Synthesis of the ς(D) Protein Is Not Sufficient To Trigger Expression of Motility Functions in Bacillus subtilis

The gene encoding ς(D), sigD, is transcribed from two promoter regions, the fla/che promoter region in front of the fla/che operon and P(sigD) directly in front of sigD. If ς(D) is translated from transcripts originating from P(sigD), the cell is unable to express motility functions but synthesizes autolysins. Therefore, one function of the additional promoter is to allow the cell to express autolysins without expressing motility functions as well.