Universität zu Köln 

PD Dr. Seth Davis

Max-Planck-Institut für Pflanzenzüchtungsforschung, Köln
email: davis@mpiz-koeln.mpg.de
phone: +49-(0)221 5062 267
website

The plant circadian clock integrates with light signalling at dawn to mediate clock resetting. This application focuses on post-translational modification of the circadian clock protein TIME FOR COFFEE (TIC) from Arabidopsis thaliana and assesses the consequence of these modifications on light-mediated proteolytic control of core-clock proteins by the proteosome. We have contributed to the identity of the molecular circuitry of the clock, and this included our cloning of the TIC gene. It encodes a large protein of unknown activity required for clock resetting at dawn. To derive a biochemical mechanism of TIC action, our preliminary work revealed that TIC interacts with, and is phosphorylated by, the metabolically activated AKIN10 kinase. Genetically, AKIN10 acts to slow down oscillator speed, and does so in a TIC dependent-manner. Therefore, we hypothesise that energy-derived signals at dawn lead to AKIN10 activation and subsequent phosphorylation of TIC, which drives a clock-resetting mechanism through a post-translational pathway. In support of this, we found that TIC can interact with ubiqutin-proteosome components, and that proteosome mutants have strong clock phenotypes. From this foundation, here we propose to test 1) when during the day AKIN10 kinase phosphorylates TIC, 2) assess the light-dependence of this phosphorylation, 3) test the timing of the epistatic relationship between the AKIN10 kinase and TIC, 4) and examine how the proteasome contributes to TIC-dependent effects on the protein accumulation of core-clock proteins. Taken together, understanding how AKIN10/TIC and the proteosome regulate post-translational stability of clock proteins will explain how light resets the circadian oscillator.

Running time: 07/2011 – 06/2015

Recent publications:

Sanchez-Villarreal, A., Shin, J., Bujdoso, N., Obata, T., Neumann, U., Du, S.X., Ding, Z., Davis, A.M., Shindo, T., Schmelzer, E., Sulpice, R., Nunes-Nesi, A., Stitt, M., Fernie, A.R., Davis, S.J. (2013). TIME FOR COFFEE is an essential component in the maintenance of metabolic homeostasis in Arabidopsis thaliana. Plant J. 76, 188-200. PubMed

Staiger, D., Shin, J., Johansson, M., Davis, S.J. (2013). The circadian clock goes genomic. Genome Biol. 14, 208. PubMed 

Shin, J., Du, S., Bujdoso, N., Hu, Y., Davis, S.J. (2013). Overexpression and loss-of-function at TIME FOR COFFEE results in similar phenotypes in diverse growth and physiological responses. J. Plant Biol. 56, 152-159. doi:10.1007/s12374-013-0091-9

Anwer, M.U. and Davis S.J. (2013). An overview of natural variation studies in the Arabidopsis thaliana circadian clock. Semin. Cell Dev. Biol. 24, 422-429. PubMed

Shin, J.,  Anwer M.U., and Davis S.J. (2013). Phytochrome-Interacting Factors (PIFs) as Bridges between Environmental Signals and the Circadian Clock: Diurnal Regulation of Growth and Development. Mol. Plant 6, 592-5. PubMed

Shin, J., Heidrich, K., Sanchez-Villarreal, A., Parker, J.E., Davis, S.J. (2012). TIME FOR COFFEE represses MYC2 protein accumulation to provide time-of-day regulation of jasmonate signaling. The Plant Cell 24  (6), 2470-248. PubMed

Herrero E., Davis S.J. (2012). Time for a nuclear meeting: protein trafficking and chromatin dynamics intersect in the plant circadian system. Mol Plant. 5, 28-39. PubMed

Kolmos, E., Nowak, M., Werner, M., Fischer, K., Schwarz, G., Mathews, S., Schoof, H., Nagy, F., Bujnicki, J.M., and Davis, S.J. (2009). Integrating ELF4 into the circadian system through combined structural and functional studies. HFSP J. 3, 350-366.