Which of the following toxins disrupts protein synthesis by targeting ribosomes?

Diphtheria toxin is uniquely known for its mechanism of disrupting protein synthesis within host cells by specifically targeting ribosomes. This toxin is produced by the bacterium Corynebacterium diphtheriae and functions by inactivating elongation factor-2 (EF-2), which is crucial for the protein synthesis process. When EF-2 is inactivated, the ribosome cannot properly translate mRNA into proteins, leading to cellular dysfunction and ultimately cell death.

The other toxins listed, while they have significant effects on human health, do not primarily inhibit protein synthesis through the same ribosomal targeting mechanism as diphtheria toxin. For instance, tetanus toxin is known for blocking neurotransmitter release, botulinum toxin causes paralysis by preventing acetylcholine release at neuromuscular junctions, and staphylococcal enterotoxin functions mainly as a superantigen, stimulating an excessive immune response rather than inhibiting protein synthesis directly. This distinction highlights the specific action mechanism by which diphtheria toxin elicits its harmful effects.