Application of NMR to study the polymerization mechanism of FtsZ and its inhibition by natural and synthetic modulators

Abstract

The cell division process - cytokinesis - in bacteria occurs by binary fission through a molecular machine called divisome. The divisome is a protein complex that acts coordinately to form the division septum. Among these proteins, FtsZ, a cytoplasmic GTPase, is a key protein in the cytokinesis process. FtsZ polymerizes and forms the Z ring, a protein scaffold that organizes and initiates the division process. FtsZ is a bacterial homologue of tubulin and is universally conserved in bacteria. The FtsZ tertiary structure is similar to tubulin´s, showing two globular domains separated by a long central helix. The N-terminal domain harbors the nucleotide's binding site; however, its GTPase activity only occurs in the polymeric form. FtsZ polymers are highly dynamic: GTP binding promotes longitudinal monomer association forming protofilaments and GTP hydrolysis leads to depolymerization. Several divisome proteins act as positive or negative modulators of FtsZ, promoting the assembly of FtsZ to form the Z ring or inhibiting FtsZ polymerization and cell division. These regulatory proteins play a central role in the spatial and temporal control of cell division but their mechanism of action is still poorly understood at the structural level. Since FtsZ is essential for cell division, widely conserved among prokaryotes and is evolutionarily distant from tubulin, it is pointed as a good target for the design of new antibiotics with selectivity to bacterial infections treatment. Therefore, herein we focus on this protein, using a structural approach based on NMR experiments. We intend to characterize the conformational and protein dynamic changes associated with FtsZ polymerization. In addition, we intend to map the interactions of FtsZ with negative modulators, both proteins and small molecules, by NMR. Moreover, we plan to set up a powerful and selective method for the screening of new cell division inhibitors.