Di 21.06.2022
Biozentrum
Prof. Soppa

New players in archaeal cell division

Prof. Sonja Albers, Universität Freiburg

In archaea two fundamental different cell division systems are found: the FtsZ-based and the ESCRT III-based division machinery. In contrast to bacteria most archaea which employ the FtsZ-based system harbor two instead of one FtsZ homologue. They have been shown to have indeed different functions during cell division in Haloferax volcanii. We have shown that SepF, a homologue from the bacterial SepF, is essential in H. volcanii and anchors FtsZ to the membrane. Further, no homologues of bacterial cell division are present in archaea. Using pulldown experiments, we have now identified a new, essential player in FtsZ-based cell division in archaea. I will discuss the biochemical characterization and the impact of this protein on cell division in H. volcanii.

Di 05.07.2022

Biozentrum

Prof. Böhmer

Plants in the Anthropocene: from climate change to outer space
Prof. Maik Böhmer, Goethe Universität Frankfurt

Di 12.04.2022

Biozentrum

Dr. Fragkostefanakis

Orchestration of plant heat stress response and thermotolerance by transcription factors and splicing regulators
Dr. Sotirios Fragkostefanais, Goethe Universität Frankfurt

Plants are often exposed to heat stress conditions during the warmer period of the year. Their survival depends on the activation of heat stress response, which comprises the induction of hundreds of genes including the essential for thermotolerance, heat shock proteins (HSPs). Heat stress transcription factors (HSFs) are the core regulators of heat stress response. Using tomato as a model, we have characterized four HSFs which control the major phases of the stress response: activation, acclimation and attenuation. In addition to transcription, high temperatures affect the pre-mRNA splicing profile of many genes, including several HSFs. In the case of HsfA2 and HsfA7, alternative splicing leads to the generation of protein isoforms with distinct properties and contribution to stress response, suggesting that next to transcription factors, splicing regulators have an important role in heat stress response. We have identified two plant-specific splicing regulators belonging to the Serine/Arginine-rich protein family, that mediate a major fraction of temperature-sensitive alternative splicing events and consequently thermotolerance. Our results show that the coordinated activity of transcription factors and splicing regulators mediate the plasticity of plants to respond to different stress regimes.

Di 03.05.2022

Biozentrum

Prof. Helfrich

Natural Product Biosynthesis off the Beaten Path: Machine Learning-based Discovery of Non-Canonical Natural Products
Prof. Eric Helfrich, Goethe Universität Frankfurt

Around 50% of all approved drugs over the last 40 years have either been natural products, natural product-derived, or at least inspired by natural products. The pace of the discovery of truly novel bioactive metabolites, however, has slowed down significantly as traditional bioactivity-guided screening approaches frequently result in the rediscovery of known metabolites. To circumvent the rediscovery problem in the post-genomics era, a new approach for the targeted identification of novel natural products has been developed: Genome mining is an in-silico natural product discovery strategy that uses genome sequence information to assess the natural product biosynthetic potential of an organism. Several generations of highly sophisticated genome mining pipelines have been developed identify and annotate of natural product biosynthetic gene clusters and predict the structures of the associated metabolites. These bioinformatic tools are, however, limited when it comes to the identification of biosynthetic gene clusters of natural products that are modified beyond recognition by spontaneous, non-enzymatic transformations or if their biosynthesis deviates significantly from the beaten path. Moreover, current genome mining pipelines cannot predict natural products structures of metabolites associated with poorly studied natural product classes. We are studying these non-canonical biosynthetic pathways and develop machine learning-based genome mining algorithms to chart the biosynthetic dark matter that is currently overlooked by state-of-the-art genome mining platforms. Our studies aim at expanding natural product chemical space and lead to the characterization of cryptic biosynthetic transformations.

Di 17.05.2022

Biozentrum

Dr. Fragkostefanakis

A Role for Plant Linker of Nucleoskeleton and Cytoskeleton (LINC) Complexes in Male Fertility and Drought Response
Prof. Iris Meier, Ohio State University

Unlike usually depicted in text-book figures, the nucleus is not a passive organelle resting at the center of the cell. Nuclei change shape and are actively transported and positioned within the cell. In animals, this is crucial for several developmental processes and physiological situations. Linker of nucleoskeleton and cytoskeleton (LINC) complexes connect the cytoskeleton through the double membranes of the nuclear envelope to the nucleoplasm and are involved in anchoring and moving the nucleus, mechanical signal transduction, nuclear morphology, and chromatin-nuclear envelope association. Plants share the inner nuclear membrane component of LINC complexes with animals and fungi but have acquired during evolution unique outer nuclear envelope components. Arabidopsis LINC complexes are involved in nuclear movement and positioning in several cell types, including pollen tubes, guard cells, and root hairs. A specific plant LINC complex is essential for nuclear migration during pollen tube growth. Loss‐of‐function mutations result in impaired pollen nuclear movement and defects in pollen tube reception and thus ultimately plant male fertility. Another LINC complex modulates stomatal dynamics during abiotic stress, involving calcium signaling and an actin‐remodeling event, relevant for plant drought tolerance.  We are investigating structure-function relationships of plant LINC complexes in these different contexts with a specific focus on plant-unique functions.