The main area of research is photobiology, in particular the impact of blue light on plants physiology. Our studies concentrate on phototropins. These UVA/blue light photoreceptors mediate processes which fine tune photosynthesis, including chloroplast movements, phototropism, stomatal opening, leaf positioning and blade formation. Phototropins contain two flavin mononucleotides as chromophores in the photo-sensory LOV (Light, Oxygen and Voltage) domains at the N-terminus and a Ser/Thr kinase domain at the C-terminus. Two phototropins (phototropin1 and phototropin2) are encoded in the genome of the model plant Arabidopsis thaliana. They share highly redundant functions, however some processes are controlled solely by one phototropin. Chloroplast movements in response to light depend on light intensity. Low light induces the chloroplast accumulation response, which is controlled by both phototropin1 and phototropin2. High light induces chloroplast avoidance. Only phototropin2 can trigger full avoidance.

 

 

 

 

 

 

 

 

Phototropin1 can elicit only a residual avoidance response. Thus, phototropins can change their signaling outcomes according to the light intensity. Light down-regulates the level of phototropin1, while it up-regulates the phototropin2 level. Phototropins can form homo- and heterodimers. Dimerization seems to modify their signaling outcomes. The physiological importance of the regulation of phototropin expression and activity is still poorly understood. The molecular basis for the difference in the signaling pathways leading to chloroplast movements in low and high light remains unknown. Differences in the structures of phototropin1 and phototropin2 may determine their ability of changing the pathways from chloroplast accumulation into avoidance. Downstream signaling components: proteins phosphorylated by phototropins or secondary messengers such as phosphoinositides may also be responsible for the modulation of chloroplast responses to light. Currently we focus on the mechanisms through which light controls phototropin expression and activity in Arabidopsis thaliana. We work on molecular aspects of photoreceptor functioning to determine how phototropins control chloroplast movements. Another area of our research is devoted to post–translational modifications (sumoylation, ubiquitination, phosphorylation) of these photoreceptors. We also investigate ecologically relevant aspects of chloroplast movements, such as the impact of UV-B radiation.

 

 

 

 

 

 

 

 

 

The second topic investigated by our group is regulation of plant functioning by UVA/blue light and the properties of plant photolyases. Photolyases are enzymes involved in the direct repair of UVB-induced pyrimidine dimers in a blue light/UVA-dependent manner. This reaction is called photoreactivation. We study the subcellular localization of both well-known and putative Arabidopsis photolyases using proteins fused to fluorescent proteins. We also analyze the effects of visible and UV light on photolyase expression and activity.

 

 

 

 

 

 

 

 

The third area of research is devoted to development of software tools for Atomic Force Microscopy (AFM). AtomicJ, created and still actively developed by P. Hermanowicz, is an application for analysis of images and force - distance curves recorded with AFM. It allows for parallel processing of force – volume measurements, generating maps of mechanical properties of the sample, in particular maps of Young’s modulus, adhesion force, transition indentation, sample height and the deformation. AtomicJ supports several models of contact between the AFM tip and the sample, including models suitable for blunt tips and thin samples, models of adhesive contact and models for hyperelastic materials. Together with the source code, AtomicJ is distributed through SourceForge, under the GPL licence.

•    Łabuz J*, Sztatelman O*, Jagiełło-Flasińska D, Hermanowicz P, Bażant A, Banaś AK, Bartnicki F, Giza A, Kozłowska A, Lasok H, Krzeszowiec-Jeleń W, Gabryś H, Strzałka W. Phototropin interactions with SUMO proteins, Plant and Cell Physiology 2021 https://doi.org/10.1093/pcp/pcab027
•    Eckstein A, Grzyb J, Hermanowicz P, Zgłobicki P, Łabuz J, Strzałka W, Dziga D, Banaś AK. Arabidopsis phototropins participate in the regulation of dark-induced leaf senescence, International Journal of Molecular Sciences 22, 1836.
•    Hermanowicz P, Banaś AK,. Sztatelman O, Gabryś H, Łabuz J. 2019. UV-B Induces Chloroplast Movements in a Phototropin-Dependent Manner. Frontiers in Plant Science, 10, 1279.
•    Eckstein A, Grzyb J, Hermanowicz P, Łabuz J, Banaś AK. 2019. A role for GLABRA1 in dark-induced senescence. Acta Biochimica Polonica, 66, 243–248.
•    Hart JE, Sullivan S, Hermanowicz P, Petersen J, Diaz-Ramos LA, Hoey DJ, Łabuz J, Christie JM. 2019. Engineering the phototropin photocycle improves photoreceptor performance and plant biomass production. PNAS, 116, 12550-12557.
•    Robson TM, Aphalo PJ, Banaś AK, Barnes PW, Brelsford CC, Jenkins GI, Kotilainen TK, Łabuz J, Martínez-Abaigar J, Morales LO, Neugart S, Pieristè M, Rai N, Vandenbussche F, Jansen MAK. 2019. A perspective on ecologically relevant plant-UV research and its practical application. Photochemical and Photobiological Sciences, 18, 970-988.
•    Kowalska E, Bartnicki F, Fujisawa R, Bonarek P, Hermanowicz P, Tsurimoto T, Muszynska K, Strzalka W. 2018. Inhibition of DNA replication by an anti-PCNA aptamer/PCNA complex. Nucleic Acids Research, 46, 25-41.
•    Grzyb J, Gieczewska K, Łabuz J, Sztatelman O. 2018. Detailed characterization of Synechocystis PCC 6803 ferredoxin:NADP+ oxidoreductase interaction with model membranes. Biochimica et Biophysica Acta (BBA) – Biomembranes, 1860, 281-291.
•    Banaś AK, Hermanowicz P, Sztatelman O, Łabuz J, Aggarwal Ch, Zgłobicki P, Jagiełło-Flasińska D, Strzałka W. 2018. 6,4 - PP Photolyase Encoded by AtUVR3 is Localized in Nuclei, Chloroplasts and Mitochondria and Its Expression is Down-Regulated by Light in a Photosynthesis-Dependent Manner. Plant and Cell Physiology, 59, 44–57.
•    Gabryś H, Banaś AK, Hermanowicz P, Krzeszowiec W, Leśniewski S, Łabuz J, Sztatelman O. 2017. Photometric Assays for Chloroplast Movement Responses to Blue Light. Bio-protocol, 7:e2310.
•    Sztatelman O, Łabuz J, Hermanowicz P, Banaś AK, Bażant A, Zgłobicki P, Aggarwal C, Nadzieja M, Krzeszowiec W, Strzałka W, Gabryś H 2016. Fine tuning chloroplast movements through physical interactions between phototropins. Journal of Experimental Botany, 67, 4963-4978.
•    Łabuz J, Samardakiewicz S, Hermanowicz P, Wyroba E, Pilarska M, Gabryś H 2016. Blue light-dependent changes in loosely bound calcium in Arabidopsis mesophyll cells: an X-ray microanalysis study. Journal of Experimental Botany, 67, 3953-3964.