High-confidence glycosome proteome for procyclic form <em>Trypanosoma brucei</em> by epitope-tag organelle enrichment and SILAC proteomics

The glycosome of the pathogenic African trypanosome Trypanosoma brucei is a specialized peroxisome that contains most of the enzymes of glycolysis and several other metabolic and catabolic pathways. The contents and transporters of this membrane-bounded organelle are of considerable interest as potential drug targets. Here we use epitope tagging, magnetic bead enrichment, and SILAC quantitative proteomics to determine a high-confidence glycosome proteome for the procyclic life cycle stage of the parasite using isotope ratios to discriminate glycosomal from mitochondrial and other contaminating proteins. The data confirm the presence of several previously demonstrated and suggested pathways in the organelle and identify previously unanticipated activities, such as protein phosphatases. The implications of the findings are discussed

Polyglutamine tracts as modulators of transcriptional activation from yeast to mammals

Abstract Microsatellite repeats are genetically unstable and subject to expansion and shrinkage. A subset of them, triplet repeats, can occur within the coding region and specify homomeric tracts of amino acids. Polyglutamine (polyQ) tracts are enriched in eukaryotic regulatory proteins, notably transcription factors, and we had shown before that they can contribute to transcriptional activation in mammalian cells. Here we generalize this finding by also including evolutionarily divergent organisms, namely, Drosophila and baker's yeast. In all three systems, Gal4-based model transcription factors were more active if they harbored a polyQ tract, and the activity depended on the length of the tract. By contrast, a polyserine tract was inactive. PolyQs acted from either an internal or a C-terminal position, thus ruling out a merely structural "linker" effect. Finally, a two-hybrid assay in mammalian cells showed that polyQ tracts can interact with each other, supporting the concept that a polyQ-containing transcription factor can recruit other factors with polyQ tracts or glutamine-rich activation domains. The widespread occurrence of polyglutamine repeats in regulatory proteins suggests a beneficial role; in addition to the contribution to transcriptional activity, their genetic instability might help a species to adapt to changing environmental conditions in a potentially reversible manner

Oxidation behaviour of particle reinforced MoSi2 composites at temperatures up to 1700°C

The topic Oxidation behaviour of particle reinforced MoSi2 composites at temperatures up to 1700°C is discussed in a three part publication. In the first part of this paper a literature survey on the oxidation behaviour of MoSi2 and MoSi2 composites has been given. In the second part an initial screening at 1600°C revealed those composites which may be suitable for high temperature applications. The low temperature oxidation behaviour of selected composites in the pest region was examined as well. Additionally, the effect of iron impurities on the high temperature behaviour of the composites was explained. The present part deals with a detailed investigation of an optimised MoSi2/HfO2 composite. These investigations include high temperature oxidation at 1500 to 1700°C and low temperature oxidation at 400 and 500°C.The financial support of these investigations by the Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie (BMBF) (contract number 03 N 2015 C1) is gratefully acknowledged by the authors