Extended Data Fig. 6: FtsZ1 and FtsZ2 fluorescent fusions are not fully functional as sole copies but at moderate concentrations have minimal impact on cell division in the wild type.
a-b, FtsZ1 and FtsZ2 fluorescent fusion proteins were functionally tested in their respective ΔftsZ1 or ΔftsZ2 backgrounds by phase-contrast and fluorescence microscopy (left) and by Coulter cytometry (right) for cell size. FtsZ1-GFP and FtsZ1-mCherry (0.2 mM Trp) partially complement ΔftsZ1. b, FtsZ2-GFP was unable to complement the ΔftsZ2 background, whereas the untagged protein achieves full complementation (0.2 mM Trp). The same dataset for the wild-type control is shown in both graphs as a reference. c-e, When expressed in wild-type cells, FtsZ1-mCherry or FtsZ2-GFP, or both, cause minimal effects on cell size and shape at a moderate level of expression (0.2 mM Trp), and show sharp midcell bands. These proteins are therefore useful localization markers for division, although detailed analyses of FtsZ subcellular ultrastructure and dynamics await the development of functional complete labelling. The data shown are representative of at least two independent experiments. Scale bars, 5 µm.
