FIG 5.

The conserved 37-nt sequence from P1_csfB is sufficient to reduce σ^G-dependent activation of a promoter ordinarily recognized by σ^F and σ^G. (A) Cartoon of P1_csfB, P_fin, and a chimeric promoter (P_csfB-fin) in which the 37-nt conserved sequence from P1_csfB was substituted for the corresponding 37 nt in P_fin. Also shown is the ^mut1P_csfB-fin promoter construct in which the 7-nt sequence mutated in ^mut1P1_csfB is introduced into P_csfB-fin (marked by mut1). The −35 and −10 elements for each promoter are indicated as shaded boxes; note that P_csfB and P_fin have identical −35 elements. (B) The P_csfB-fin promoter but not ^mut1P_csfB-fin displays significantly reduced activation by σ^G. β-Galactosidase production from P_fin (triangles), P_csfB-fin (closed circles), and ^mut1P_csfB-fin (open circles) fusions to lacZ (inserted at the amyE locus) was measured during sporulation of otherwise wild-type strains (strains KF76, KF129, KF130, and KF166, respectively). (C) Q Tyr-28 is required for maximal levels of σ^G activation of P_fin. P_fin-lacZ reporter gene expression was monitored in strains harboring Q⁺ or Q^Y28A (strains KF146 and KF152, respectively). (D) σ^G-dependent activation of P_csfB-fin is unmasked in the Q^Y28A mutant. P_csfB-fin-lacZ reporter gene expression was monitored in strains harboring Q⁺ or Q^Y28A (strains KF147 and KF153, respectively). In all strains for which the results are shown in panels C and D, the native Q gene was deleted and either Q⁺ or Q^Y28A was encoded at the sacA locus. Reporters were inserted at amyE.