Biochemical characterization of two trimers of the bacterial cell division protein (FtsZ) from E. coli

Abstract

FtsZ is a bacterial divisome protein responsible for Z-ring formation in cytokinesis. Characterization of Escherichia coli FtsZ protein oligomers (EcFtsZ) in native conditions is defiance because the protein is found as a multi-oligomer in self-association-dissociation equilibrium. We characterize the trimeric state of EcFtsZ through native PAGE, gel filtration chromatography and sucrose gradient techniques combined with chemical cross-linking. The filtration results indicate that the EcFtsZ trimer has a molecular mass of 131 kDa and a filtration friction coefficient (Rs/Rmin) equal to 1.9, while the theoretical filtration friction coefficient (fn/f1) calculated for a linear trimer yielded a value equal to 1.8 very close to the experimental value. On the other side, formaldehyde-crosslinked EcFtsZ showed a band 128 kDa recognized by anti-FtsZ antibodies, and a sedimentation friction coefficient (Smax/S20,w) equal to 1.9, while the theoretical sedimentation friction coefficient (Sn/S1) calculated for a triangular trimer was equal to the experimental value. These results suggest that EcFtsZ has two homotrimeric structures (linear and triangular). Finally, we report the aggregation of EcFtsZ at micromolar concentrations of Capsaicin without GTP and Mg2+.