Benzodioxane-benzamides targeting bacterial cell division protein FtsZ potentially disrupt SlmA-mediated nucleoid occlusion and reversible biomolecular condensation.

New strategies are urgently needed against antimicrobial resistance, a major health threat, and the different mechanisms regulating the bacterial cell division machinery offer multiple opportunities for developing novel therapeutics. FtsZ, an essential protein of this process, is targeted by multiple small molecules, and benzodioxane-benzamides (BDOBs) are among the most potent inhibitors in several bacterial species. BDOBs mechanisms are however poorly understood, particularly their impact on FtsZ's interplay with partners and ability to assemble phase-separated biomolecular condensates potentially involved in stress sensing. We show that certain BDOBs shielded FtsZ against depolymerization induced by the nucleoprotein complexes of SlmA, which inhibit Z-ring formation near the nucleoid. In crowding cytomimetic conditions, BDOBs disrupted the canonical interconversion between FtsZ-SlmA condensates and polymers in response to GTP levels. Our results strongly suggest that BDOBs interfere with normal regulation of Z-ring assembly by antagonists such as SlmA that protect important cellular structures like the nucleoid. Specifically, BDOBs may reduce the susceptibility of FtsZ polymers to SlmA and impair biomolecular condensates reassembly. We propose that fine tuning of the equilibrium between FtsZ polymers and biomolecular condensates is important for spatial regulation of Z-rings and stress resistance, and this equilibrium is subverted by BDOBs.