Fig. 3. Exogenous iCF10 rescues the ability of PrgX mutants to repress prgQ transcription in p043lacZ. Beta-galactosidase activity was measured in extracts from OG1RF cells carrying p043lacZ derivatives containing mutations in prgX conferring single amino acid substitutions.

A. Fully derepressed (Class A) or partially depressed, uninducible (Class B) PrgX mutants in p043lacZ were grown in medium with or without 250 ng ml⁻¹ iCF10. Controls: WT = p043lacZ; WT + c = WT + 5 ng ml⁻¹ cCF10, dX = p043lacZdX.

B. Partially derepressed, inducible (Class C) mutations of PrgX were grown in medium with various combinations of iCF10 and cCF10. None = no peptide addition; cCF10 = 5 ng ml⁻¹ cCF10; iCF10 only = 250 ng ml⁻¹ iCF10; cCF10 + iCF10 = 5 ng ml⁻¹ cCF10 + 250 ng ml⁻¹ iCF10.