The Thermodynamic Study Of FtsZ

FtsZ is a prokaryotic homologue of eukaryotic cytoskeletal tubulin and is a key molecule in bacterial cell division. During bacterial cell division, FtsZ polymerizes into tubulin-like protofilaments by head-to-tail association. Then, the protofilaments assembles into a ring, called Z ring, which attaches to the membrane at the center of the bacterium. Subsequently, it recruits many accessory proteins that are also essential for cell division. Hydrolysis of guanosine triphosphate (GTP) bound to FtsZ protofilaments is thought to drive a straight-to-curved conformational change and generates the constrictive force required for cell division. Although multiple crystal structures of FtsZ in monomers and protofilaments are available,little is known about how the chemical energy converts to a mechanical constrictive force.Here we show that this constrictive force generation process occurs at a highly efficient way, based on thermodynamic measurements of guanosine triphosphate(GTP) or guanosine diphosphate(GDP) binding to FtsZ mutants using isothermal titration calorimetry(ITC).