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Medical Microbiology (Fach) / Production of Toxins (Lektion)
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- Naming Bacterial Species (cholera toxin) Enzymatic activity (ADP-ribosylysetoxin) capital letters (toxin A)
- Exotoxins AB-toxins cytolytic superantigens heat stable peptides
- AB-toxin A subunit (Enzyme) B subunit (binds to host cell)
- ADP ribosyltransferase Cholera toxin Uses NAD as ADP ribose donor ribose binds to and destroys: GTP binding proteins and elongation factor 2 Water is removed from the cell (Diarrhea) Funktion is deactivation of macrophages
- N-glycosidases Shiga toxin (shigella dysenteriae) or shiga like toxin (EHEC) hydrolysis of N-glycosidic bond in 28S RNA protein translation stops epithelial cells die water resorption reduced = diarrhea
- Metallo endoproteases tetanus toxin (chlostridium tetani) botulinum toxin(C.botulinum) both neurotoxins
- Botulinum toxin binds to presynaptic membranes cleaves proteins needed for vesicles to fuse with membrane inhibition of acetylcholine release WASP WAIST
- Tetanus Toxin Clostridium tetani inhibits glycin release permanent release of acetylcholine permanent innervation twitching paralysis SEAL POSITION
- Adenylcyclase produces cAMP exflux of water targets immune cells Cholera
- B-subunit used as vaccine harmless on their own
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- Cytolytic toxins pore formation cleave component of cytoplasmic membrane
- Cytolytic: Lysteriolysin Streptolysin alpha toxin target cholesterol pore formation
- Cytolytic Toxins: Phospholipidase cleaves heads (phospholipids) from tails C.perfringens
- Cytolytic Toxins:Sphingomyelinase S. aureus beta toxin cleaves Sphingomyeline into ceramid and phosphorylcholin Sphingomyelin part of cell membrane (destroyed)
- Superantigens normal recognition 1:10000 Superantigen makes T-cells bind to any receptor may result in toxic shock
- Heat stable toxin peptides <2000 Da Citrobacter freudii Yersinia enterocolitica activate GTP -> cGMP water loss diarrhea
- AB-toxins: diphteria toxin A subunit blocks elongation factor 2 no more protein synthesis
- Endotoxins: Gram negative bacteria lipopolysacharades lipid A is toxic releases after lysis of bacteria
- Endotoxins: Gram Positive bacteria teichoic acid macrophage ingestion kills bacteria interleukin I in hypothalamus causes fever
- Limulus assay CRAB Endotoxin turn blood solid
- Advantages of toxins Ingestion benefit unknown Toxin on body surface protects from anti bodies toxin in deeper tissue produces anoxic environment (necrotic tissue)