Heat-stable enterotoxin

Heat-stable enterotoxin B, secretory
Symbol STb_secrete
Pfam InterPro PROSITE PDOC00246
Heat-stable enterotoxin ST
structural characteristics for biological activity of heat-stable enterotoxin produced by enterotoxigenic escherichia coli: x-ray crystallography of weakly toxic and nontoxic analogs
Symbol Enterotoxin_ST
Pfam InterPro PROSITE PDOC00246
Heat stable E.coli enterotoxin 1
Symbol Enterotoxin_HS1
Pfam InterPro IPR012557

Heat-stable enterotoxins (STs) are secretory peptides produced by some bacterial strains, such as enterotoxigenic Escherichia coli[2] which are in general toxic to animals.

These peptides keep their 3D structure and remain active at temperatures as high as 100 °C.


Different STs recognize distinct receptors on the surface of animal cells and thereby affect different intracellular signaling pathways. For example, STa enterotoxins bind and activate membrane-bound guanylate cyclase, which leads to the intracellular accumulation of cyclic GMP and downstream effects on several signaling pathways.[3][4][5][6] These events lead to the loss of electrolytes and water from intestinal cells.

Heat-stable toxin 1 of entero-aggregative Escherichia coli (EAST1) is a small toxin. It is not, however, solely associated with entero-aggregative E. coli but also with many other diarrhoeic E. coli families. Some studies have established the role of EAST1 in some human outbreaks of diarrhoea. Isolates from farm animals have been shown to carry the astA gene coding for EAST1. However, the relation between the presence of EAST1 and disease is not conclusive.[7]


The mature STa protein from Escherichia coli, which is the cause of acute diarrhoea in infants and travellers in developing countries, is a 19-residue peptide containing three disulphide bridges that are functionally important. STa contains an N-terminal signal peptide composed of two domains, Pre and Pro, involved in extracellular toxin release, and a core enterotoxigenic domain.[8]

Members of heat-stable enterotoxin B family assume a helical secondary structure, with two alpha helices forming a disulfide cross-linked alpha-helical hairpin. The disulfide bonds are crucial for the toxic activity of the protein, and are required for maintenance of the tertiary structure, and subsequent interaction with the particulate form of guanylate cyclase, increasing cyclic GMP levels within the host intestinal epithelial cells.[9]


This article incorporates text from the IPR001489

This article incorporates text from the IPR015160

This article incorporates text from the IPR012557

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