title: Non-sporulating ftsZ mutants in Streptomyces coelicolor reveal amino acid residues critical for FtsZ polymerization dynamics.
abstract: During sporulation of Streptomyces coelicolor, the cytokinetic protein FtsZ is assembled into dozens of regularly spaced Z rings, which orchestrate the division of aerial hyphae into spores. We have previously found that a missense allele of ftsZ, ftsZ17(Spo), primarily affects sporulation septation rather than formation of cross-walls in vegetative mycelium. To clarify what aspect of FtsZ function is compromised in such non-sporulating mutants, we here use a genetic strategy to identify new ftsZ(Spo) alleles and describe how some of the mutations affect the biochemical properties of FtsZ. We have established a system for purification of recombinant untagged S. coelicolor FtsZ, and shown that it assembles dynamically into single protofilaments, displays a critical concentration indicative of cooperative assembly and has a rate of GTP hydrolysis that is substantially higher than that of the closely related Mycobacterium tuberculosis FtsZ. Of the nine isolated ftsZ(Spo) mutations, four affect the interface between the two main subdomains of FtsZ that is implicated in the assembly-induced conformational changes thought to mediate the GTP/GDP-driven cooperative assembly of FtsZ. We find that all these four mutations affect the polymerization behaviour of FtsZ in vitro. In addition, at least one ftsZ(Spo) mutation at the longitudinal contact surface between subunits in protofilaments strongly affects formation of polymers in vitro. We conclude that the assembly of Z rings during sporulation of S. coelicolor is highly sensitive to disturbances of FtsZ polymerization and therefore constitutes an excellent system for analysis of the elusive properties of FtsZ that mediate its characteristic polymerization dynamics.
authors.affiliation: Department of Biology, Lund University, 223 62 Lund, Sweden.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Wasserstrom
authors.affiliation: Department of Cell and Molecular Biology, Uppsala University, 751 24 Uppsala, Sweden.
authors.forename: Nina
authors.initials: N
authors.lastname: Grantcharova
authors.affiliation: Department of Cell and Molecular Biology, Uppsala University, 751 24 Uppsala, Sweden.
authors.forename: Wimal
authors.initials: W
authors.lastname: Ubhayasekera
authors.affiliation: Department of Cell and Molecular Biology, Uppsala University, 751 24 Uppsala, Sweden.|Department of Biology, Lund University, 223 62 Lund, Sweden.
authors.forename: Nora
authors.initials: N
authors.lastname: Ausmees
authors.affiliation: Department of Molecular Biology, 901 87 Umeå University, Sweden.
authors.forename: Linda
authors.initials: L
authors.lastname: Sandblad
authors.affiliation: Department of Cell and Molecular Biology, Uppsala University, 751 24 Uppsala, Sweden.|Department of Biology, Lund University, 223 62 Lund, Sweden.
authors.forename: Klas
authors.initials: K
authors.lastname: Flärdh
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D058105:Polymerization; D013171:Spores, Bacterial / Q000737:chemistry / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D048372:Streptomyces coelicolor / Q000737:chemistry / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D003598:Cytoskeletal Proteins; C071525:FtsZ protein, Bacteria