@article{EderHollmannMandasarietal.2022, author = {Eder, Sascha and Hollmann, Claudia and Mandasari, Putri and Wittmann, Pia and Schumacher, Fabian and Kleuser, Burkhard and Fink, Julian and Seibel, J{\"u}rgen and Schneider-Schaulies, J{\"u}rgen and Stigloher, Christian and Beyersdorf, Niklas and Dembski, Sofia}, title = {Synthesis and characterization of ceramide-containing liposomes as membrane models for different T cell subpopulations}, series = {Journal of Functional Biomaterials}, volume = {13}, journal = {Journal of Functional Biomaterials}, number = {3}, issn = {2079-4983}, doi = {10.3390/jfb13030111}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-286130}, year = {2022}, abstract = {A fine balance of regulatory (T\(_{reg}\)) and conventional CD4\(^+\) T cells (T\(_{conv}\)) is required to prevent harmful immune responses, while at the same time ensuring the development of protective immunity against pathogens. As for many cellular processes, sphingolipid metabolism also crucially modulates the T\(_{reg}\)/T\(_{conv}\) balance. However, our understanding of how sphingolipid metabolism is involved in T cell biology is still evolving and a better characterization of the tools at hand is required to advance the field. Therefore, we established a reductionist liposomal membrane model system to imitate the plasma membrane of mouse T\(_{reg}\) and T\(_{conv}\) with regards to their ceramide content. We found that the capacity of membranes to incorporate externally added azide-functionalized ceramide positively correlated with the ceramide content of the liposomes. Moreover, we studied the impact of the different liposomal preparations on primary mouse splenocytes in vitro. The addition of liposomes to resting, but not activated, splenocytes maintained viability with liposomes containing high amounts of C\(_{16}\)-ceramide being most efficient. Our data thus suggest that differences in ceramide post-incorporation into T\(_{reg}\) and T\(_{conv}\) reflect differences in the ceramide content of cellular membranes.}, language = {en} } @article{JarickBertscheStahletal.2018, author = {Jarick, Marcel and Bertsche, Ute and Stahl, Mark and Schultz, Daniel and Methling, Karen and Lalk, Michael and Stigloher, Christian and Steger, Mirco and Schlosser, Andreas and Ohlsen, Knut}, title = {The serine/threonine kinase Stk and the phosphatase Stp regulate cell wall synthesis in Staphylococcus aureus}, series = {Scientific Reports}, volume = {8}, journal = {Scientific Reports}, number = {13693}, doi = {10.1038/s41598-018-32109-7}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177333}, year = {2018}, abstract = {The cell wall synthesis pathway producing peptidoglycan is a highly coordinated and tightly regulated process. Although the major components of bacterial cell walls have been known for decades, the complex regulatory network controlling peptidoglycan synthesis and many details of the cell division machinery are not well understood. The eukaryotic-like serine/threonine kinase Stk and the cognate phosphatase Stp play an important role in cell wall biosynthesis and drug resistance in S. aureus. We show that stp deletion has a pronounced impact on cell wall synthesis. Deletion of stp leads to a thicker cell wall and decreases susceptibility to lysostaphin. Stationary phase Δstp cells accumulate peptidoglycan precursors and incorporate higher amounts of incomplete muropeptides with non-glycine, monoglycine and monoalanine interpeptide bridges into the cell wall. In line with this cell wall phenotype, we demonstrate that the lipid II:glycine glycyltransferase FemX can be phosphorylated by the Ser/Thr kinase Stk in vitro. Mass spectrometric analyses identify Thr32, Thr36 and Ser415 as phosphoacceptors. The cognate phosphatase Stp dephosphorylates these phosphorylation sites. Moreover, Stk interacts with FemA and FemB, but is unable to phosphorylate them. Our data indicate that Stk and Stp modulate cell wall synthesis and cell division at several levels.}, language = {en} } @article{LichterPaulPaulietal.2022, author = {Lichter, Katharina and Paul, Mila Marie and Pauli, Martin and Schoch, Susanne and Kollmannsberger, Philip and Stigloher, Christian and Heckmann, Manfred and Sir{\´e}n, Anna-Leena}, title = {Ultrastructural analysis of wild-type and RIM1α knockout active zones in a large cortical synapse}, series = {Cell Reports}, volume = {40}, journal = {Cell Reports}, number = {12}, doi = {10.1016/j.celrep.2022.111382}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300913}, year = {2022}, abstract = {Rab3A-interacting molecule (RIM) is crucial for fast Ca\(^{2+}\)-triggered synaptic vesicle (SV) release in presynaptic active zones (AZs). We investigated hippocampal giant mossy fiber bouton (MFB) AZ architecture in 3D using electron tomography of rapid cryo-immobilized acute brain slices in RIM1α\(^{-/-}\) and wild-type mice. In RIM1α\(^{-/-}\), AZs are larger with increased synaptic cleft widths and a 3-fold reduced number of tightly docked SVs (0-2 nm). The distance of tightly docked SVs to the AZ center is increased from 110 to 195 nm, and the width of their electron-dense material between outer SV membrane and AZ membrane is reduced. Furthermore, the SV pool in RIM1α\(^{-/-}\) is more heterogeneous. Thus, RIM1α, besides its role in tight SV docking, is crucial for synaptic architecture and vesicle pool organization in MFBs.}, language = {en} }