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Characterization of the genetic switch from phage phi13 important for Staphylococcus aureus colonization in humans
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  • Camilla Kristensen,
  • Anders Varming,
  • Helena Leinweber,
  • Karin Hammer,
  • Leila Lo Leggio,
  • Hanne Ingmer,
  • Mogens Kilstrup
Camilla Kristensen
Technical University of Denmark

Corresponding Author:camilla_s_k@hotmail.com

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Anders Varming
University of Copenhagen
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Helena Leinweber
University of Copenhagen Faculty of Life sciences
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Karin Hammer
Technical University of Denmark
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Leila Lo Leggio
University of Copenhagen
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Hanne Ingmer
University of Copenhagen Faculty of Life sciences
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Mogens Kilstrup
Technical University of Denmark
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Abstract

Temperate phages are bacterial viruses that either reside integrated in a bacterial genome as lysogens or enter a lytic lifecycle. 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 phi13 from the human pathogen Staphylococcus aureus. phi13 encodes several virulence factors and is prevalent in S. aureus strains colonizing humans. We show that the phi13 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 phi13 with the lytic promoter fused to lacZ into S. aureus and B. subtilis. Analysis of beta-galactosidase expression indicated that decision frequency is independent of host factors. The white “lysogenic” phenotype, which relies on expression of cI, could be switched to a stable blue “lytic” phenotype by DNA damaging agents. We have characterized lifestyle decisions of phage phi13, and our approach may be applied to other temperate phages encoding virulence factors in S. aureus.
29 Jul 2021Submitted to MicrobiologyOpen
30 Jul 2021Submission Checks Completed
30 Jul 2021Assigned to Editor
30 Jul 2021Reviewer(s) Assigned
23 Aug 2021Review(s) Completed, Editorial Evaluation Pending
24 Aug 2021Editorial Decision: Revise Major
19 Sep 20211st Revision Received
20 Sep 2021Submission Checks Completed
20 Sep 2021Assigned to Editor
20 Sep 2021Review(s) Completed, Editorial Evaluation Pending
20 Sep 2021Reviewer(s) Assigned
30 Sep 2021Editorial Decision: Accept