title: Mg(2+)-linked self-assembly of FtsZ in the presence of GTP or a GTP analogue involves the concerted formation of a narrow size distribution of oligomeric species.
abstract: The assembly of the bacterial cell division FtsZ protein in the presence of constantly replenished GTP was studied as a function of Mg(2+) concentration (at neutral pH and 0.5 M potassium) under steady-state conditions by sedimentation velocity, concentration-gradient light scattering, fluorescence correlation spectroscopy, and dynamic light scattering. Sedimentation velocity measurements confirmed previous results indicating cooperative appearance of a narrow size distribution of finite oligomers with increasing protein concentration. The concentration dependence of light scattering and diffusion coefficients independently verified the cooperative appearance of a narrow distribution of high molecular weight oligomers, and in addition provided a measurement of the average size of these species, which corresponds to 100 ± 20 FtsZ protomers at millimolar Mg(2+) concentration. Parallel experiments on solutions containing guanosine-5'-[(α,β)-methyleno]triphosphate, sodium salt (GMPCPP), a slowly hydrolyzable analogue of GTP, in place of GTP, likewise indicated the concerted formation of a narrow size distribution of fibrillar oligomers with a larger average mass (corresponding to 160 ± 20 FtsZ monomers). The closely similar behavior of FtsZ in the presence of both GTP and GMPCPP suggests that the observations reflect equilibrium rather than nonequilibrium steady-state properties of both solutions and exhibit parallel manifestations of a common association scheme.
authors.affiliation: Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
authors.forename: Begoña
authors.initials: B
authors.lastname: Monterroso
authors.forename: Rubén
authors.initials: R
authors.lastname: Ahijado-Guzmán
authors.forename: Belén
authors.initials: B
authors.lastname: Reija
authors.forename: Carlos
authors.initials: C
authors.lastname: Alfonso
authors.forename: Silvia
authors.initials: S
authors.lastname: Zorrilla
authors.forename: Allen P
authors.initials: AP
authors.lastname: Minton
authors.forename: Germán
authors.initials: G
authors.lastname: Rivas
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000378:metabolism*; D057446:Hydrodynamics; D008027:Light; D008274:Magnesium / Q000378:metabolism*; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence
chemical_list: D001426:Bacterial Proteins; D003598:Cytoskeletal Proteins; C071525:FtsZ protein, Bacteria; D006160:Guanosine Triphosphate; D008274:Magnesium