Crystallization and preliminary X-ray analysis of the sporulation factor SpoIIAA in its native and phosphorylated forms

Sporulation in Bacillus begins with an asymmetric cell division producing two progeny with identical chromosomes but different developmental fates. As such, it is a simple example of cellular differentiation. The establishment of cell type is controlled by a series of alternate RNA polymerase sigma subunits. The first compartment-specific sigma factor is σ^F, whose activity is controlled by SpoIIAB, an anti-sigma factor, and SpoIIAA, an anti-sigma factor antagonist which is phosphorylated by the kinase activity of SpoIIAB. Here, the preliminary crystallographic analysis of SpoIIAA and phosphoryl­ated SpoIIAA from B. sphaericus in forms suitable for high-resolution structure determination are reported.