FIG. 6.

Model for nutrient- and Ca²⁺-DPA-induced spore germination. Nutrients activate receptors, and this results in the release of core Ca²⁺-DPA, which then triggers CwlJ action. SleB action may be triggered by both the receptor activation and changes in the properties of the spore core-cortex as a result of Ca²⁺-DPA release, but Ca²⁺-DPA does not activate SleB directly. SleB and CwlJ then catalyze cortex hydrolysis, which is sufficient for germination. External Ca²⁺-DPA might induce germination by triggering CwlJ-dependent cortex hydrolysis, which would be amplified by the consequent release of core Ca²⁺-DPA, as shown by the dashed arrow.