qu, L.J., Hoecker, U., and Deng, X.W. (2008). Biochemical characterization of Arabidopsis complexes containing CONSTITUTIVELY PHOTOMORPHOGENIC1 and SUPPRESSOR OF PHYA proteins in light control of plant development. Plant Cell 20, 2307-2323.

Fittinghoff, K., Laubinger, S., Nixdorf, M., Fackendahl, P., Baumgardt, R.L., Batschauer, A., and Hoecker, U. (2006). Functional and expression analysis of Arabidopsis SPA genes during seedling photomorphogenesis and adult growth. Plant J. 47, 577-590.

Laubinger, S., Marchal, V., Gentilhomme, J., Wenkel, S., Adrian, J., Jang, S., Kulajta, C., Braun, H., Coupland, G., and Hoecker, U. (2006). Arabidopsis SPA proteins regulate photoperiodic flowering and interact with the floral inducer CONSTANS to regulate its stability. Development 133, 3213-3222.