The influence of membrane-free microcompartments resulting from crowding-induced 
liquid/liquid phase separation (LLPS) on the dynamic spatial organization of 
FtsZ, the main component of the bacterial division machinery, has been studied 
using several LLPS systems. The GTP-dependent assembly cycle of FtsZ is thought 
to be crucial for the formation of the septal ring, which is highly regulated in 
time and space. We found that FtsZ accumulates in one of the phases and/or at 
the interface, depending on the system composition and on the oligomerization 
state of the protein. These results were observed both in bulk LLPS and in 
lipid-stabilized, phase-separated aqueous microdroplets. The visualization of 
the droplets revealed that both the location and structural arrangement of FtsZ 
filaments is determined by the nature of the LLPS. Relocation upon 
depolymerization of the dynamic filaments suggests the protein may shift among 
microenvironments in response to changes in its association state. The existence 
of these dynamic compartments driven by phase transitions can alter the local 
composition and reactivity of FtsZ during its life cycle acting as a nonspecific 
modulating factor of cell function.