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BMC Microbiology

, 12:114

First Online: 21 June 2012Received: 31 October 2011Accepted: 23 May 2012DOI: 10.1186-1471-2180-12-114

Cite this article as: McDowell, E.J., Callegari, E.A., Malke, H. et al. BMC Microbiol 2012 12: 114. doi:10.1186-1471-2180-12-114


BackgroundThe production of Streptococcus pyogenes exoproteins, many of which contribute to virulence, is regulated in response to nutrient availability. CodY is a transcriptional regulator that controls gene expression in response to amino acid availability. The purpose of this study was to identify differences in the expression of streptococcal exoproteins associated with deletion of the codY gene.

ResultsWe compared the secreted proteins produced by wild-type S. pyogenes to a codY mutant in the post-exponential phase of growth. We used both one and two-dimensional gel electrophoresis to separate exoproteins. Proteins that were significantly different in abundance upon repeated analysis were identified with tandem mass spectrometry. The production of the secreted cysteine protease SpeB, a secreted chromosomally encoded nuclease SdaB, and a putative adhesion factor Spy49 0549 were more abundant in supernatant fluids obtained from the codY mutant. In addition, hyaluronidase HylA, CAMP factor Cfa, a prophage encoded nuclease Spd-3, and an uncharacterized extracellular protein Spy49 0015 were less abundant in supernatant fluids obtained from the codY mutant strain. Enzymatic assays showed greater DNase activity in culture supernatants isolated in the post-exponential phase of growth from the codY mutant strain compared to the wild-type strain. Because extracellular nucleases and proteases can influence biofilm formation, we also measured the ability of the strains to form biofilms during growth with both rich medium Todd Hewitt yeast extract; THY and chemically defined media CDM. No difference was observed with rich media but with CDM the biofilms formed by the codY mutant strain had less biomass compared to the wild-type strain.

ConclusionsOverall, the results indicate that CodY alters the abundance of a select group of S. pyogenes exoproteins, including DNases, a protease, and hylauronidase, which together may alleviate starvation by promoting dissemination of the pathogen to nutrient rich environments and by hydrolysis of host macromolecules.

Electronic supplementary materialThe online version of this article doi:10.1186-1471-2180-12-114 contains supplementary material, which is available to authorized users.

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Autor: Emily J McDowell - Eduardo A Callegari - Horst Malke - Michael S Chaussee


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