Eine Betrachtung über Kettenspannungsänderung durch Fachaushebung

Bei der Erzeugung eines aus chemischen Fasern bestandenen Gewebes erscheint es besonderes von grösster Wichtigkeit, zunächst den Einfluss der Fachaushebung auf die Kettfäden schärfer zu präzisieren und die Gewebequalität und ihre Einstellung vervollzukommen. Nämlich sollen sich alle Kettfäden während des Webens in einem Zustand gleichmässiger Spannung befinden, damit ein reines Webfach entsteht, in das der Schussfaden eingetragen und an den Warenrand angeschlagen warden kann. Im allgemeinen kann dies durch das Zusammenwirken von Kettenablass- und Warenabziehvorrichtungen eingestell t werden. Aus statischem Gesichtpunkt haben wir zunächst versuchsweise die Kettenspannungsänderung durch Fachaushebung untersucht. Hierbei haben wir zum Zweck gehabt, die geeignetesten Fachbildegetriebe fiir das Weben mit chemischen Fasern entwerfen zu können

A reversible phospho-switch mediated by ULK1 regulates the activity of autophagy protease ATG4B

Upon induction of autophagy, the ubiquitin-like protein LC3 is conjugated to phosphatidylethanolamine (PE) on the inner and outer membrane of autophagosomes to allow cargo selection and autophagosome formation. LC3 undergoes two processing steps, the proteolytic cleavage of pro-LC3 and the de-lipidation of LC3-PE from autophagosomes, both executed by the same cysteine protease ATG4. How ATG4 activity is regulated to co-ordinate these events is currently unknown. Here we find that ULK1, a protein kinase activated at the autophagosome formation site, phosphorylates human ATG4B on serine 316. Phosphorylation at this residue results in inhibition of its catalytic activity in vitro and in vivo. On the other hand, phosphatase PP2A-PP2R3B can remove this inhibitory phosphorylation. We propose that the opposing activities of ULK1-mediated phosphorylation and PP2A-mediated dephosphorylation provide a phospho-switch that regulates the cellular activity of ATG4B to control LC3 processing

Elucidation of the anti-autophagy mechanism of the Legionella effector RavZ using semisynthetic LC3 proteins

Autophagy is a conserved cellular process involved in the elimination of proteins and organelles. It is also used to combat infection with pathogenic microbes. The intracellular pathogen Legionella pneumophila manipulates autophagy by delivering the effector protein RavZ to deconjugate Atg8/LC3 proteins coupled to phosphatidylethanolamine (PE) on autophagosomal membranes. To understand how RavZ recognizes and deconjugates LC3-PE, we prepared semisynthetic LC3 proteins and elucidated the structures of the RavZ:LC3 interaction. Semisynthetic LC3 proteins allowed the analysis of structure-function relationships. RavZ extracts LC3-PE from the membrane before deconjugation. RavZ initially recognizes the LC3 molecule on membranes via its N-terminal LC3-interacting region (LIR) motif. The RavZ α3 helix is involved in extraction of the PE moiety and docking of the acyl chains into the lipid-binding site of RavZ that is related in structure to that of the phospholipid transfer protein Sec14. Thus, Legionella has evolved a novel mechanism to specifically evade host autophagy