Characterization of the genetic switch from phage ɸ13 important for Staphylococcus aureus colonization in humans. Issue 5 (14th October 2021)

• Record Type: Journal Article
• Authors: Kristensen, Camilla S.; Varming, Anders K.; Leinweber, Helena A. K.; Hammer, Karin; Lo Leggio, Leila; Ingmer, Hanne; Kilstrup, Mogens
• Is Part Of: MicrobiologyOpen. Volume 10:Issue 5(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-10-14
• Subjects: bacteriophage -- genetic switch -- lysogeny -- ɸ13 -- phi13 -- prophage -- repressor -- Staphylococcus aureus; Microbiology -- Periodicals; 579
• DOI: 10.1002/mbo3.1245
• Languages: English
• ISSNs: 2045-8827

Abstract

Abstract: Temperate 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 pathogen Staphylococcus aureus . ɸ13 encodes several virulence factors and is prevalent in S. aureus strains colonizing humans. We show that the ɸ13 switch harbors a cI gene, a predicted mor (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 to lacZ into S. aureus and Bacillus subtilis . Analysis of β‐galactosidase expression indicated that decision frequency is independent of host factors. The white "lysogenic" phenotype, which relies on the expression of cI, could be switched to a stable blue "lytic" phenotype by DNA damaging agents. We have characterized lifestyle decisions of phage ɸ13, and our approach may be applied to other temperate phages encoding virulence factors in S. aureus . Abstract : Bacteriophage ɸ13 belongs to a group of phages that carries virulence factors and colonizes human strains of Staphylococcus aureus . Knowledge about the mechanism behind the genetic switch that decides between lysogeny (prophage integration) or lysis (bacterial killing) is important for combating S. aureus infection. Using the switch region from ɸ13, we have created reporter plasmids that mimic the decision phase and can detect prophage‐inducing conditions.