Characterization of the genetic switch from phage ɸ13 important for Staphylococcus aureus colonization in humans

Bacteriophage ɸ13 belongs to a group of phages that carries virulence factors and colonizes human strains ofStaphylococcus aureus. Knowledge about the mechanism behind the genetic switch that decides between lysogeny (prophage integration) or lysis (bacterial killing) is important for combatingS.  aureus infection. Using the switch region from ɸ13, we have created reporter plasmids that mimic the decision phase and can detect prophage-inducing conditions. AbstractTemperate phages are bacterial viruses that after infection either reside integrated into a bacterial genome as prophages forming lysogens or multiply in a lytic lifecycle. The decision between lifestyles is determined by a switch involving a phage-encoded repressor, CI, and a promoter region from which lytic and lysogenic genes are divergently transcribed. Here, we investigate the switch of phage ɸ13 from the human pathogenStaphylococcus aureus. ɸ13 encodes several virulence factors and is prevalent inS.  aureus strains colonizing humans. We show that the ɸ13 switch harbors acI gene, a predictedmor (modulator of repression) gene, and three high-affinity operator sites binding CI. To quantify the decision between lytic and lysogenic lifestyle, we introduced reporter plasmids that carry the 1.3  kb switch region from ɸ13 with the lytic promoter fused tolacZ intoS.  aureus andBacillus subtilis. Analysis of β-galactosidase expression indicated that decision frequency is independent of host factors. The white...
Source: MicrobiologyOpen - Category: Microbiology Authors: Tags: ORIGINAL ARTICLE Source Type: research