FIG 1.

CodY and Sae control virulence gene expression. (A) Schematic of the saePQRS locus. The green boxes at promoters denote SaeR binding sites. The weak but constitutive P3 promoter drives expression of saeRS; the P1 promoter is inducible and drives expression of saePQRS. (B) SaeS responds to multiple stimuli (yellow), and this promotes autophosphorylation of SaeS and phosphotransfer to SaeR. SaeR∼P can then bind its various targets. (C) Regulatory relationships between Agr, Rot, CodY, and Sae. Major global regulators under CodY control and known to affect sae P1 promoter activity are shown. The dashed lines indicate a potential indirect mechanism of CodY-mediated repression; the solid line indicates potential direct regulation. Question marks indicate an unknown or postulated regulatory mechanism.