Multi-functional regulator MapZ controls both positioning and timing of FtsZ polymerization

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• FtsZ (filamenting temperature-sensitive mutant Z) forms the cytokinetic ring essential for bacterial cell division.
• Precise regulation of FtsZ assembly and positioning is critical for producing identical daughter cells.

Purpose of the Study:

• To investigate the interaction between MapZ (mid-cell-anchored protein Z) and FtsZ in *Streptococcus pneumoniae*.
• To elucidate the role of MapZ in regulating FtsZ polymerization dynamics and cell division timing.

Main Methods:

• Nuclear magnetic resonance (NMR) titration experiments were used to identify key interaction residues between MapZ-N (intracellular domain of MapZ) and FtsZ.
• Biochemical assays were performed to assess the effects of MapZ-N on FtsZ polymerization kinetics and GTP hydrolysis.

Main Results:

• MapZ-N directly interacts with FtsZ, influencing its polymerization.
• MapZ-N accelerates FtsZ activation, lowers its critical polymerization concentration, and increases GTP hydrolysis cooperativity.
• MapZ-N also antagonizes lateral FtsZ filament interactions, slowing bundle formation and maintaining FtsZ dynamics.

Conclusions:

• MapZ acts as a multi-functional regulator of FtsZ.
• MapZ controls both the precise positioning and the dynamic timing of FtsZ polymerization during cell division.
• These findings provide insights into the intricate mechanisms governing bacterial cytokinesis.