Effect of CovR polymorphisms on GAS gene expression. Streptococcus pyogenes

In this study we sought to determine the effects of single amino acid replacements in the control of virulence regulatory (CovR) regulatory protein on group A streptococcal global gene expression. Overall design: We compared the transcriptomes of the serotype M3 strain MGAS10870 with four derivative strains: 1) a strain in which CovR had been completely inactivated (CovR knockout); 2) a strain in which the Arg 144 amino acid was changed to a cysteine (CovR-R144C); 3) a strain in which the Arg 158 amino acid was changed to a cysteine (CovR-R158C); and 4) a strain in which the the Asn 193 amino acid was changed to an isoleucine (CovR-N193I). Duplicate samples of each strain were grown to mid-exponential phase and the relative transcriptomes were compared using an Affymetrix GeneChipl.