Vinblastine induces an interaction between FtsZ and tubulin in mammalian cells

The Escherichia coli cell division protein FtsZ was expressed in Chinese ha mster ovary cells, where it formed a striking array of dots that were indep endent of the mammalian cytoskeleton, Although FtsZ appears to be a bacteri al homolog of tubulin, its expression had no detectable effects on the micr otubule network or cell growth. However, treatment of the cells with vinbla stine at concentrations that caused microtubule disassembly rapidly induced a network of FtsZ filaments that grew from and connected the dots, suggest ing that the dots are an active storage form of FtsZ, Cells producing FtsZ also exhibited vinblastine- and calcium-resistant tubulin polymers that col ocalized with the FtsZ network. The FtsZ polymers could be selectively disa ssembled, indicating that the two proteins were not copolymerized, The vinb lastine effects were readily reversible by washing out the drug or by treat ing the cells with the vinblastine competitor, maytansine. These results de monstrate that FtsZ assembly can occur in the absence of bacterial chaperon es or cofactors, that FtsZ and tubulin do not copolymerize, and that tubuli n-vinblastine complexes have an enhanced ability to interact with FtsZ.