Di 12.04.2022
Biozentrum
Dr. Fragkostefanakis
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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.
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Di 03.05.2022
Biozentrum
Prof. Helfrich
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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.
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Di 17.05.2022
Biozentrum
Dr.
Fragkostefanakis
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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. |
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 |
