Figure 1.

Externally added c-di-AMP promotes progression of sporulation. (A) The chemical structure of c-di-AMP. (B) Fluorescence microscopy images of PY79 (wild-type) cells at 2 h of sporulation in the absence (–) and presence (+) of c-di-AMP (1.4 μM) added at 0 h. Cells were treated with the membrane stain FM1-43. Arrows indicate, positions of polar septa. Scale bar, 1 μm. (C) The percentage of sporulating PY79 (wild-type) and YA5 (ΔdisA) cells at 2 h of sporulation in the absence and presence of c-di-AMP or c-di-GMP (1.4 μM) added at 0 h. (D) The percentage of sporulating PY79 (wild-type) cells at 2.5 h of sporulation in the absence and presence of c-di-AMP (1.4 μM) and various concentrations of nalidixic acid as indicated. c-di-AMP and nalidixic acid were added at 0 h. (C,D) Cells were visualized using fluorescence microscopy, with the appearance of polar septa serving as the marker of sporulation. One representative experiment out of three independent experiments is shown. Standard deviation was calculated from the means of several fields of cells. At least 600 cells were counted for each treatment. c-di-AMP, cyclic diadenosine monophosphate; c-di-GMP, bis-(3’–5’)-cyclic dimeric guanosine monophosphate.