Epulopiscium engulfment model. The Epulopiscium genome codes for all of the genes known to be essential for engulfment in B. subtilis, except spoIIM and spoIIQ which are also absent in C. lentocellum. A) SpoIID and SpoIIP assemble into a complex (red ovals) at the division septum and degrade the septal peptidoglycan. B) As the mother-cell membrane wraps around the offspring, the IIDP complex tracks along the leading edge where it is involved in interactions with the mother-cell peptidoglycan and synthesis of offspring cell wall. C) When it reaches the cell tip, membrane fusion is mediated by SpoIIIE (yellow circle). During engulfment, SpoIIIAH (green rectangles) produced in the mother cell and a hypothetical protein (blue rectangles) from the offspring cell bind and prevent backward movement of the mother-cell membrane. In this diagram, black lines indicate membranes and grey peptidoglycan.