@article{KonteTerpitzPlemenitaš2016, author = {Konte, Tilen and Terpitz, Ulrich and Plemenitaš, Ana}, title = {Reconstruction of the High-Osmolarity Glycerol (HOG) Signaling Pathway from the Halophilic Fungus Wallemia ichthyophaga in Saccharomyces cerevisiae}, series = {Frontiers in Microbiology}, journal = {Frontiers in Microbiology}, doi = {10.3389/fmicb.2016.00901}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-165214}, year = {2016}, abstract = {The basidiomycetous fungus Wallemia ichthyophaga grows between 1.7 and 5.1 M NaCl and is the most halophilic eukaryote described to date. Like other fungi, W. ichthyophaga detects changes in environmental salinity mainly by the evolutionarily conserved high-osmolarity glycerol (HOG) signaling pathway. In Saccharomyces cerevisiae, the HOG pathway has been extensively studied in connection to osmotic regulation, with a valuable knock-out strain collection established. In the present study, we reconstructed the architecture of the HOG pathway of W. ichthyophaga in suitable S. cerevisiae knock-out strains, through heterologous expression of the W. ichthyophaga HOG pathway proteins. Compared to S. cerevisiae, where the Pbs2 (ScPbs2) kinase of the HOG pathway is activated via the SHO1 and SLN1 branches, the interactions between the W. ichthyophaga Pbs2 (WiPbs2) kinase and the W. ichthyophaga SHO1 branch orthologs are not conserved: as well as evidence of poor interactions between the WiSho1 Src-homology 3 (SH3) domain and the WiPbs2 proline-rich motif, the absence of a considerable part of the osmosensing apparatus in the genome of W. ichthyophaga suggests that the SHO1 branch components are not involved in HOG signaling in this halophilic fungus. In contrast, the conserved activation of WiPbs2 by the S. cerevisiae ScSsk2/ScSsk22 kinase and the sensitivity of W. ichthyophaga cells to fludioxonil, emphasize the significance of two-component (SLN1-like) signaling via Group III histidine kinase. Combined with protein modeling data, our study reveals conserved and non-conserved protein interactions in the HOG signaling pathway of W. ichthyophaga and therefore significantly improves the knowledge of hyperosmotic signal processing in this halophilic fungus.}, language = {en} } @article{EisenhardtSprengerRoeringetal.2016, author = {Eisenhardt, Anja E. and Sprenger, Adrian and R{\"o}ring, Michael and Herr, Ricarda and Weinberg, Florian and K{\"o}hler, Martin and Braun, Sandra and Orth, Joachim and Diedrich, Britta and Lanner, Ulrike and Tscherwinski, Natalja and Schuster, Simon and Dumaz, Nicolas and Schmidt, Enrico and Baumeister, Ralf and Schlosser, Andreas and Dengjel, J{\"o}rn and Brummer, Tilman}, title = {Phospho-proteomic analyses of B-Raf protein complexes reveal new regulatory principles}, series = {Oncotarget}, volume = {7}, journal = {Oncotarget}, number = {18}, doi = {10.18632/oncotarget.8427}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-166529}, pages = {26628-26652}, year = {2016}, abstract = {B-Raf represents a critical physiological regulator of the Ras/RAF/MEK/ERK-pathway and a pharmacological target of growing clinical relevance, in particular in oncology. To understand how B-Raf itself is regulated, we combined mass spectrometry with genetic approaches to map its interactome in MCF-10A cells as well as in B-Raf deficient murine embryonic fibroblasts (MEFs) and B-Raf/Raf-1 double deficient DT40 lymphoma cells complemented with wildtype or mutant B-Raf expression vectors. Using a multi-protease digestion approach, we identified a novel ubiquitination site and provide a detailed B-Raf phospho-map. Importantly, we identify two evolutionary conserved phosphorylation clusters around T401 and S419 in the B-Raf hinge region. SILAC labelling and genetic/biochemical follow-up revealed that these clusters are phosphorylated in the contexts of oncogenic Ras, sorafenib induced Raf dimerization and in the background of the V600E mutation. We further show that the vemurafenib sensitive phosphorylation of the T401 cluster occurs in trans within a Raf dimer. Substitution of the Ser/Thr-residues of this cluster by alanine residues enhances the transforming potential of B-Raf, indicating that these phosphorylation sites suppress its signaling output. Moreover, several B-Raf phosphorylation sites, including T401 and S419, are somatically mutated in tumors, further illustrating the importance of phosphorylation for the regulation of this kinase.}, language = {en} }