FIG 3 .
RovS and SHP1520 comprise a functional QS system in GBS. Regulation of Pshp1520 is mediated by both RovS and SHP1520. (A) Schematic diagram of DNA fragments used in transcriptional fusions with luxAB for use in GBS strains. Both reporters contain the putative shp1520 promoter, but pSar110 omits the rovS gene, whereas pSar111 includes rovS in its entirety. (B) Expression of Pshp1520 (pSar110) is autoinduced in cells containing both RovS and SHP1520 (A909). In strains lacking rovS (BLC100), shp1520 (BLC101), or both genes (BLC102), Pshp1520 is not induced. Additional copies of rovS on a plasmid (pSar111) complement the ΔrovS strain (BLC100) and slightly increase induction levels in the WT strain (A909). (C) Exogenous synthetic full-length SHP1520 peptide, as well as C8 peptide but not reverse peptides, induces Pshp1520 expression in BLC101(pSar110), thus complementing the shp1520 mutation. (D) sSHP2-C8 but not the reverse peptide induces Pshp1520 expression in a RovS-dependent manner. Data are shown as a function of relative light units (CPS/OD600) versus OD600. Each graph is representative of at least 3 biological replicates.