However, 5.5% of the cells showed double septa/mini cells (Figure 1B), which are never observed in wild type cells (Figure 1A). Additionally, 2.5% of mutant cells were larger than 5.5 μm (Figure 1C), while only 0.5% of wild type cells reach this size (250 cells measured for each strain). In contrast to e.g. a deletion of sftA, encoding for a DNA translocase that couples late states of chromosome segregation and cell division [25, 26], DNA was never observed to be trapped in a closed selleck screening library division septum in dynA mutant cells. Therefore, chromosome

segregation occurs normally in the mutant cells, but cell division is noticeably defective. Figure 1 Phenotypes of exponentially growing wild type (PY79) or mutant Bacillus subtilis cells. A) Wild type cells, B) dynA (ypbR) mutant cells, white triangles indicate double septa, C) dynA (ypbR) mutant cells, grey triangle

indicates highly elongated cell, D) ezrA mutant cells, E) ezrA/dynA double mutant cells, F) ezrA/dynA double mutant cells, white triangles indicate double septa, G) divIB mutant cells grown at 30°C, H) divIB/dynA double mutant cells grown at 30°C, I) divIB mutant cells grown at 42°C, J) divIB/dynA double mutant cells grown at 42°C. White or grey bars 2 μm. We wished to investigate the effect of a combination of the dynA deletion with that find more of a protein known to be important for an initial step in cell division. EzrA is a regulator of FtsZ, and therefore acts at a very early time point during cell division. The deletion of ezrA leads to the generation of elongated cells, to the formation of double septa and mini cells in rich medium [27]. In minimal medium used in this study, ezrA mutant cells were elongated, and formed mini cells (9%), but did not show any double septa (Figure 1D). Interestingly, ezrA dynA double mutant cells were more elongated than ezrA single mutant cells (Figure 1E), and contained more double septa than both single mutants (Figure 1F). Double mutant cells measured on average 5.16 ± 0.5 μm versus 4.07 ± 0.45 4-Aminobutyrate aminotransferase μm for ezrA

mutant cells, and contained double septa in 15% of the cells versus 5% in dynA single mutant cells (with 200 cells measured for each strain from 2 independent check details experiments). Occasionally, long ezrA dynA double mutant cells showed a single condensed or decondensed nucleoid indicating a segregation defect, but this referred only to a subpupulation of long cells (Figure 1E, white triangle). Thus, the increase in cell length is largely due to an effect on cell division. These data suggest that EzrA and DynA affect two distinct steps early in cell division, each of which contributes to efficient cell division, because all phenotypes are exacerbated by the loss of both proteins. We also tested if the dynA deletion is affected by the deletion of a gene involved in a later step of cell division. We used divIB mutant cells, which show a pronounced defect in cell division when they are shifted from 30 to 42°C.