Crystal structures of the Arabidopsis thaliana organellar RNA editing factors MORF1 and MORF9

In flowering plant plastids and mitochondria, multiple organellar RNA editing factor (MORF/RIP) proteins are required at most sites for efficient C to U RNA editing catalyzed by the RNA editosome. MORF proteins harbor a conserved stretch of residues (MORF-box), form homo- and heteromers and interact with selected PPR (pentatricopeptide repeat) proteins, which recognize each editing site. The molecular function of the MORF-box remains elusive since it shares no sequence similarity with known domains. We determined structures of the A. thaliana mitochondrial MORF1 and chloroplast MORF9 MORF-boxes which both adopt a novel globular fold (MORF domain). Our structures state a paradigmatic model for MORF domains and their specific dimerization via a hydrophobic interface. We cross-validate the interface by yeast two-hybrid studies and pulldown assays employing structure-based mutants. We find a structural similarity of the MORF domain to an N-terminal ferredoxin-like domain (NFLD), which confers RNA substrate positioning in bacterial 4-thio-uracil tRNA synthetases, implying direct RNA contacts of MORF proteins during RNA editing. With the MORF1 and MORF9 structures we elucidate a yet unknown fold, corroborate MORF interaction studies, validate the mechanism of MORF multimerization by structure-based mutants and pave the way towards a complete structural characterization of the plant RNA editosome

Polyglycerol coated polypropylene surfaces for protein and bacteria resistance

Polyglycerol (PG) coated polypropylene (PP) films were synthesized in a two- step approach that involved plasma bromination and subsequently grafting hyperbranched polyglycerols with very few amino functionalities. The influence of different molecular weights and density of reactive linkers were investigated for the grafted PGs. Longer bromination times and higher amounts of linkers on the surface afforded long-term stability. The protein adsorption and bacteria attachment of the PP-PG films were studied. Their extremely low amine content proved to be beneficial for preventing bacteria attachment

DYW domain structures imply an unusual regulation principle in plant organellar RNA editing catalysis

RNA上の遺伝情報を書き換える酵素であるDYWドメインの構造を解明 --植物オルガネラRNA編集のユニークな活性制御--. 京都大学プレスリリース. 2021-06-23.RNA editosomes selectively deaminate cytidines to uridines in plant organellar transcripts—mostly to restore protein functionality and consequently facilitate mitochondrial and chloroplast function. The RNA editosomal pentatricopeptide repeat proteins serve target RNA recognition, whereas the intensively studied DYW domain elicits catalysis. Here we present structures and functional data of a DYW domain in an inactive ground state and activated. DYW domains harbour a cytidine deaminase fold and a C-terminal DYW motif, with catalytic and structural zinc atoms, respectively. A conserved gating domain within the deaminase fold regulates the active site sterically and mechanistically in a process that we termed gated zinc shutter. Based on the structures, an autoinhibited ground state and its activation are cross-validated by RNA editing assays and differential scanning fluorimetry. We anticipate that, in vivo, the framework of an active plant RNA editosome triggers the release of DYW autoinhibition to ensure a controlled and coordinated cytidine deamination playing a key role in mitochondrial and chloroplast homeostasis

Evaluating the potential current brain-computer interfaces

Im Rahmen der Weiterentwicklung der Interaktion zwischen Menschen und Computern werden immer neue sogenannte Brain-Computer-Interfaces (BCI) entwickelt die es ermöglichen sollen, mittels Elektroenzephalografie (EEG), Steuersignale direkt vom Gehirn zu einem Computer zu übertragen. Diese Arbeit vergleicht zwei für den Endverbraucher bestimmten Brain-Computer-Interfaces und testet ihre Eignung in einem praxisnahen Anwendungsszenario

Research from the child's perspectice? Methodological and methodical reflections

Mit dem Anspruch, Forschung »aus der Perspektive von Kindern« zu betreiben, verbindet sich eine der zentralen Herausforderungen der neueren sozialwissenschaftlichen Kindheitsforschung und ihrer erziehungswissenschaftlichen Rezeption. Die differenten Verständnisse dessen, was es jeweils bedeutet, die Perspektive des Kindes einzunehmen, sind inzwischen vielfach methodologisch und forschungsethisch reflektiert worden. Zugleich hat sich ein differenziertes Feld der Forschung entwickelt, in dem unterschiedliche methodologische Zugänge und methodische Herangehensweisen erprobt worden sind, um die Sichtweisen der Kinder empirisch zur Geltung zu bringen. Der Workshop arbeitet zunächst den Stand der Forschung und der methodologischen Diskussion auf. Er bezieht dabei sowohl quantitative wie qualitative Studien mit ein. In einem zweiten Schritt bietet er die Gelegenheit, am Beispiel konkreter Forschungsvorhaben der Organisatorinnen, Organisatoren und Teilnehmer/-innen die Frage zu erörtern, wie sich die Perspektive des Kindes methodologisch konzeptualisieren und methodisch erschließen lässt. Eine besondere Aufmerksamkeit wird dabei auch der speziellen Herausforderung gewidmet, die »Perspektive des Kindes« im Falle von Altersgruppen zu ergründen, denen die Möglichkeiten zur sprachlichen Artikulation noch weitgehend fehlen

DNAJC19, a Mitochondrial Cochaperone Associated with Cardiomyopathy, Forms a Complex with Prohibitins to Regulate Cardiolipin Remodeling

SummaryProhibitins form large protein and lipid scaffolds in the inner membrane of mitochondria that are required for mitochondrial morphogenesis, neuronal survival, and normal lifespan. Here, we have defined the interactome of PHB2 in mitochondria and identified DNAJC19, mutated in dilated cardiomyopathy with ataxia, as binding partner of PHB complexes. We observed impaired cell growth, defective cristae morphogenesis, and similar transcriptional responses in the absence of either DNAJC19 or PHB2. The loss of PHB/DNAJC19 complexes affects cardiolipin acylation and leads to the accumulation of cardiolipin species with altered acyl chains. Similar defects occur in cells lacking the transacylase tafazzin, which is mutated in Barth syndrome. Our experiments suggest that PHB/DNAJC19 membrane domains regulate cardiolipin remodeling by tafazzin and explain similar clinical symptoms in two inherited cardiomyopathies by an impaired cardiolipin metabolism in mitochondrial membranes

DYW domain structures imply an unusual regulation principle in plant organellar RNA editing catalysis

RNA editosomes selectively deaminate cytidines to uridines in plant organellar transcripts—mostly to restore protein functionality and consequently facilitate mitochondrial and chloroplast function. The RNA editosomal pentatricopeptide repeat proteins serve target RNA recognition, whereas the intensively studied DYW domain elicits catalysis. Here we present structures and functional data of a DYW domain in an inactive ground state and activated. DYW domains harbour a cytidine deaminase fold and a C-terminal DYW motif, with catalytic and structural zinc atoms, respectively. A conserved gating domain within the deaminase fold regulates the active site sterically and mechanistically in a process that we termed gated zinc shutter. Based on the structures, an autoinhibited ground state and its activation are cross-validated by RNA editing assays and differential scanning fluorimetry. We anticipate that, in vivo, the framework of an active plant RNA editosome triggers the release of DYW autoinhibition to ensure a controlled and coordinated cytidine deamination playing a key role in mitochondrial and chloroplast homeostasis

Determination of the Antioxidant Status of the Skin by In Vivo-Electron Paramagnetic Resonance (EPR) Spectroscopy

Organisms produce free radicals which are essential for various metabolic processes (enzymatic oxidation, cellular respiration, signaling). Antioxidants are important chemical compounds that specifically prevent the oxidation of substances by scavenging radicals, especially reactive oxygen species (ROS). Made up of one or two unpaired electrons, ROS are free radicals that are highly reactive and can attack other metabolites. By using electron paramagnetic resonance (EPR) spectroscopy, it is possible to measure paramagnetic substances such as free radicals. Therefore the dermal antioxidant activity can be determined by applying semi-stable radicals onto the skin and measuring the antioxidant-induced radical scavenging activity in the skin. In recent years, EPR has been developed as a spectroscopic method for determining the antioxidant status in vivo. Several studies have shown that an additional uptake of dietary supplements, such as carotenoids or vitamin C in physiological concentrations, provide a protective effect against free radicals. Using the EPR technique it could be demonstrated that the radical production in stress situations, such as irradiation with infrared and visible light, was reduced with time. However, not only the oral uptake of antioxidants, but also the topical application of antioxidants, e.g., a hyperforin-rich cream, is very useful against the development of oxidative stress. Regular application of a hyperforin-rich cream reduced radical formation. The skin lipids, which are very important for the barrier function of the skin, were also stabilized