ACTIVATION OF CELL-SPECIFIC TRANSCRIPTION BY A SERINE PHOSPHATASE AT THE SITE OF ASYMMETRIC DIVISION

Cell fate is determined by cell-specific activation of transcription f actor sigma(F) after asym metric division during sporulation by Bacill us subtilis. The activity of sigma(F) is governed by SpoIIAA, SpoIIAB, and SpoIIE, a membrane protein localized at the polar septum. SpoIIAB binds to and inhibits of, and SpoIIAA inhibits SpoIIAB, which prevent s SpoIIAB from binding to sigma(F). SpoIIAB is also a serine kinase th at inactivates SpoIIAA. Here, it is demonstrated that SpoIIE dephospho rylates SpoIIAA-P and overcomes SpoIIAB-mediated inhibition of sigma(F ). The finding that SpoIIE is a serine phosphatase links asymmetric di vision to the pathway governing cell-specific gene transcription.