Interestingly, Ubeda et al. have reported that other factors as antibiotic treatment can mediate SOS response in staphylococci and promote horizontal dissemination of pathogenicity
island-encoded virulence factor genes [44]. The postulated mechanism of SOS-induced induction and transfer of ICESt1/3 elements involves autoproteolysis of cI type repressor Arp1 [23, 45]. As the RD2 element Combretastatin A4 ic50 encodes multiple cI type repressors [1] it is plausible that the mechanism of RD2 induction is mediated by SOS-induced proteolysis or autoproteolysis of one of the RD2 cI regulators. The induction of RD2 was not observed after treatment with hydrogen peroxide i.e. in the condition of oxidative stress that is known to induce phages JNJ-26481585 purchase [46–48]. That suggests rather LexA selleck products dependent mechanism induced by DNA damage. In conclusion, RD2 is a medium host range mobile element that is shared between multiple unrelated
serotypes of GAS and other pathogenic streptococcal species. As a consequence of several extracellular secreted proteins encoded by RD2, the element may confer a selective advantage on organisms that acquire this element by horizontal gene transfer. Acknowledgements We thank S. Beres and P. Sumby for advice and K. Stockbauer for critical reading of the manuscript. Electronic supplementary material Additional file 1: Table S1: Streptococcal strains used in the study (DOC 67 KB) Additional file 2: Table S2: Primers used for the mutant construction (DOC 29 KB) Additional file 3: Supplemental Methods (DOC 28 KB) Additional file 4: Figure S1: Conformation of proper mutant construction (DOC 441 KB) Additional file 5: Figure
S2: Determination of MIC values for mitomycin C and hydrogen ADP ribosylation factor peroxide (PNG 312 KB) Additional file 6: Table S3: Homologs of RD2 genes found in GBS (XLS 36 KB) Additional file 7: Figure S3: Induction of prophages and ICE elements in MGAS6180 after treatment with mitomycin C and hydrogen peroxide. (PNG 92 KB) References 1. Green NM, Zhang S, Porcella SF, Nagiec MJ, Barbian KD, Beres SB, LeFebvre RB, Musser JM: Genome sequence of a serotype M28 strain of group A Streptococcus : potential new insights into puerperal sepsis and bacterial disease specificity. J Infect Dis 2005,192(5):760–770.PubMedCrossRef 2. Green NM, Beres SB, Graviss EA, Allison JE, McGeer AJ, Vuopio-Varkila J, LeFebvre RB, Musser JM: Genetic diversity among type emm 28 group A Streptococcus strains causing invasive infections and pharyngitis. J Clin Microbiol 2005,43(8):4083–4091.PubMedCrossRef 3. Beres SB, Musser JM: Contribution of exogenous genetic elements to the group A Streptococcus metagenome. PLoS One 2007,2(8):e800.PubMedCrossRef 4. Lancefield RC: Differentiation of group A streptococci with a common R antigen into three serological types, with special reference to the bactericidal test. J Exp Med 1957,106(4):525–544.PubMedCrossRef 5.