Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Seit Februar 2021 bietet Wolfgang Brandt, ehemaliger Leiter der Arbeitsgruppe Computerchemie am IPB, sein Citizen Science-Projekt zur Pilzbestimmung an. Dafür hat er in regelmäßigen Abständen öffentliche Vorträge zur Vielfalt…
Polko, J. K.; Barnes, W. J.; Voiniciuc, C.; Doctor, S.; Steinwand, B.; Hill, J. L.; Tien, M.; Pauly, M.; Anderson, C. T.; Kieber, J. J.;SHOU4 Proteins Regulate Trafficking of Cellulose Synthase Complexes to the Plasma MembraneCurr. Biol.283174-3182.e6(2018)DOI: 10.1016/j.cub.2018.07.076
Cell walls play critical roles in plants, regulating tissue mechanics, defining the extent and orientation of cell expansion, and providing a physical barrier against pathogen attack [1]. Cellulose microfibrils, which are synthesized by plasma membrane-localized cellulose synthase (CESA) complexes, are the primary load-bearing elements of plant cell walls [2]. Cell walls are dynamic structures that are regulated in part by cell wall integrity (CWI)-monitoring systems that feed back to modulate wall properties and the synthesis of new wall components [3]. Several receptor-like kinases have been implicated as sensors of CWI [3, 4, 5], including the FEI1/FEI2 receptor-like kinases [4]. Here, we characterize two genes encoding novel plant-specific plasma membrane proteins (SHOU4 and SHOU4L) that were identified in a suppressor screen of the cellulose-deficient fei1 fei2 mutant. shou4 shou4l double mutants display phenotypes consistent with elevated levels of cellulose, and elevated levels of non-crystalline cellulose are present in this mutant. Disruption of SHOU4 and SHOU4L increases the abundance of CESA proteins at the plasma membrane as a result of enhanced exocytosis. The SHOU4/4L N-terminal cytosolic domains directly interact with CESAs. Our results suggest that the SHOU4 proteins regulate cellulose synthesis in plants by influencing the trafficking of CESA complexes to the cell surface.
Publikation
Ibañez, C.; Delker, C.; Martinez, C.; Bürstenbinder, K.; Janitza, P.; Lippmann, R.; Ludwig, W.; Sun, H.; James, G. V.; Klecker, M.; Grossjohann, A.; Schneeberger, K.; Prat, S.; Quint, M.;Brassinosteroids Dominate Hormonal Regulation of Plant Thermomorphogenesis via BZR1Curr. Biol.28303-310.e3(2018)DOI: 10.1016/j.cub.2017.11.077
Thermomorphogenesis is defined as the suite of morphological changes that together are likely to contribute to adaptive growth acclimation to usually elevated ambient temperature [1, 2]. While many details of warmth-induced signal transduction are still elusive, parallels to light signaling recently became obvious (reviewed in [3]). It involves photoreceptors that can also sense changes in ambient temperature [3, 4, 5] and act, for example, by repressing protein activity of the central integrator of temperature information PHYTOCHROME-INTERACTING FACTOR 4 (PIF4 [6]). In addition, PIF4 transcript accumulation is tightly controlled by the evening complex member EARLY FLOWERING 3 [7, 8]. According to the current understanding, PIF4 activates growth-promoting genes directly but also via inducing auxin biosynthesis and signaling, resulting in cell elongation. Based on a mutagenesis screen in the model plant Arabidopsis thaliana for mutants with defects in temperature-induced hypocotyl elongation, we show here that both PIF4 and auxin function depend on brassinosteroids. Genetic and pharmacological analyses place brassinosteroids downstream of PIF4 and auxin. We found that brassinosteroids act via the transcription factor BRASSINAZOLE RESISTANT 1 (BZR1), which accumulates in the nucleus at high temperature, where it induces expression of growth-promoting genes. Furthermore, we show that at elevated temperature BZR1 binds to the promoter of PIF4, inducing its expression. These findings suggest that BZR1 functions in an amplifying feedforward loop involved in PIF4 activation. Although numerous negative regulators of PIF4 have been described, we identify BZR1 here as a true temperature-dependent positive regulator of PIF4, acting as a major growth coordinator.
Publikation
Antolín-Llovera, M.; Ried, M. K.; Parniske, M.;Cleavage of the SYMBIOSIS RECEPTOR-LIKE KINASE Ectodomain Promotes Complex Formation with Nod Factor Receptor 5Curr. Biol.24422-427(2014)DOI: 10.1016/j.cub.2013.12.053
Plants form root symbioses with fungi and bacteria to improve their nutrient supply. SYMBIOSIS RECEPTOR-LIKE KINASE (SYMRK) is required for phosphate-acquiring arbuscular mycorrhiza, as well as for the nitrogen-fixing root nodule symbiosis of legumes [1] and actinorhizal plants [2, 3], but its precise function was completely unclear. Here we show that the extracytoplasmic region of SYMRK, which comprises three leucine-rich repeats (LRRs) and a malectin-like domain (MLD) related to a carbohydrate-binding protein from Xenopus laevis [4], is cleaved to release the MLD in the absence of symbiotic stimulation. A conserved sequence motif—GDPC—that connects the MLD to the LRRs is required for MLD release. We discovered that Nod factor receptor 5 (NFR5) [5, 6, 7, 8] forms a complex with the SYMRK version that remains after MLD release (SYMRK-ΔMLD). SYMRK-ΔMLD outcompeted full-length SYMRK for NFR5 interaction, indicating that the MLD negatively interferes with complex formation. SYMRK-ΔMLD is present at lower amounts than MLD, suggesting rapid degradation after MLD release. A deletion of the entire extracytoplasmic region increased protein abundance, suggesting that the LRR region promotes degradation. Curiously, this deletion led to excessive infection thread formation, highlighting the importance of fine-tuned regulation of SYMRK by its ectodomain.
Publikation
Doering, M.; Ba, L. A.; Lilienthal, N.; Nicco, C.; Scherer, C.; Abbas, M.; Zada, A. A. P.; Coriat, R.; Burkholz, T.; Wessjohann, L.; Diederich, M.; Batteux, F.; Herling, M.; Jacob, C.;Synthesis and Selective Anticancer Activity of Organochalcogen Based Redox CatalystsJ. Med. Chem.536954-6963(2010)DOI: 10.1021/jm100576z
Many tumor cells exhibit a disturbed intracellular redox state resulting in higher levels of reactive oxygen species (ROS). As these contribute to tumor initiation and sustenance, catalytic redox agents combining significant activity with substrate specificity promise high activity and selectivity against oxidatively stressed malignant cells. We describe here the design and synthesis of novel organochalcogen based redox sensor/effector catalysts. Their selective anticancer activity at submicromolar and low micromolar concentrations was established here in a range of tumor entities in various biological systems including cell lines, primary tumor cell cultures, and animal models. In the B-cell derived chronic lymphocytic leukemia (CLL), for instance, such compounds preferentially induce apoptosis in the cancer cells while peripheral blood mononuclear cells (PBMC) from healthy donors and the subset of normal B-cells remain largely unaffected. In support of the concept of sensor/effector based ROS amplification, we are able to demonstrate that underlying this selective activity against CLL cells are pre-existing elevated ROS levels in the leukemic cells compared to their nonmalignant counterparts. Furthermore, the catalysts act in concert with certain chemotherapeutic drugs in several carcinoma cell lines to decrease cell proliferation while showing no such interactions in normal cells. Overall, the high efficacy and selectivity of (redox) catalytic sensor/effector compounds warrant further, extensive testing toward transfer into the clinical arena.