ZipA prevented dilution-induced disassembly of FtsZ polymers.

FtsZ (25 µM) was polymerized as described in the materials and methods section. The preformed FtsZ polymers were diluted 20 times in warm 25 mM PIPES buffer, pH 6.8 without and with different concentrations of ZipA and incubated for an additional 5 min at 37°C. The polymers were collected through centrifugation and the amount of FtsZ in the pellet was estimated using Coomassie blue stained SDS-PAGE. Lanes 1–5 denote FtsZ polymers pelleted in the absence and presence of 1, 2, 3 and 4 µM ZipA, respectively (Panel A). The relative amount of FtsZ in the pellets with respect to control was plotted against ZipA concentration (Panel B).