FtsZ dimerization in vivo

A hybrid assay, based on the properties of the lambda repressor, was develo ped to detect FtsZ dimerization in Escherichia coil in vivo. A gene fusion comprising the N-terminal end of the lambda cl repressor gene and the compl ete E. coil ftsZ gene was constructed. The fused protein resulted in a func tional lambda repressor and was able to complement the thermosensitive muta nt ftsZ(84). Using the same strategy, a series of 10 novel mutants of FtsZ that are unable to dimerize was selected, and a deletion analysis of the pr otein was carried out. Characterization of these mutants allowed the identi fication of three separate FtsZ portions: the N-terminal of about 150 amino acids; the C-terminal of about 60 amino acids, which corresponds to the le ss conserved portion of the protein; and a central region of about 150 resi dues. Mutants belonging to this region would define the dimerization domain of FtsZ.