Gudula Schmidt

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Endotoxins of Gram-negative microbes fulfill as components of the outer membrane a vital function for bacterial viability and, if set free, induce in mammalians potent pathophysiological effects. Chemically, they are lipopolysaccharides (LPS) consisting of an O-specific chain, a core oligosaccharide, and a lipid component, termed lipid A. The latter(More)
The actin cytoskeleton is regulated by GTP-hydrolysing proteins, the Rho GTPases, which act as molecular switches in diverse signal-transduction processes. Various bacterial toxins can inactivate Rho GTPases by ADP-ribosylation or glucosylation. Previous research has identified Rho proteins as putative targets for Escherichia coli cytotoxic necrotizing(More)
Clostridium botulinum exoenzyme C3 inactivates the small GTPase Rho by ADP-ribosylation. We used a C3 fusion toxin (C2IN-C3) with high cell accessibility to study the kinetics of Rho inactivation by ADP-ribosylation. In primary cultures of rat astroglial cells and Chinese hamster ovary cells, C2IN-C3 induced the complete ADP-ribosylation of RhoA and(More)
The bacterium Photorhabdus luminescens is mutualistically associated with entomopathogenetic nematodes. These nematodes invade insect larvae and release the bacteria from their intestine, which kills the insects through the action of toxin complexes. We elucidated the mode of action of two of these insecticidal toxins from P. luminescens. We identified the(More)
The YopE cytotoxin of Yersinia pseudotuberculosis is an essential virulence determinant that is injected into the eukaryotic target cell via a plasmid-encoded type III secretion system. Injection of YopE into eukaryotic cells induces depolymerization of actin stress fibres. Here, we show that YopE exhibits a GTPase-activating protein (GAP) activity and that(More)
The cytotoxic necrotizing factor 1 (CNF1) from Escherichia coli has been shown to activate members of the Rho family by deamidation of glutamine 63. This amino acid is essential for hydrolysis of GTP, and any substitution results in a constitutively active Rho. Activation of Rho induces the formation of stress fibers, filopodia, and membrane ruffles due to(More)
Pseudomonas aeruginosa exoenzyme S (ExoS) is a bifunctional cytotoxin. The ADP-ribosyltransferase domain is located within the C terminus part of ExoS. Recent studies showed that the N terminus part of ExoS (amino acid residues 1-234, ExoS(1-234)), which does not possess ADP-ribosyltransferase activity, stimulates cell rounding when transfected or(More)
The autoimmune blistering skin diseases pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are mainly caused by autoantibodies against desmosomal cadherins. In this study, we provide evidence that PV-immunoglobulin G (IgG) and PF-IgG induce skin blistering by interference with Rho A signaling. In vitro, pemphigus IgG caused typical hallmarks of pemphigus(More)
The cytotoxic necrotizing factor 1 (CNF1) activates Rho GTPases by deamidation of glutamine-63 and thereby induces redistribution of the actin cytoskeleton and formation of stress fibers. Here, we have studied the effects of CNF1 on the transepithelial resistance of Caco-2 cells, a human intestinal epithelial cell line, in comparison with the(More)
Directional cell migration is crucially dependent on the spatiotemporal control of intracellular signalling events. These events regulate polarized actin dynamics, resulting in protrusion at the front of the cell and contraction at the rear. The actin cytoskeleton is regulated through signalling by Rho-like GTPases, such as RhoA, which stimulates(More)