Serotype F double‐ and triple‐converting phage insertionally inactivate the Staphylococcus aureus β‐toxin determinant by a common molecular mechanism

The precise molecular mechanism of Staphylococcus aureus β‐toxin inactivation by the serotype F triple‐converting phage φ42, φA1 and φA3 was investigated. Sequence analysis of the φ42 (attP) and Staphylococcus aureus (attB) attachment sites and the left (attL) and right (attR) chromosomal/bacteriophage DNA junctions of individual lysogens, each harbouring a triple‐converting phage, revealed the presence of a common 14‐bp core sequence in all four sites. These findings indicate that the genomes of the triple‐converting phage integrate into the 5′‐end of the β‐toxin gene (hlb) by a site‐ and orientation‐specific mechanism identical to that previously described for the serotype F double‐converting phage φ13.