title: CodY deletion enhances in vivo virulence of community-associated methicillin-resistant Staphylococcus aureus clone USA300.
abstract: The Staphylococcus aureus global regulator CodY responds to nutrient availability by controlling the expression of target genes. In vitro, CodY represses the transcription of virulence genes, but it is not known if CodY also represses virulence in vivo. The dominant community-associated methicillin-resistant S. aureus (CA-MRSA) clone, USA300, is hypervirulent and has increased transcription of global regulators and virulence genes; these features are reminiscent of a strain defective in CodY. Sequence analysis revealed, however, that the codY genes of USA300 and other sequenced S. aureus isolates are not significantly different from the codY genes in strains known to have active CodY. codY was expressed in USA300, as well as in other pulsotypes assessed. Deletion of codY from a USA300 clinical isolate resulted in modestly increased expression of the global regulators agr and saeRS, as well as the gene encoding the toxin alpha-hemolysin (hla). A substantial increase (>30-fold) in expression of the lukF-PV gene, encoding part of the Panton-Valentine leukocidin (PVL), was observed in the codY mutant. All of these expression differences were reversed by complementation with a functional codY gene. Moreover, purified CodY protein bound upstream of the lukSF-PV operon, indicating that CodY directly represses expression of lukSF-PV. Deletion of codY increased the virulence of USA300 in necrotizing pneumonia and skin infection. Interestingly, deletion of lukSF-PV from the codY mutant did not attenuate virulence, indicating that the hypervirulence of the codY mutant was not explained by overexpression of PVL. These results demonstrate that CodY is active in USA300 and that CodY-mediated repression restrains the virulence of USA300.
authors.affiliation: Section of Critical Care, University of Chicago, Chicago, Illinois, USA. cmontgomery@bsd.uchicago.edu
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Montgomery
authors.forename: Susan
authors.initials: S
authors.lastname: Boyle-Vavra
authors.forename: Agnès
authors.initials: A
authors.lastname: Roux
authors.forename: Kazumi
authors.initials: K
authors.lastname: Ebine
authors.forename: Abraham L
authors.initials: AL
authors.lastname: Sonenshein
authors.forename: Robert S
authors.initials: RS
authors.lastname: Daum
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D001427:Bacterial Toxins / Q000096:biosynthesis; D004269:DNA, Bacterial / Q000378:metabolism; D005098:Exotoxins / Q000096:biosynthesis; D017353:Gene Deletion; D005816:Genetic Complementation Test; D006460:Hemolysin Proteins / Q000096:biosynthesis; D007956:Leukocidins / Q000096:biosynthesis; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics / Q000472:pathogenicity*; D051379:Mice; D008810:Mice, Inbred C57BL; D011485:Protein Binding; D011494:Protein Kinases / Q000096:biosynthesis; D012097:Repressor Proteins / Q000172:deficiency* / Q000235:genetics; D013203:Staphylococcal Infections / Q000382:microbiology* / Q000473:pathology*; D015534:Trans-Activators / Q000096:biosynthesis; D014157:Transcription Factors; D014774:Virulence; D037521:Virulence Factors / Q000096:biosynthesis
chemical_list: C095698:Agr protein, Staphylococcus aureus; D001426:Bacterial Proteins; D001427:Bacterial Toxins; C540555:CodY protein, Staphylococcus aureus; D004269:DNA, Bacterial; D005098:Exotoxins; D006460:Hemolysin Proteins; D007956:Leukocidins; C078284:Panton-Valentine leukocidin; D012097:Repressor Proteins; C433805:SaeR protein, Staphylococcus aureus; D015534:Trans-Activators; D014157:Transcription Factors; D037521:Virulence Factors; C021091:staphylococcal alpha-toxin; D011494:Protein Kinases; C527351:SaeS protein, Staphylococcus aureus