Enterotoxigenic Escherichia coli heat-stable toxin (ST)

Enterotoxigenic Escherichia coli (ETEC) heat-stable toxin (ST) is a small, cysteine-rich peptide secreted by ETEC strains, which are a leading cause of secretory diarrhea in humans and livestock [1][2]. The toxin primarily exists in two forms, STa and STb, with STa being the most clinically significant in human disease [3]. STa functions by mimicking the endogenous intestinal peptides guanylin and uroguanylin to bind and activate the transmembrane receptor guanylate cyclase C (GC-C) on the apical surface of enterocytes [2][4]. This activation triggers an increase in intracellular cyclic GMP (cGMP), which subsequently activates the cystic fibrosis transmembrane conductance regulator (CFTR) and inhibits sodium-hydrogen exchangers, leading to a massive efflux of electrolytes and water into the intestinal lumen [4]. While the toxin itself is a primary virulence factor and a target for vaccine development, its structural framework has been leveraged therapeutically; synthetic analogs of STa, such as linaclotide and plecanatide, are used to treat chronic idiopathic constipation and irritable bowel syndrome with constipation by promoting intestinal secretion and motility [5][6]. Research into neutralizing ST through vaccines or monoclonal antibodies remains a critical area for preventing ETEC-related morbidity and mortality in developing regions [1][7].

Other names

STaSTbHeat-stable enterotoxinETEC STSThSTpEnterotoxin ST

Drugs targeting this molecule or its pathway either neutralize the toxin to prevent receptor binding or, in the case of therapeutic analogs, mimic the toxin's structure to bind and activate the Guanylate cyclase C (GC-C) receptor, thereby increasing intracellular cGMP and promoting intestinal fluid secretion.