When branched chain find more amino acids are depleted, DNA affinity decreases allowing the initiation of transcription. Although usually considered to be a repressor, CodY activates expression of acetate kinase [21] and bsfF, which is a small RNA in B. subtilis[22]. In S. pyogenes, CodY controls the expression of genes involved in the response to nutritional stress, including genes encoding exoproteins. The

transcript levels of 34 genes were previously compared between a wild-type strain of S. pyogenes and a codY mutant derivative by using quantitative reverse transcriptase PCR (qRT-PCR) [18]. Eleven of the genes were predicted to encode secreted proteins. The expression of four of these genes (grab sagA sdaB/mf-1, and speB) was greater in the wild-type strain compared to the mutant strain, while the expression of the remaining seven was less (nga prtS scl scpA ska slo speH). Subsequently, by using DNA microarrays, inactivation of codY in S. pyogenes was found to alter the transcription of approximately 17% of genes in the chromosome, click here including several that encoded exoproteins [23]. Together, the results indicate that CodY is a global regulator controlling the transcription of a variety of

genes, including some encoding exoproteins, which are likely to influence host-pathogen interactions [18, 23]. The purpose of this study was to compare the exoproteins of a wild-type strain of S. pyogenes to a codY mutant strain to identify potential differences derived either at the transcriptional or post-transcriptional level. The results confirmed, at the protein level, several differences in expression previously predicted by transcript analyses and identified additional exoproteins with altered abundance following the deletion of

codY. Results Analysis of exoproteins by SDS-PAGE As an initial step to identify differences in exoprotein production between a codY mutant and a wild-type strain of S. pyogenes, the strains were grown to the stationary phase of growth and culture supernatant proteins (CSPs) were analysed by using SDS-PAGE gel electrophoresis. There was no difference in either the growth rate or growth yield of the two strains (Figure 1). mafosfamide Separation of CSPs by using SDS-PAGE showed several differences in the amounts of specific proteins (Figure 2). Seven protein bands were excised from the gel and analysed with tandem mass spectrometry (MS/MS; Additional file 1: Table S1, Additional file 2, Table S2). The results indicated that hyalurondidase (HylA; Spy49_0811c), which degrades hyaluronic acid present in the extracellular matrix of host tissue and the bacterial capsule, a 5’-nucleotidase (Spy49_0686c), a secreted protein with similarity to amidases (Spy49_0015), and a hypothetical protein possessing a type II secretion signal (Spy49_0816) were more abundant in the supernatant fluid obtained from the wild-type strain (Figure 2).