FIG. 4.

(A) PrgY reduces the activity of cCF10 processed from both the iCF10 and the cAM373 signal peptides. Supernatant from JRC107 or JRC110 (Eep⁻) strains harboring pPCR4 or pJRC3 and pMSP3545Y (expressing PrgY) or pMS3545 (vector) were used to induce exponentially growing OG1RF(p043lacZ) strains, and the ability of supernatant cCF10 to induce LacZ expression of this strain was measured by β-galactosidase assay and expressed in Miller units. The PrgY-dependent percent reduction of cCF10 activity (+PrgY/Vector) was averaged from three independent experiments (error bars represent the standard deviation of three independent experiments). (B) PrgY does not decrease endogenous cAM373 activity. Cell culture supernatants prepared as for Table 3 were diluted twofold, and the pheromone activity is represented as the inverse of the largest dilution able to aggregate an OG1RF(pCF10) or OG1RF(pAM373::pAD2) indicator strain. The titers represent the results of two independent experiments; the same results were seen for both assays.