Sporulation protein SpoIVFB from Bacillus subtilis enhances processing of the sigma factor precursor pro-σ(K) in the absence of other sporulation gene products

Processing of inactive pro-σ(K) to active σ(K) in the mother cell compartment of sporulating Bacillus subtilis is governed by a signal transduction pathway emanating from the forespore and involving SpoIVFB in the mother cell. Coexpression of spoIVFB and sigK (encoding pro-σ(K)) genes in growing B. subtilis or Escherichia coli enhanced pro-σ(K) processing in the absence of other sporulation-specific gene products. The simplest explanation of these results is that SpoIVFB is a protease that processes pro-σ(K).