Fig. 1.
Asymmetric cell division, σF activation and the role of SpoIIE. (a) In the pre-divisional cell (not shown) and the mother cell following cell division (left), SpoIIAA (AA) is phosphorylated and σF is in a complex with SpoIIAB (AB2). SpoIIE (E) accumulates at the asymmetric septum, a double-membrane structure. In the forespore (right), σF is free and AA and AB are in complex. The two cells are surrounded by a layer of cell wall (shaded). (b) The structures of SpoIIAA∼ P (left) and SpoIIAA (right) and their interconversion by phosphorylation by SpoIIAB and dephosphorylation by SpoIIE. This and subsequent structure figures were prepared in the program CCP4MG.50 (c) The putative three-domain structure of SpoIIE. The limits of the putative FtsZ binding domain are uncertain.