title: MinC protein shortens FtsZ protofilaments by preferentially interacting with GDP-bound subunits.
abstract: The interaction of MinC with FtsZ and its effects on FtsZ polymerization were studied under close to physiological conditions by a combination of biophysical methods. The Min system is a widely conserved mechanism in bacteria that ensures the correct placement of the division machinery at midcell. MinC is the component of this system that effectively interacts with FtsZ and inhibits the formation of the Z-ring. Here we report that MinC produces a concentration-dependent reduction in the size of GTP-induced FtsZ protofilaments (FtsZ-GTP) as demonstrated by analytical ultracentrifugation, dynamic light scattering, fluorescence correlation spectroscopy, and electron microscopy. Our experiments show that, despite being shorter, FtsZ protofilaments maintain their narrow distribution in size in the presence of MinC. The protein had the same effect regardless of its addition prior to or after FtsZ polymerization. Fluorescence anisotropy measurements indicated that MinC bound to FtsZ-GDP with a moderate affinity (apparent KD ∼10 μM at 100 mm KCl and pH 7.5) very close to the MinC concentration corresponding to the midpoint of the inhibition of FtsZ assembly. Only marginal binding of MinC to FtsZ-GTP protofilaments was observed by analytical ultracentrifugation and fluorescence correlation spectroscopy. Remarkably, MinC effects on FtsZ-GTP protofilaments and binding affinity to FtsZ-GDP were strongly dependent on ionic strength, being severely reduced at 500 mM KCl compared with 100 mM KCl. Our results support a mechanism in which MinC interacts with FtsZ-GDP, resulting in smaller protofilaments of defined size and having the same effect on both preassembled and growing FtsZ protofilaments.
authors.affiliation: Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain.
authors.forename: Víctor M
authors.initials: VM
authors.lastname: Hernández-Rocamora
authors.forename: Concepción
authors.initials: C
authors.lastname: García-Montañés
authors.forename: Belén
authors.initials: B
authors.lastname: Reija
authors.forename: Begoña
authors.initials: B
authors.lastname: Monterroso
authors.forename: William
authors.initials: W
authors.lastname: Margolin
authors.forename: Carlos
authors.initials: C
authors.lastname: Alfonso
authors.forename: Silvia
authors.initials: S
authors.lastname: Zorrilla
authors.forename: Germán
authors.initials: G
authors.lastname: Rivas
mesh_terms: D004926:Escherichia coli / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009994:Osmolar Concentration; D011485:Protein Binding; D055503:Protein Multimerization
chemical_list: D029968:Escherichia coli Proteins; D008565:Membrane Proteins; C462942:MinC protein, E coli; D046912:Multiprotein Complexes; D006160:Guanosine Triphosphate
keywords: Biophysics; Cell Division; Escherichia coli; FtsZ Assembly; Min System; Protein Complexes; Protein-Protein Interactions