Shigatoksiner

Shigatoksiner is a potent neurotoxin produced by the bacterium Shigella dysenteriae type 1, which is a leading cause of bacterial dysentery and bacillary dysentery. The toxin is responsible for the severe gastrointestinal symptoms associated with these infections, including abdominal pain, diarrhea, and sometimes bloody stools. Shigatoksiner acts by inhibiting the release of acetylcholine from motor neurons at the neuromuscular junction, leading to paralysis of the intestinal muscles and subsequent dysentery.

The toxin is composed of two subunits: A and B. The B subunit binds to gangliosides on the surface of cells, facilitating the entry of the A subunit into the cell. The A subunit then inhibits the enzyme GDP-fucose: GDP-mannose 3,4-alpha-mannosyltransferase II, which is essential for the synthesis of complex glycans on the cell surface. This inhibition disrupts the normal function of the cell, leading to the symptoms of dysentery.

Shigatoksiner is highly specific for the bacterium Shigella dysenteriae type 1 and is not produced by other strains of Shigella or by other bacterial species. The toxin is also highly potent, with a lethal dose of approximately 100 ng/kg in mice. Due to its potency and specificity, shigatoksiner is a valuable tool for studying the mechanisms of bacterial pathogenesis and for the development of vaccines and therapeutics against Shigella dysenteriae type 1.