# FtsZ Interactions and Biomolecular Condensates as Potential Targets for New Antibiotics
## 6 Could FtsZ Biomolecular Condensates Help Understand Persisters?
Drug candidates that modulate the formation of these structures may alter cell functionality and, more importantly, they may lead to novel strategies to combat persistence, a major health threat. The assays so far developed to study FtsZ biomolecular condensates would help to identify such candidates. Confocal fluorescence microscopy imaging has been an invaluable tool for the identification and characterization of FtsZ biomolecular condensates in crowding solutions in bulk and in cytomimetic systems [42; 43]. In those studies, confocal microscopy measured the size and shape of condensates formed by the scaffold biomolecules. Time-lapse confocal imaging monitored the conversion of FtsZ condensates to GTP-induced filaments and back, as well as the capture of client molecules from colocalization analysis, confirming their dynamism. Those studies also measured turbidity over time, which provided more quantitative information about the factors affecting condensate formation and permitted simultaneous evaluation of dozens of samples using a plate reader. Parallel measurements by confocal imaging and  
Figure 4: Hypothetical role of FtsZ biomolecular condensation in bacterial resistance to antibiotic treatment. Bacteria can survive antibiotics through a subpopulation of transiently tolerant persister cells or by genetically acquired resistance. The mechanisms leading to formation of persisters remain unclear, but the biomolecular condensates formed by FtsZ, by itself or with partners, may play a role. Homotypic and heterotypic phase-separated condensates of FtsZ-GDP are favored by multivalent interactions and crowding in cells. Condensates would be also favored in situations with low GTP levels, such as stress conditions leading to the activation of (p)ppGpp signaling after antibiotic exposure. The reversible conversion of FtsZ condensates into FtsZ polymers, triggered by GTP, would explain how the persister cells resume growth after stress conditions are over and normal GTP levels are restored. turbidity provided valuable information about how crowding, protein and nucleic acid concentration, salt and divalent cations fine tune condensate assembly by FtsZ [42; 43]. Reconstruction in lipid-stabilized microdroplets was also conducted in the aforementioned studies to get some insight into the spatial distribution of the FtsZ condensates in a confined and compartmentalized cell-like environment. Synthetic biology approaches are very promising for the investigation of biomolecular condensates involving bacterial factors because the visualization and tracking of condensates in cells as small as bacteria pose a significant challenge. The described methodologies provide a good starting point for the screening of molecules that deregulate condensate assembly, block evolution towards filaments in response to nucleotide, or modulate FtsZ condensate dynamics and spatial distribution in cell-like systems. The growing number of methodologies that are currently being applied or adapted to the study of biomolecular condensates [156] provide an excellent opportunity to devise additional assays for these FtsZ assemblies. Among the techniques previously applied to study FtsZ interactions, FCS [157] and DLS [158] have been recently used to analyze biomolecular condensates. Other research directions towards the possible exploitation of FtsZ condensates as targets would involve whether they can be promoted by cell division proteins other than SlmA and the identification of condensates formed by FtsZ from other species.