FIG. 10.

Detection of polymer bundles by fluorescence microscopy. Purified native FtsZ (6.0 μM) was incubated in the presence of GTP (1 mM) and Mg²⁺ (10 mM) at 30°C. After 5 min, purified H-T-ZipA(39–328)-Gfp was added to 0.6 μM. After an additional 10 min, one sample was applied to a microscope slide and observed immediately by fluorescence microscopy (A) and another was used for observation by EM (B). The fluorescent samples shown in panels C to F were prepared identically, except that GTP was replaced with GDP (C), FtsZ was replaced with buffer (D), or H-T-ZipA(39–328)-Gfp was replaced with either Gfp-T-ZipA(186–328)-H (E) or Gfp-T-ZipA(212–328)-H (F). EM grids prepared from the reactions shown in panels C to F showed extensive bundle networks as in panel A (E), no bundles but many individual FtsZ protofilaments (F), or no individual protofilaments or polymer bundles (C and D) (data not shown). Bar, represents 0.1 μm (B) or 3.4 μm (A and C to F).