Fig. 1.

Two dynamin-like proteins are important for sporulation-specific cell division. (A) Schematic depicting the Streptomyces life cycle starting with a spore that germinates and grows into a vegetative mycelium, followed by the formation of a reproductive hypha that differentiates into a chain of equally sized spores. FtsZ associated with vegetative cross-walls and sporulation septa is shown in blue. (B) Schematic showing the predicted domain organization of DynA and DynB. The GTPase domain is shown in orange and transmembrane helices (M) are shown in black. Numbers indicate corresponding amino acid positions. (C) Fractionation experiment using S. venezuelae strains expressing either a functional dynA-3xFLAG (SS93, left lane) or a dynB-3xFLAG (SS140, right lane) fusion from the ΦBT1 attachment site. Whole-cell lysates were separated into soluble and membrane fractions and probed with anti-FLAG antibody. The asterisk denotes a nonspecific signal in the soluble protein fraction. Shown are representative results of biological replicate experiments. (D) Scanning electron micrographs of sporogenic hyphae from wild-type S. venezuelae (WT) and the dynamin mutant (ΔdynAB). (Scale bars: 2 μm.) (E) Transmission electron micrographs of sporogenic hyphae from the WT and ΔdynAB mutant. Black arrowheads indicate failed and asymmetric constrictions in the dynamin mutant. (Scale bars: 500 nm.) (F) Box plot showing the length distribution of spores produced by the WT (n = 1,113), the ΔdynAB mutant (n = 676) and the complemented dynamin mutant (SS23, n = 612). Whiskers denote the 5th and 95th percentile.