Indeed, when divIB selleck kinase inhibitor mutant cells were shifted to the higher temperature, cells elongated markedly (compare Figure 1G and 1I), which was also true for dynA divIB double mutant cells, whose length could not easily be distinguished by eye from the divIB single mutant strain, neither at 30°C (Figure 1H) nor at signaling pathway 42°C (Figure 1J). We measured average cell length for 140 to 150 cells for each strain and for each growth temperature, from 3 independent experiments. The average cell length of divIB mutant cells was 4.03 μm (1.4 μm standard deviation, SD) at 30°C and 5.15 μm (4.9 μm SD) at 42°C, while that of dynA divIB mutant
cells was 3.9 μm (1.2 μm SD) at 30°C and 6.18 μm (5.15 μm SD) at 42°C. Average cell length of dynA mutant cells at 42°C was 3.75 μm Selleck JNK-IN-8 (1.1 μm SD). The high standard deviation at 42°C stems from the fact that a considerable number of cells were extremely long (up to 25 μm), while most cells had a size below 5 μm. To account for this, we grouped cells into three categories: cells below 5.5 μm, cells between 5.5 and 10 μm, and cells above 10 μm. For divIB single mutant cells, 6.3% of the cells were above 5.5 μm long, and 0.7% above 10 μm at 30°C, while at 42°C, 19% were above 5.5 μm and 8% above 10 μm. At 30°C, 8.5% of double mutant cells were above 5.5 μm and 1.5% above 10 μm, and at 42°C, 34% were above 5.5 μm
and 12% above 10 μm (Table 1). Thus, the fraction of double mutant cells was higher in each of the “large cell” categories compared with the single divIB mutant cells. Single and double mutant cells contained normally segregated nucleoids (Figure 1G-J), showing
that cell elongation is not an effect of delayed or blocked chromosome segregation. These data show that the deletion of a late cell division gene also exacerbates the dynA phenotype, showing that DynA does not only affect a step in cell division that is specific to the activity of EzrA. Table 1 Distribution of cell length in single and double mutant cells <5.5 μm >5.5 μm <10 μm >10 μm ΔdivIB 30°C 93% 6.3% 0.7% ΔdynA ΔdivIB 30°C 90% 8.5% 1.5% ΔdivIB 42°C 73% 19% 8% ΔdynA ΔdivIB 42°C 64% 34% 12% DynA co-localizes Demeclocycline with FtsZ and affects the formation of the Z ring We generated a dynA(ypbR)-yfp fusion that was integrated into the original gene locus. Cells expressing DynA-YFP did not show any double septa, or highly elongated cells, indicating that the fusion can functionally replace the wild type protein and/or any of the possible post-translationally modified versions of DynA. Western blot analysis showed that full length DynA-YFP is expressed at extremely low levels, as well as a C-terminal fragment of 27 kDa and several smaller fragments (Figure 2, note that YFP is 28 kDa, giving rise to a band of 55 kDa).