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Infection and Immunity, January 2009, p. 419-428, Vol. 77, No. 1
0019-9567/09/$08.00+0     doi:10.1128/IAI.00859-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

SarZ Promotes the Expression of Virulence Factors and Represses Biofilm Formation by Modulating SarA and agr in Staphylococcus aureus{triangledown}

Sandeep Tamber and Ambrose L. Cheung*

Department of Microbiology and Immunology, Dartmouth Medical School, Hanover, New Hampshire 03755

Received 11 July 2008/ Returned for modification 20 August 2008/ Accepted 22 October 2008

Staphylococcus aureus is a remarkably adaptable organism capable of multiple modes of growth in the human host, as a part of the normal flora, as a pathogen, or as a biofilm. Many of the regulatory pathways governing these modes of growth are centered on the activities of two regulatory molecules, the DNA binding protein SarA and the regulatory RNAIII effector molecule of the agr system. Here, we describe the modulation of these regulators and their downstream target genes by SarZ, a member of the SarA/MarR family of transcriptional regulators. Transcriptional and phenotypic analyses of a sarZ mutant demonstrated that the decreased transcription of mgrA and the agr RNAIII molecule was accompanied by increased transcription of spa (protein A) and downregulation of hla (alpha-hemolysin) and sspA (V8 protease) transcripts when compared to its isogenic parent. The decrease in protease activity was also associated with an increase in SarA expression. Consistent with an increase in SarA levels, the sarZ mutant displayed an enhanced ability to form biofilms. Together, our results indicate that SarZ may be an important regulator governing the dissemination phase of S. aureus infections, as it promotes toxin expression while repressing factors required for biofilm formation.

* Corresponding author. Mailing address: Department of Microbiology and Immunology, Dartmouth Medical School, Hanover, NH 03755. Phone: (603) 650-1314. Fax: (603) 650-1318. E-mail: ambrose.cheung{at}dartmouth.edu

{triangledown} Published ahead of print on 27 October 2008.

Editor: A. Camilli

Infection and Immunity, January 2009, p. 419-428, Vol. 77, No. 1
0019-9567/09/$08.00+0     doi:10.1128/IAI.00859-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Poor, C. B., Chen, P. R., Duguid, E., Rice, P. A., He, C. (2009). Crystal Structures of the Reduced, Sulfenic Acid, and Mixed Disulfide Forms of SarZ, a Redox Active Global Regulator in Staphylococcus aureus. J. Biol. Chem. 284: 23517-23524 [Abstract] [Full Text]  
  • Ballal, A., Manna, A. C. (2009). Expression of the sarA family of genes in different strains of Staphylococcus aureus. Microbiology 155: 2342-2352 [Abstract] [Full Text]  


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