Fig 7. Model of Spo0E influence on sporulation initiation in C. difficile.

During exponential growth, Spo0E binds Spo0A and RstA, preventing Spo0A activation of sporulation, and promoting RstA repression of toxin and motility genes (PflgB, PtcdR, PtcdA, PtcdB). At the transition to stationary phase, RstA is predicted to bind a quorum sensing peptide (♦), resulting in confirmational changes that prevent Spo0E protein-protein interactions. This leads to derepression of toxin and motility genes and the phosphorylation of Spo0A, resulting in sporulation.