Omanische Heilpflanze im Fokus der Phytochemie IPB-Wissenschaftler und Partner aus Dhofar haben jüngst die omanische Heilpflanze Terminalia dhofarica unter die phytochemische Lupe genommen. Die Pflanze ist reich an…
Geschmack ist vorhersagbar: Mit FlavorMiner. FlavorMiner heißt das Tool, das IPB-Chemiker und Partner aus Kolumbien jüngst entwickelt haben. Das Programm kann, basierend auf maschinellem Lernen (KI), anhand der…
Bäumler, J.; Riber, W.; Klecker, M.; Müller, L.; Dissmeyer, N.; Weig, A. R.; Mustroph, A.;AtERF#111/ABR1 is a transcriptional activator involved in the wounding responsePlant J.100969-990(2019)DOI: 10.1111/tpj.14490
AtERF#111/ABR1 belongs to the group X of the ERF/AP2 transcription factor family (GXERFs) and is shoot specifically induced under submergence and hypoxia. It was described to be an ABA‐response repressor, but our data reveal a completely different function. Surprisingly, AtERF#111 expression is strongly responsive to wounding stress. Expression profiling of ERF#111‐overexpressing (OE) plants, which show morphological phenotypes like increased root hair length and number, strengthens the hypothesis of AtERF#111 being involved in the wounding response, thereby acting as a transcriptional activator of gene expression. Consistent with a potential function outside of oxygen signalling, we could not assign AtERF#111 as a target of the PRT6 N‐degron pathway, even though it starts with a highly conserved N‐terminal Met−Cys (MC) motif. However, the protein is unstable as it is degraded in an ubiquitin‐dependent manner. Finally, direct target genes of AtERF#111 were identified by microarray analyses and subsequently confirmed by protoplast transactivation assays. The special roles of diverse members of the plant‐specific GXERFs in coordinating stress signalling and wound repair mechanisms have been recently hypothesized, and our data suggest that AtERF#111 is indeed involved in these processes.
Publikation
Chen, Y.; Hoehenwarter, W.;Rapid and reproducible phosphopeptide enrichment by tandem metal oxide affinity chromatography: application to boron deficiency induced phosphoproteomicsPlant J.98370-384(2019)DOI: 10.1111/tpj.14215
Mass spectrometry has been instrumental in enabling the study of molecular signaling on a cellular scale by way of site‐specific quantification of protein post‐translational modifications, in particular phosphorylation. Here we describe an updated tandem metal oxide affinity chromatography (MOAC) combined phosphoprotein/phosphopeptide enrichment strategy, a scalable phosphoproteomics approach that allows rapid identification of thousands of phosphopeptides in plant materials. We implemented modifications to several steps of the original tandem MOAC procedure to increase the amount of quantified phosphopeptides and hence site‐specific phosphorylation of proteins in a sample beginning with the less amounts of tissue and a substantially smaller amount of extracted protein. We applied this technology to generate time‐resolved maps of boron signaling in Arabidopsis roots. We show that the successive enrichment of phosphoproteins in a first and phosphopeptide extraction in a second step using our optimized procedure strongly enriched the root phosphoproteome. Our results reveal that boron deficiency affects over 20% of the measured root phosphoproteome and that many phosphorylation sites with known biological function, and an even larger number of previously undescribed sites, are modified during the time course of boron deficiency. We identify transcription factors as key regulators of hormone signaling pathways that modulate gene expression in boron deprived plants. Furthermore, our phosphorylation kinetics data demonstrate that mitogen‐activated protein kinase (MAPK) cascades mediate polarized transport of boron in Arabidopsis roots. Taken together, we establish and validate a robust approach for proteome‐wide phosphorylation analysis in plant biology research.
Publikation
Eisenschmidt-Bönn, D.; Schneegans, N.; Backenköhler, A.; Wittstock, U.; Brandt, W.;Structural diversification during glucosinolate breakdown: mechanisms of thiocyanate, epithionitrile and simple nitrile formationPlant J.99329-343(2019)DOI: 10.1111/tpj.14327
Secondary metabolism is characterized by an impressive structural diversity. Here, we have addressed the mechanisms underlying structural diversification upon damage‐induced activation of glucosinolates, a group of thioglucosides found in the Brassicales. The classical pathway of glucosinolate activation involves myrosinase‐catalyzed hydrolysis and rearrangement of the aglucone to an isothiocyanate. Plants of the Brassicaceae possess specifier proteins, i.e. non‐heme iron proteins that promote the formation of alternative products by interfering with this reaction through unknown mechanisms. We have used structural information available for the thiocyanate‐forming protein from Thlaspi arvense (TaTFP), to test the impact of loops protruding at one side of its β‐propeller structure on product formation using the allylglucosinolate aglucone as substrate. In silico loop structure sampling and semiempirical quantum mechanical calculations identified a 3L2 loop conformation that enabled the Fe2+ cofactor to interact with the double bond of the allyl side chain. Only this arrangement enabled the formation of allylthiocyanate, a specific product of TaTFP. Simulation of 3,4‐epithiobutane nitrile formation, the second known product of TaTFP, required an alternative substrate docking arrangement in which Fe2+ interacts with the aglucone thiolate. In agreement with these results, substitution of 3L2 amino acid residues involved in the conformational change as well as exchange of critical amino acid residues of neighboring loops affected the allylthiocyanate versus epithionitrile proportion obtained upon myrosinase‐catalyzed allylglucosinolate hydrolysis in the presence of TaTFP in vitro. Based on these insights, we propose that specifier proteins are catalysts that might be classified as Fe2+‐dependent lyases.