A-B exotoxins
Definition
A-B exotoxins are bacterial proteins consisting of two components: an 'A' (active) part that exerts toxic effects, and a 'B' (binding) part that facilitates entry into host cells. These toxins disrupt cellular processes, often leading to disease symptoms.
5 Must Know Facts For Your Next Test
- A-B exotoxins are composed of two subunits: A (enzyme activity) and B (cell binding).
- The B subunit binds to host cell receptors, allowing the A subunit to enter the cell.
- Common examples include diphtheria toxin, cholera toxin, and botulinum toxin.
- These toxins can interfere with protein synthesis or signal transduction pathways in host cells.
- They are typically produced by Gram-positive bacteria but can also be found in some Gram-negative bacteria.
Review Questions
- What are the roles of the A and B subunits in A-B exotoxins?
- Name three diseases caused by bacteria producing A-B exotoxins.
- How do A-B exotoxins typically enter host cells?
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Related terms
Endotoxin: Toxic components of the outer membrane of certain Gram-negative bacteria released upon cell death.
Virulence Factor: Molecules produced by pathogens that contribute to their ability to cause disease.
Toxin-antitoxin system: A set of two or more closely linked genes encoding both a toxin and its corresponding antitoxin.
