Figure 7.

Effects of mutations on ring formation and FtsZ binding. (A) Size exclusion chromatography of the different SepF mutants using an analytical Superose 6 column. The absorbance at 280 nm (AU) is plotted as a function of the elution volume. The peaks of two reference proteins thyroglobulin (T, 669 kDa) and aldolase (A, 158 kDa) are indicated by arrows. SepF has a calculated size of 17 kDa. (B) EM images of negatively stained SepF mutants. Scale bar is 50 nm (buffer used; 20 mM Tris–HCl pH 7.4, 200 mM KCl, 5 mM MgCl₂). (C) Western blot analyses of a SepF–FtsZ co-elution experiment using different MBP–SepF mutants. The columns were incubated with (+) or without (−) B. subtilis FtsZ. FtsZ-antiserum was used to stain the blots (see Materials and methods, for details).