ChIP-seq of the response regulator CovR in Group B Streptococcus (GBS)

We report the characterization of the major regulator of virulence gene expression (CovR) in Group B Streptococcus. The ChIP-seq experiments define the binding of CovR on the chromosome of the BM110 strain, a representative of the hypervirulent GBS lineage responsible of neonatal meningitis. Regulatory evolution of CovR signaling was investigated by comparing ChIP-seq done in parallel in a second GBS clinical isolate (NEM316) not belonging to the hypervirulent lineage. Overall design: In order to define the CovR binding regions along the genome of the GBS, we expressed an ectopic flagged variant of CovR (CovR-3XFLAG) under the control of a anhydrotetracycline (aTc) inducible promoter in a ?covR background. This functional FLAG-CovR variant was used for ChIP-sequencing with immunoprecipitations done on exponentially growing bacteria in THY + Hepes 50 mM. Two independent replicates were done for each sample (Rep1 and Rep2). CovR-FLAG were induced with 50 and 200 ng/ml aTc in the cultures. The controls are the non-induced condition (no-aTc) and the non-epitope tagged CovR strain (no-TAG). Experiments were done in the BM110 and NEM316 strains.