Wild type versus PerR mutant Streptococcus pyogenes

In Streptococcus pyogenes, mutation of the peroxide sensor PerR results in avirulence despite producing hyper-resistance to peroxide stress. To understand the basis of this effect, global transcription profiling was conducted. Keywords: Study of the regulation of gene expression by PerR A S. pyogenes genespecific microarray, consisting of 60 to 80-mer oligonucleotides representing 517 genes out of a total of 1752 predicted open reading frames in the SF370 genome, was constructed. S. pyogenes wild type strain (HSC5) or HdeltaPerR strain (PerR mutant derived form the wild type strain HSC5) were grown in Todd-Hewitt broth supplemented with 0.2% yeast extract (THY medium) to mid-logarithmic phase of growth (OD600=0.3). RNA was extracted, amplified, and hybridized to the arrays. Each experiment consisted of a pair-wise competitive hybridization of amplified RNA samples from the wild type and PerR mutant derived RNA. Since 2 biological replicates were tested in duplicate with a reciprocal dye-flip, a total of eight DNA microarrays were used for comparison for each set of RNA amplifications.