The toxin's structure is composed of two subunits: an A subunit with enzymatic activity and five B subunits responsible for binding to specific receptors on the surface of host cells. The B subunits play a critical role in targeting the toxin to cells by binding to glycosphingolipid receptors, particularly globotriaosylceramide (Gb3), which are abundant on the surfaces of human intestinal and renal cells. Once the B subunits have successfully docked the toxin to the cell, the A subunit is translocated into the cytoplasm, where it exerts its toxic effects. The A subunit cleaves a specific adenine residue from the 28S rRNA of the ribosome, an essential component of the cellular machinery responsible for protein synthesis. This cleavage halts protein synthesis, leading to cellular dysfunction and ultimately, cell death.
Infections caused by Shiga toxin-producing E. coli (STEC) are particularly dangerous due to the toxin’s ability to cause severe gastrointestinal illness. Patients typically experience symptoms such as abdominal cramps, diarrhea (which is often bloody), and vomiting. The severity of the illness can escalate when the toxin enters the bloodstream, potentially leading to hemolytic uremic syndrome (HUS). HUS is a serious condition characterized by the destruction of red blood cells, which can lead to acute kidney failure, especially in young children and the elderly.
Preventing Shiga toxin infections is crucial, as there is no specific treatment for STEC infections. Preventive measures include proper food handling and hygiene practices, such as thoroughly cooking meat, avoiding unpasteurized dairy products, and washing hands and produce thoroughly. In the event of an infection, management focuses on supportive care, particularly maintaining hydration and electrolyte balance, to help the body cope with the effects of the toxin. In severe cases, hospitalization may be required to manage complications and prevent long-term damage to vital organs.
Shiga Toxin: Mechanism, Impact, and Prevention of a Potent Bacterial Toxin
