title: Transcription of the phage-encoded Panton-Valentine leukocidin of Staphylococcus aureus is dependent on the phage life-cycle and on the host background.
abstract: Panton-Valentine leukocidin (PVL) is a pore-forming, bi-component toxin secreted by Staphylococcus aureus strains epidemiologically associated with diseases such as necrotizing pneumonia and skin and soft-tissue infections. Here we demonstrate that transcription of the phage-encoded PVL (encoded in the luk-PV operon) is dependent on two major determinants: the phage life-cycle and the host chromosomal background. Mitomycin C induction of PVL-encoding prophages from different community-acquired MRSA strains led to an increase in the amount of luk-PV mRNA as a result of read-through transcription from latent phage promoters and an increase in phage copy numbers. Failing prophage excision was reflected in a constant expression of luk-PV as in the case of strain USA300, suggesting that phi Sa2USA300 is a replication-defective prophage. Additionally, we could show that luk-PV transcription is influenced by the S. aureus global virulence regulators agr and sae. We found a strong impact of the host background on prophage induction and replication when analysing PVL phages in different S. aureus strains. For example phage phi Sa2mw was greatly induced by mitomycin C in its native host MW2 and in strain Newman but to a considerably lesser extent in strains 8325-4, RN6390 and ISP479c. This discrepancy was not linked to the SOS response of the bacteria since recA transcription did not vary between the strains. These results suggest a fine tuning between certain phages and their host, with major impact on the expression of phage-encoded virulence genes.
authors: Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Tübingen, Elfriede-Aulhorn-Str. 6, 72076 Tübingen, Germany.
authors: Christiane
authors: C
authors: Wirtz
authors: Robert-Koch-Institut Wernigerode, Burgstr. 37, 38855 Wernigerode, Germany.
authors: Wolfgang
authors: W
authors: Witte
authors: Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Tübingen, Elfriede-Aulhorn-Str. 6, 72076 Tübingen, Germany.
authors: Christiane
authors: C
authors: Wolz
authors: Institut für Medizinische Mikrobiologie und Hygiene, Universitätsklinikum Tübingen, Elfriede-Aulhorn-Str. 6, 72076 Tübingen, Germany.
authors: Christiane
authors: C
authors: Goerke
mesh_terms: D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D004279:DNA, Viral / Q000235:genetics; D005098:Exotoxins / Q000235:genetics / Q000378:metabolism*; D007956:Leukocidins / Q000235:genetics / Q000378:metabolism*; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity / Q000821:virology; D016685:Mitomycin / Q000494:pharmacology; D011938:Rec A Recombinases / Q000378:metabolism; D013203:Staphylococcal Infections / Q000382:microbiology*; D013204:Staphylococcus Phages / Q000502:physiology*; D014158:Transcription, Genetic; D014774:Virulence; D014775:Virus Activation
chemical_list: D001427:Bacterial Toxins; D004279:DNA, Viral; D005098:Exotoxins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin; D016685:Mitomycin; D011938:Rec A Recombinases