FIG. 3.

Map of the activating region of Spo0A proposed for ς^A-dependent transcription. The Spo0A protein consists of two domains. The phosphoacceptor domain is formed by the N-terminal 127 aa, and the effector domain is formed by the C-terminal 113 residues; they are joined by a linker region of 27 aa, as defined by Brown et al. (7). Mutations in Spo0A protein which decrease activation of ς^A-dependent promoters under Spo0A control described in this work and elsewhere (8) are mapped. Residues examined in this study are in boldface. The ς^A activating region (ς^A AR) (solid bar) includes residues from aa 227 to aa 240. The K265 residue may also have some effect on transcription activation of ς^A-dependent promoters. Also indicated is position A257, which, when mutated, generates the spo0A9V mutant, which does not activate transcription of ς^H-dependent promoters (28). Shaded bar, putative DNA binding domain (aa 194 to 224) proposed for Spo0A based on sequence conservation of this region in spo0A homologs from diverse Bacillus and Clostridium species (7).