Role of the Sporulation Protein BofA in Regulating Activation of the Bacillus subtilis Developmental Transcription Factor ς K

During sporulation, the Bacillus subtilis transcription factor sigmaK is activated by regulated proteolytic processing. I have used a system that facilitates the analysis of the contributions of a modified form of the processing enzyme, SpoIVFB-GFP, and the regulatory proteins BofA and SpoIVFA to the conversion of pro-sigmaK to sigmaK. The results show that in the presence of BofA, SpoIVFA levels increase by greater than 20-fold, SpoIVFA is substantially stabilized, and pro-sigmaK processing is inhibited. In addition, enhanced accumulation of the SpoIVFA protein in the absence of BofA (achieved through the use of an ftsH null mutation) substantially inhibits pro-sigmaK processing. These results suggest that during growth, increased accumulation of the SpoIVFA protein inhibits the activity of SpoIVFB-GFP and regulates the activation of sigmaK.