Prof. Rüdiger HellMolecular Biology of Plants
The Department of Molecular Biology of Plants investigates the mechanisms of metabolic homeostasis in plants that controls growth in relation to developmental programs and during acclimation to changing environments. To this end, the metabolism of sulfur proved to be highly suitable to study general mechanisms of plant nutrient and water sensing and of growth control at cellular and organismal levels. The second major theme is represented by Dr. Markus Wirtz. It is linked to this concept by investigating cellular proteostasis reactions to stress. In the focus are protein turnover and damage repair via co-translational acetylation of protein N-termini. The department further hosts the Metabolomics Core Technology Platform that provides scientific services for the entire Heidelberg Life Science Campus. Teaching activities of the department include molecular genetics, biochemistry, physiology and biotechnology of model and crop plants.
Plants are photoautotrophic organisms and ultimately the almost exclusive source of sulfur for human and animal life. The regulation of sulfur metabolism is investigated using the favorite plant of molecular biologists, Arabidopsis thaliana. It is a member of the Brassicaceae family to which crop plants such as oil seed rape and cabbage but also spicy food like mustard, radish and rucola belong. The central compound in plant sulfur metabolism is the amino acid cysteine. It is the precursor or sulfur donor for all compounds containing reduced sulfur in the cell. Since cysteine donates reduced sulfur to essential nutrient components such as methionine and some vitamins, it is of great importance for human and animal nutrition. Sulfur is indispensable for proteins (methionine, disulfide bridges), electron transport (Fe/S clusters), redox control (glutathione) and cofactors (acetyl coenzyme A, biotin, thiamine, lipoic acid). In plants it additionally contributes to herbivore defense and specialized metabolism.
The N-terminal acetylation of proteins by N-acetyltransferases (NATs) is the other major topic of the department. N-terminal acetylation is probably the most abundant co-translational modification of eukaryotic proteins, with more than 80% of proteins being fully or partially acetylated in mammals and plants. Recent findings by our department uncovered a broad spectrum of acetylation on metabolic proteins and the presence of a family of similar NAT complexes in Arabidopsis as compared to yeast and mammals. The remarkable evolutionary conservation of the cytosolic N-acetylation machinery enables us to address its mechanism of action using Arabidopsis as an experimental system. On top of the conserved cytosolic ribosome anchored Nat machinery, plants possess a sophisticated system of post-translationally acting NATs in plastids. For more information on plant NATs follow the link to the webpage of Dr. Markus Wirtz on the right side.