In summary, we have provided genetic evidence to suggest that two structurally distinct transcriptional regulators of virulence from two different Gram-positive pathogens contain a novel conserved Aro-Cys-(Aro/Xle)-Aro motif that enables them to translate the signal of carbohydrate availability to appropriately regulate the expression of virulence genes required for host infection. The gene discussed is CYP19A1; the disease is infection.