Genotype, phenotype, and protein structure in a regulator of sporulation: Effects of mutations in the spoIIAA gene of Bacillus subtilis

SpoIIAA, a phosphorylatable protein, is essential to the regulation of sigm a(F), the first sporulation-specific transcription factor of Bacillus subti lis. The solution structure of SpoIIAA has recently been published. Here we examine four mutant SpoIIAA proteins and correlate their properties with t he phenotypes of the corresponding B. subtilis mutant strains. Two of the m utations severely disrupted the structure of the protein, a third greatly d iminished the rate of its phosphorylation and abolished dephosphorylation, and the fourth left phosphorylation unaffected but reduced the rate of deph osphorylation about 10-fold.