GTP regulates the interaction between MciZ and FtsZ: a possible role of MciZ in bacterial cell division.

MciZ, a peptide with 40 amino acid residues, has been shown to be expressed during bacterial sporulation, to inhibit Z-ring formation in bacteria, and to inhibit the assembly of FtsZ in vitro. Here, MciZ was found to bind to FtsZ in vitro with a dissociation constant of 0.3 ± 0.1 μM. Guanosine nucleotides inhibited the binding of MciZ to FtsZ; however, GTP inhibited the binding of MciZ to FtsZ more strongly than GDP. In addition, MciZ inhibited the binding of 2',3'-O-(2,4,6-trinitrocyclohexadienylidene)-GTP, a fluorescent analogue of GTP, to FtsZ. The results indicated that MciZ shares its binding site on FtsZ with GTP. Furthermore, M19I, an N-terminal 19-residue peptide (MKVHRMPKGVVLVGKAWEI) of MciZ, inhibited the assembly and GTPase activity of FtsZ in vitro. The results suggested that GTP plays an important role in the regulation of the interaction between FtsZ and MciZ and that M19I may be used as a lead peptide to design peptide inhibitors of FtsZ assembly.