Research - Institute of Plant Biology - Laboratory of Plant Photo- and Chronobiology

Ferenc NAGY
research professor

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László KOZMA-BOGNÁR senior research associate
Éva ÁDÁM senior research associate
András VICZIÁN senior research associate
Anita KOZMA-BOGNÁRNÉ HAJDU research associate
Hedvig KOÓSNÉ MAJZIK scientific administrator
Péter BERNULA junior research associate
Orsolya DOBOS Ph.D. student
Gabriella SZABÓNÉ VERES laboratory assistant
Róbertné HAJÓ laboratory assistant

MOLECULAR MECHANISMS OF LIGHT AND CLOCK-SIGNALING PATHWAYS IN ARABIDOPSIS

Plants are sessile organisms, and to optimize their competitiveness they have to adapt to the ever changing abiotic and biotic environment. From among the numerous abiotic environmental factors light is arguably the most important one for plants, as plants use light not only as the energy source for photosynthesis but also as a developmental clue. To harmonise their growth to changes in the ambient light environment, plants evolved a battery of specialized photoreceptors. These photoreceptors monitor the wavelength, intensity, duration and direction of incipient sunlight and include the UVB-sensing UVR-8, the blue/UVA light absorbing cryptochromes, phototropins and ZTL-like photoreceptors as well as the red/far-red light absorbing phytochromes.

Phytochromes (phy) are chromoproteins; they exist as dimers, and each monomer contains a covalently linked open tetrapyrrol chain chromophore. They cycle between their biologically inactive (Pr, λmax 660 nm) and active (Pfr, λmax 730 nm) forms and act as light quality/quantity dependent molecular switches to control photomorphogenesis. UVR8 is the first known UVB-specific sensor; it exists in its inactive form as a dimer and absorption of UVB induces the monomerisation to launch signaling. The biologically active conformers of both phytochromes and UVR8 accumulate in the nucleus, interact with numerous proteins and regulate, via protein–protein interactions, the expression of hundreds of genes in a wavelength-specific fashion.

The major research interest of our group is to characterise those molecular events that are essential for launching, fine-tuning and terminating phytochrome and UVR8 regulated signalling cascades, ultimately photomorphogenesis. Within this broad topic we are particularly interested in characterising (i) the molecular mechanism by which these photoreceptors mediate light-dependent entrainment of the circadian clock, (ii) the components mediating, in a light-quality-dependent fashion, nucleocytoplasmic partitioning of phytochromes and UVR8, (iii) how phosphorylation and sumoylation of these photorecepors and other signalling components modulate red/far-red and UVB-induced signalling, and (iv) to what extent intercellular and cell-autonomous events contribute to phytochrome and UVR8 regulated photomorphogenesis.

Selected publications

Muller K., Engesser, R., Metzger, S., Schulz, S., Kampf, M-M., Busacker, M., Steinberg, T., Tomakidi, P., Ehrbar, M., Nagy, F., Timmer, J., Zurbriggen, M-D., Weber, W. (2013) A red/far-red light-responsive bi-stable toggle switch to control gene expression in mammalian cell. Nucl. Acid Res. Vol. 41, Issue 7, Pp e77

Medzihradszky, M., Bindics, J., Ádám, E., Viczián, A., Klement, E., Lorrain, S., Gyula, P., Mérai, Z., Fankhauser, C., Medzihradszky, KF., Kunkel, T., Schäfer, E., Nagy, F. (2013) Phosphorylation of Phytochrome B Inhibits Light-Induced Signaling via Accelerated Dark Reversion in Arabidopsis. Plant Cell 2: 535-544

Terecskei, K., Tóth, R., Gyula, P., Kevei, E., Bindics, J., Coupland, G., Nagy, F., Kozma-Bognár, L.(2013) The circadian clock-associated small GTPase LIGHT INSENSITIVE PERIOD1 suppresses light-controlled endoreplication and affects tolerance to salt stress in Arabidopsis. Plant Physiol. 161:278-90.

Pfeiffer, A., Nagel, M-K., Popp, C., Wüst, F., Bindics, J., Viczián, A., Hiltbrunner, A., Nagy, F., Kunkel, T., Schäfer, E. (2012) Interaction with plant transcription factors can mediate nuclear import of phytochrome B. Proc. Natl. Acad. Sci. USA 109:5892-5897

Kolmos, E., Herrero, E., Bujdosó, N., Millar, A., Tóth, R., Gyula, P., Nagy, F., Davis, S. (2011) A reduced-function allele reveals that EARLY FLOWERING3 repressive action on the circadian clock is modulated by phytochrome signals in Arabidopsis. Plant Cell 23: 3230-3246

Rizzini, L., Favoury, J., Cloix, C., Faggionato, D., O’Hara, A., Kaiserli, E., Baumeister, R., Schäfer, E., Nagy, F., Jenkins, G., Ulm, R. (2011) Perception of UV-B by the Arabidopsis UVR8 protein. Science 332: 103-106.

Fehér, B., Kozma-Bognár, L., Kevei, É., Hajdu, A., Binkert, M., Davis, S., Schäfer, E., Ulm, R., Nagy, F. (2011) Functional interaction of the circadian clock and UV RESISTANCE LOCUS-8 controlled signaling pathways in Arabidopsis thaliana. Plant J. 67:37-48.

Palágyi, A., Terecskei, K., Ádám, É., Kevei, É, Kircher, S.,, Mérai, Z., Schäfer, E., Nagy, F., Kozma-Bognár, L. (2010) Functional analysis of amino-terminal domains of the photoreceptor phytochrome B. Plant Phys. 153, 1834-1845.

Edwards, K.D., Akman, O.E., Knox, K., Lumsden, P.J., Thomson, A.W., Brown, P.E., Pokhilko, A., Kozma-Bognár, L., Nagy, F., Rand, D.A., Millar, A.J. (2010) Quantitative analysis of regulatory flexibility under changing environmental conditions. Mol. Syst. Biol. 6:424.

Pfeiffer, A., Kunkel, T., Hiltbrunner, A., Neuhaus, G., Wolf, I., Speth, V., Ádám, É., Nagy, F., Schäfer, E. (2009) A cell-free system for light-dependent nuclear import of phytochrome. Plant J. 57, 680-689

Favory, J-J., Stec, A., Gruber, H., Rizzini, L., Oravecz, A., Funk, M., Albert, A., Cloix, C., Jenkins, G.I., Oakeley, E.J., Seidlitz, H.K., Nagy, F., Ulm, R. (2009) Interaction of COP1 and UVR8 regulates UV-B-induced photomorphogenesis and stress acclimation in Arabidopsis. EMBO J. 28, 591-601.

Sáfrány, J., Haasz, V., Máté, Z., Ciolfi, A., Fehér, B., Oravecz, A., Stec, A., Dallmann, G., Morelli, G., Ulm, R., Nagy, F. (2008) Identification of a novel cis-regulatory element for UV-B induced transcription in Arabidopsis. Plant J. 54, 402-414.