Figure 1.

SsgB and FtsZ colocalize during sporulation-specific cell division in S. coelicolor. (From left to right) SsgB, FtsZ, an overlay of the two, and the corresponding bright-field image. Developmental stages are shown as follows (for explanation, see the model in Fig. 9): early aerial hyphae (stage IIA; 0.6–0.7 μm in diameter) (top row); predivision foci in aerial hyphae (stage IIC; diameter, 0.8 μm) (middle row); Z rings (stage III; diameter, 0.9 μm) (bottom row). SsgB localizes when ftsZ is still diffusely distributed, while, at later stages, including Z-ring formation, they fully colocalize. See also Figure 4. The approximate developmental stages were determined on the basis of their position in the mycelium (proximity to the vegetative hyphae) and the width of the hyphae (ranging from ∼600 nm for emerging aerial hyphae to ∼900 nm [i.e., spore width] for sporulating aerial hyphae). Note that, for all stages, images were obtained for both combinations of SsgB-eGFP + FtsZ-mCherry (S. coelicolor JSC2) and SsgB-mCherry + FtsZ-eGFP (S. coelicolor JSC3), with the top row presenting JSC2, and the middle and bottom rows presenting JSC3. Most representative images are shown (mCherry fusions are shown in red, and GFP fusions are in green). Bar, 1 μm.