Figure 9.

Engulfment machineries in C. difficile. Proposed organization of the DP and Q:AH engulfment machineries. SpoIID (D, dark pink) interacts strongly with SpoIIQ (Q, blue) and weakly with SpoIIP (P, purple) and SpoIIIAH (AH, orange). SpoIIP is anchored to the forespore membrane and establishes weak interactions with SpoIIQ and SpoIID. The role of SpoIIM (M, pink) is unclear, as it seems to be dispensable for engulfment in C. difficile and only interactions with SpoIID have been detected. In this new model, Q:AH could act as anchor for the DP machinery, with both systems contributing to keeping the two‐membrane system tightly together throughout engulfment. Q:AH is shown as a channel‐forming complex as proposed by Meisner et al. (2012) and Levdikov et al. (2012), although the existence of this pore has not been unambiguously demonstrated to date.