FIG. 1.

(A) The ptsI-splAB region of B. subtilis (open bars) and the endpoints of deletion derivatives cloned in plasmid ptrpBG-1 (shaded bars). Positions and directions of primers 1, 2, and 3 (numbered circles) used in RT-PCR are denoted by arrowheads. Numbers refer to the coordinates of deletion endpoints, restriction sites, transcription start sites, and the endpoints of RT-PCR products in the cloned splAB operon sequence (8). A translational fusion to lacZ (hatched bar) was created at the BclI site at coordinate 1373 of the splB gene (24). (B) Levels of β-galactosidase activity expressed from the amyE locus by the deletion derivatives outlined in panel A in spores of strains either lacking (strain WN356) or carrying (strain WN355) the splA gene at its natural locus. Values of β-galactosidase activity were normalized to those of strain WN459 carrying the wild-type Δ2 splB-lacZ at amyE and a complete deletion of the natural splAB operon. Specific β-galactosidase activity of strain WN459 was 151.1 ± 17.7 U. β-Galactosidase activity expressed by the Δ4 splB-lacZ fusion (asterisks) was not detectable (Fajardo-Cavazos and Nicholson, Unpublished observation). The data are expressed as averages and standard deviations for two independent duplicate determinations.