Cholera toxin acts by which mechanism?
Overactivates adenylate cyclase (cAMP) by permanently activating Gs
Mimics the adenylate cyclase enzyme (cAMP)
Overactivates guanylate cyclase (cGMP)
Inactivate elongation factor (EF-2)
Ans. a. Overactivates adenylate cyclase (cAMP) by permanently activating GsCholera toxin binds and activates Gs, resulting in very high levels of intracellular cAMP. This rise in cAMP opens luminal Cl- channels, causing a massive secretory diarrhea.TOXINS WITH A-B ADP-RIBOSYL TRANSFERASE ACTIVITYToxin ADP-Ribosylated Host ProteinEffect on Host CellPseudomonas Exotoxin SExotoxin A UnknowneEF-2Inhibits translocation during protein synthesisDiphtheria toxin eEF-2Inhibits translocation during protein synthesisE. coliHeat-labile toxin (LT)Heat-stable toxin (ST)G-protein (GS)Increases cAMP in intestinal epithelium causing diarrheaIncreases cGMP in, which decreases the resorption of NaCI and H20 in gutCholera toxin G-protein (GS)Increases cAMP in intestinal epithelium causing diarrheaPertussis toxin G-protein (Gi)Increases cAMP causing edema, lymphocytosis and increased insulin secretionEdema toxin Mimics the adenylate cyclase enzyme (Increases cAMP)Shiga toxin (ST) Inactivate 60S ribosome by removing adenine from rRNA
Bacteria