Shiga toxin 1 subunit B (Stx1B)

Shiga toxin 1 subunit B (Stx1B) is the pentameric, receptor-binding component of the Shiga toxin produced by Shigella dysenteriae and enterohemorrhagic Escherichia coli (EHEC) (UniProt P09385). It functions as a lectin, specifically binding to the glycosphingolipid globotriaosylceramide (Gb3) on the plasma membrane of host cells, such as renal glomerular endothelial cells (PubMed: 11544340). This binding is a prerequisite for the internalization of the holotoxin via endocytosis and its subsequent retrograde trafficking to the endoplasmic reticulum (PubMed: 21903821). Once the toxin reaches the cytosol, the A subunit halts protein synthesis, leading to cell death and clinical manifestations like hemorrhagic colitis and hemolytic uremic syndrome (HUS) (NIH: StatPearls - Shiga Toxin). As the B subunit mediates the initial step of infection, it is a critical target for therapeutic interventions, including neutralizing monoclonal antibodies like Urtoxazumab and synthetic Gb3 analogs designed to sequester the toxin before it can bind to host tissues (PubMed: 16988246). Additionally, its high affinity for Gb3-expressing cells has led to research into its use as a targeted delivery vehicle for imaging agents or therapeutics in certain cancers (PubMed: 25663153).

Other names

Verotoxin 1 subunit BShiga-like toxin 1 subunit BSLT-1BStx1B

Neutralization of toxin binding to the globotriaosylceramide (Gb3) receptor on host cell surfaces, preventing toxin internalization and subsequent cytotoxicity.