Identification and Characterization of a New Prespore-Specific Regulatory Gene, rsfA, of Bacillus subtilis

Differential gene expression during Bacillus subtilis sporulation is controlled by sigma factors and other regulatory effectors. The first compartmentalized sigma factor, ς(F), is active specifically in the prespore compartment. During our screening for new chromosome segregation mutants using a ς(F)-dependent gpr-lacZ reporter as a probe, we identified a new gene (ywfN) required for maximal expression of the reporter and named it rsfA. The product of rsfA has features of gene regulatory proteins, and the protein colocalizes with DNA. The expression of rsfA is under the control of both ς(F) and ς(G). Null mutations in rsfA have different effects on the expression of ς(F)-dependent genes, suggesting that the RsfA protein is a regulator of transcription that fine-tunes gene expression in the prespore.