Heat-stable enterotoxin B (STB) of Escherichia coli : structure, mechanism, and role in intestinal secretion, barrier dysfunctions and inflammation

Abstract

Enterotoxigenic Escherichia coli (ETEC) is a primary causative agent of diarrheal disease in humans and domesticated animals, leading to considerable worldwide disease burden, death, and financial consequences. Among ETEC’s virulence determinants, the heat-stable enterotoxin b (STb) is a less researched component, distinguished by a special mode of action, unlike the other ETEC enterotoxins. STb is a 48-amino acid peptide enterotoxin encoded by the estB plasmid gene. The pathogenesis of STb involves the binding of the enterotoxin to the sulfatide receptor, leading to the oligomerization and formation of pores, which induce a rise in calcium, disruption of tight junctions, and finally, the induction of diarrhea. There is still a need to understand the structure of the pores, the complete range of receptors, and the exact role in the pathogenesis of the disease, especially in humans. This review aims to summarize the current understanding of the heat-stable STb, including the structure, genetics, and pathophysiology, and the gaps in the current knowledge.