AB5 toxin
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The AB5 (or AB5) toxins are six-component protein complexes secreted by a number of pathogenic bacteria. All share a similar structure and mechanism for entering targeted host cells.[1]
Structure and mechanism [edit]
A complete AB5 toxin complex contains six protein units. Five – the B subunits – are similar or identical in structure; the remaining A subunit is unique.
The A subunit (or a portion thereof) of an AB5 toxin is the portion of the complex responsible for toxicity. Typically it will have enzymatic activity inside the host cell.
The B subunits form a pentameric (five-membered) ring, into which one end of the A subunit extends and is held. This B subunit ring is also capable of binding to a receptor on the surface of the host cell.[2] (Without the B subunits, the A subunit has no way of attaching to or entering the cell, and thus no way to exert its toxic effect.)
List of AB5 toxins [edit]
- Campylobacter jejuni enterotoxin (from Campylobacter jejuni)
- cholera toxin (Vibrio cholerae)
- heat-labile enterotoxins (LT and LT-II) (Escherichia coli)
- pertussis toxin (Bordetella pertussis)
- shiga toxin (Shigella dysenteriae)
- shiga-like toxin (or verotoxin) (enterohemorrhagic varieties of E. coli including O157:H7)
References [edit]
- ^ Merritt E, Hol W (1995). "AB5 toxins". Curr Opin Struct Biol 5 (2): 165–71. doi:10.1016/0959-440X(95)80071-9. PMID 7648317.
- ^ Lencer W, Saslowsky D (2005). "Raft trafficking of AB5 subunit bacterial toxins". Biochim Biophys Acta 1746 (3): 314–21. doi:10.1016/j.bbamcr.2005.07.007. PMID 16153723.
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