| Popis: |
Bacteriophages are crucial in shaping population of pathogens, such as Staphylococcus aureus. Prophages play an important role in the virulence, pathogenesis or host preference, as well as in horizontal gene transfer. On the other hand, broad host range staphylococcal bacteriophages of the genus Kayvirus are promising agents for therapeutic applications. The lysogens become immune to infection by closely related phages, but the interactions between temperate and lytic staphylococcal phages are not understood. We describe a resistance mechanism towards lytic phages of the genus Kayvirus, mediated by S. aureus prophage accessory gene. The responsible membrane-anchored protein shows the presence of a putative membrane-binding α-helix in its N-terminal part and a cytoplasmic positively charged C-terminus. We demonstrated that the mechanism of action does not prevent the infecting Kayvirus to adsorb onto the host cell, deliver its genome into the cell but, phage replication is halted. Changes in the cell membrane polarity and permeability, which lead to prophage-activated cell death were observed from 10 min after the infection. Furthermore, we describe a mechanism of overcoming resistance in a spontaneous host-range Kayvirus mutant in which a gene fusion has emerged, and which was selected on S. aureus strain harbouring a prophage encoding the immunity protein. |
