Acts as a transcriptional regulator. Probably redox-responsive. The apo- but not holo-form probably binds DNA (By similarity). Plays a positive role in prespore maturation and the initiation of sporulation septation. Anaerobically binds 1 [4Fe-4S] cluster per subunit; cluster is lost on exposure to O(2). Cluster is stabilized in the presence of mycothiol. Following nitrosylation of the [4Fe-4S] cluster binds 1 [4Fe-8(NO)] cluster per subunit. Optimum pH is 7.0 to 8.0 for 4Fe-4S stability. The 4Fe-4S form is a monomer; upon oxidation forms a disulfide-bonded homodimer. Expressed in exponential phase (PubMed:10708372). Expressed from 2 promoters at the onset of sporulation, no longer expressed in mature colonies (PubMed:10671449). Can be nitrosylated by NO, 8 NO react per cluster. These complexes are quite stable under anaerobic conditions, but degrade slowly aerobically. Upon Fe-S cluster removal intramolecular disulfide bonds are formed. Forms white aerial mycelium. Sporulation is reduced, spores are heat sensitive, lyse frequently and highly irregular in size. Septum placement and spore cell wall thickness is irregular. Belongs to the WhiB family.