Shiga-like toxins — Verotoxin 1 (SLT-1) produced by certain E. coli strains is most similar in structure and action to which bacterial toxin?

Introduction / Context:Enterohemorrhagic E. coli (EHEC) produce Shiga-like (verotoxin) toxins that cause hemorrhagic colitis and can lead to hemolytic uremic syndrome. Understanding toxin homology clarifies pathogenesis and informs diagnostic tests and antitoxin strategies.

Given Data / Assumptions:

• Verotoxin 1 (SLT-1) is produced by EHEC such as E. coli O157:H7.
• Shigella dysenteriae type 1 produces classic Shiga toxin.
• Toxins can share receptor specificity and enzymatic mechanisms.

Concept / Approach:Verotoxin 1 is closely related to Shigella dysenteriae Shiga toxin, both binding the Gb3 receptor and inactivating the 60S ribosomal subunit via N-glycosidase activity, thereby halting protein synthesis. In contrast, cholera toxin and E. coli heat-labile toxin are ADP-ribosylating toxins that activate adenylate cyclase to raise cAMP; the heat-stable toxin increases cGMP via guanylate cyclase activation. Therefore, the best match for similarity is Shiga toxin.

Step-by-Step Solution:

Verification / Alternative check:Immunoassays and genetic probes often cross-detect Shiga and Shiga-like toxins due to homology, supporting the similarity.

Why Other Options Are Wrong:

• Cholera toxin / heat-labile E. coli toxin: stimulate cAMP, not ribosome inactivation.
• Heat-stable toxin: increases cGMP, distinct mechanism and structure.

Common Pitfalls:Confusing clinical syndromes: watery secretory diarrhea (cAMP/cGMP toxins) versus bloody diarrhea and HUS (Shiga-like toxins).

Final Answer:shiga toxin