Kinetic Modeling of the Assembly, Dynamic Steady State, and Contraction of the FtsZ Ring in Prokaryotic Cytokinesis
Figure 12
Flux and Energy Dynamics Associated with Model Behavior.
(A) Assembly: long open FtsZ polymers are produced by elongation, which then cyclize into closed ring structure – Z ring. (B) Dynamic steady state: hydrolysis followed by fragmentation leads to opening of the ring which is then restored by addition of one monomer followed by cyclization. Also ring appears to be stable, with constant breaking/closing of the ring in the system. (C) Contraction: hydrolysis again results in an open polymer one subunit shorter, but since elongation is inhibited now, this is followed by cyclization at a suboptimal polymer length. This results in a ring one subunit shorter than before this process. (D) Energetics of contraction: the energy of GTP hydrolysis is released in several steps, including self-assembly into open polymers, cyclization resulting in closed structures, and expulsion of GDP-FtsZ from polymer chains. Cyclization is coupled to membrane constriction.