However, RD2 copy number increased by 1 h, 2 h, 3 h, and 16 h-post mitomycin C treatment (Figure 5D). Of note, we also detected increases in the copy number of genes encoded by several other integrative elements present in the genome of strain MGAS6180. For example, all three tested prophages were induced. In the most dramatic case of prophage 6180.2 (encoding SpeK, a superantigen, and SlaA, a secreted phospholipase A2 virulence factor) we observed a increase in relative copy number over 700 times compared with the pre-induction level (Additional File 7, Figure S3). Consistent with phage induction, mitomycin C treatment resulted in a rapid decrease

in optical density of the culture, presumably corresponding to cell lysis (Figure 5A). Treatment with hydrogen peroxide did not increase RD2 copy number (Figure 5C), however Rapamycin nmr we observed induction of phages such as 6180.1 and 6180.2 (Additional File 7 Figure S3). An RD2-like element is present in group C and G Streptococcus strains Inasmuch as genome sequence information (Figure 1) and filter-mating data

presented herein suggested that RD2 or an RD2-like element can spread between streptococcal species and multiple serotypes, we tested the hypothesis that the RD2 element has a phylogenetic distribution broader than GAS and GBS. To test the hypothesis, we screened 20 group C (GCS) and G (GGS) streptococci causing human infections by PCR for the presence of seven RD2 genes encoding putative extracellular secreted proteins. The primers and conditions CHIR-99021 cell line we used were selleck chemicals llc based on the sequence of RD2 found in GAS strain MGAS6180, and have been used previously to study the distribution of RD2 in GAS strains [1]. Because specific primers were used, this PCR analysis tests for the presence of genes with high homology to the RD2 element in GAS. The majority of the 20 GCS and GGS strains tested have homologs of RD2 element genes (Table 2A). DNA sequencing of all PCR products confirmed that the amplified gene

fragments were homologues of RD2 element genes (data not shown). To test the hypothesis that the amplified genes were organized in an RD2-like genetic element, we used PCR primers described previously to tile across the entire RD2 element found in GAS strains [1]. The results (Table 2B) show that two GGS strains had an intact RD2 element, and one GCS strain had large segments of an intact RD2. The analysis also revealed a similar organization to RD2 in MGAS6180, as selleck chemicals amplicons of the same size were generated (data not shown). Missing products of tiling PCR of GCS encompass homologs of M28_Spy1325 and M28_Spy1326 (fragments 9-10) which genes detected in single PCR reactions (Table 2A). The failure to amplify PCR products corresponding to the junction sites between the chromosome and RD2 suggests that the element is located in a different chromosomal location than in GAS.