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Updated: Aug 23, 2026

Using the Overlay Assay to Qualitatively Measure Bacterial Production of and Sensitivity to Pneumococcal Bacteriocins
Published on: September 30, 2014
The streptococcolytic enzyme zoocin A is a penicillin-binding protein
Lucie S Heath1, Harry E Heath, Paul A LeBlanc
1Department of Biological Sciences, The University of Alabama, Box 870334, Tuscaloosa, AL 35487-0334, USA.
Abstract:
Zoocin A is a streptococcolytic enzyme produced by Streptococcus equi subsp. zooepidemicus 4881 that has an unknown site of action on the peptidoglycans of susceptible organisms. Analysis of a mutant strain in which the genes for zoocin A and resistance to zoocin A were inactivated revealed that this strain was more susceptible to beta-lactam antibiotics than the parental organism. Purified zoocin A had weak beta-lactamase activity, bound radioactive penicillin covalently, and its streptococcolytic activity was inhibited by penicillin. Thus, zoocin A is a penicillin-binding protein and presumably is a D-alanyl endopeptidase.
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