Processing of DynA into two dynamin-like #NVP-HSP990 randurls[1|1|,|CHEM1|]# proteins (it consists of two fused dynamin modules) would give rise to 62 to 63 kDa sized proteins, which would be 90 kDa when
fused to YFP. This is not the case according to the Western blot analysis. It is unclear if the truncation product is generated through the YFP fusion construct, or also occurs for wild type DynA. Therefore, localization studies must be viewed in light of the caveat that the truncation product may confer some level of DynA activity. Figure 2 Western blot of exponentially growing cells expressing DynA (PY79) or DynA-YFP as indicated above the lanes, using anti GFP antiserum. Filled triangle corresponds to full length DynA-YFP, open triangle a C-terminal 27 kDa fragment of DynA plus YFP. Note that the band at 50 kDa is a crossreaction seen with the serum. DynA-YFP localized to the cell center in exponentially growing cells (Figure 3A), and formed one or two foci at irregular places along the membrane in 15% of the cells (Figure 3B, 200 cells analyzed). Thus, in contrast to e.g. the membrane protein
MreC, which localises as distinct foci throughout the membrane (Figure see more 3C, note that there are two adjacent membranes at the division septum), DynA is clearly highly enriched at the future division site. Indeed, DynA-YFP co-localized with FtsZ-CFP (Figure 3A); clear DynA-YFP fluorescence was seen at 85% of FtsZ-CFP rings, and 15% of Z rings were devoid of detectable DynA-YFP fluorescence (250 cells analysed), which, however, was extremely faint. Many cells contained DynA-YFP foci rather than ring-like structures (Figure 3A, indicated by white triangle). These data indicate that DynA is recruited to the Z ring, possibly at an early time point during cell division. Figure 3 Localization of DynA, FtsZ, FloT and MreB. A-B) Growing wild type cells expressing DynA-YFP and FtsZ-CFP, white lines indicate septa between cells, overlay: FtsZ-CFP in red, DynA-YFP
in green, Ureohydrolase C) cells expressing YFP-MreC, D) stationary phase cells expressing DynA-YFP, white triangles indicate membrane-proximal foci, E) dynA (ypbR) mutant cells expressing FtsZ-CFP, white triangles indicate asymmetric FtsZ rings, grey triangles large cells lacking FtsZ rings but instead containing membrane-proximal accumulations of FtsZ-CFP: white lines indicate septa between cells, F) wild type cells expressing FloT-YFP, overlay with membranes (red) and FloT-YFP (green), G) floT mutant cells expressing DynA-YFP. H) dynA mutant cells expressing FloT- YFP, time lapse with images taken every 2 s. White or grey bars 2 μm. During stationary phase, many cells showed multiple DynA-YFP foci, while most cells (60%) did not reveal any focus (Figure 3D).