Thus, DynA is associated with the cell division machinery in growing cells, in agreement with the observed phenotype of the dynA deletion, and remains membrane-associated in non-growing cells. The apparent effect on cytokinesis prompted us to study the localization of FtsZ in dynA mutant cells. Although Z rings were normally positioned at mid cell in most dynA mutant cells, several abnormal morphologies of Z rings were observed: a) Z rings that CB-5083 mouse appeared to be an open helix (Figure 3E, left panel), b) Z rings that were brighter

on one side (Figure 3E, right panel), c) double septa (not shown) and d) missing rings in very large cells (> 4 μm, Figure 3E, right panel), which in wild type cells invariably contain Z rings. These aberrant structures www.selleckchem.com/products/tpx-0005.html were seen in about 15% of dynA mutant cells (180 cells analysed), indicating that DynA

has an effect on the formation of a proper FtsZ ring, directly or indirectly, and that the defect in cell division arises largely through the loss of this function. A synthetic defect in cell division, cell shape maintenance and motility for dynamin and flotillin double mutant cells Eukaryotic membranes appear to have an asymmetric distribution of lipids, and specific proteins associated with the so-called lipid rafts. Flotillins are a divergent membrane protein family associated with lipid rafts, and are characterized by the SPFH domain of unknown function and extended heptad repeat regions [30]. B. subtilis Terminal deoxynucleotidyl transferase flotillin-like proteins FloT and YqfA are involved in the clustering of a signal transduction protein in the membrane [24], and in the timing of initiation of sporulation [31]. Eukaryotic flotillin proteins are involved in clathrin-independent endocytosis, and in other processes, where membrane bending is of importance [32]. We reasoned

that lipid rafts and bacterial dynamin may synergistically facilitate cell division, and therefore combined floT and dynA deletions. Strikingly, double mutant cells were highly elongated and showed a strong defect in cell shape maintenance (Figure 4A). Many cells were bent and had an irregular width, and a considerable fraction could reach a size of 12 μm. Frequently, cells showed aberrant membrane staining (Figure 4A), including large membrane perturbations. Although nucleoids were irregularly positioned, we did not observe any anucleate cells. In contrast to an smc mutant strain, in which chromosomes are highly decondensed and fill the entire cytoplasm (in which nucleoid occlusion blocks cell division [33]), floT/yprB double mutant cells contained many DNA-free sites in which nucleoid occlusion would not block division. However, cells were highly filamentous, suggesting that FloT and DynA synergistically affect cell division, in addition to an effect on rod-shape cell elongation. In agreement with the cytological data, the double mutant strain grew much slower than the wild type, and had a highly extended lag phase (Figure 5).