title: Fission yeast MOZART1/Mzt1 is an essential γ-tubulin complex component required for complex recruitment to the microtubule organizing center, but not its assembly.
abstract: γ-Tubulin plays a universal role in microtubule nucleation from microtubule organizing centers (MTOCs) such as the animal centrosome and fungal spindle pole body (SPB). γ-Tubulin functions as a multiprotein complex called the γ-tubulin complex (γ-TuC), consisting of GCP1-6 (GCP1 is γ-tubulin). In fungi and flies, it has been shown that GCP1-3 are core components, as they are indispensable for γ-TuC complex assembly and cell division, whereas the other three GCPs are not. Recently a novel conserved component, MOZART1, was identified in humans and plants, but its precise functions remain to be determined. In this paper, we characterize the fission yeast homologue Mzt1, showing that it is essential for cell viability. Mzt1 is present in approximately equal stoichiometry with Alp4/GCP2 and localizes to all the MTOCs, including the SPB and interphase and equatorial MTOCs. Temperature-sensitive mzt1 mutants display varying degrees of compromised microtubule organization, exhibiting multiple defects during both interphase and mitosis. Mzt1 is required for γ-TuC recruitment, but not sufficient to localize to the SPB, which depends on γ-TuC integrity. Intriguingly, the core γ-TuC assembles in the absence of Mzt1. Mzt1 therefore plays a unique role within the γ-TuC components in attachment of this complex to the major MTOC site.
authors.affiliation: Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London WC2A 3LY, United Kingdom Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530, Japan.
authors.forename: Hirohisa
authors.initials: H
authors.lastname: Masuda
authors.forename: Risa
authors.initials: R
authors.lastname: Mori
authors.forename: Masashi
authors.initials: M
authors.lastname: Yukawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Toda
mesh_terms: D000595:Amino Acid Sequence; D000705:Anaphase; D020090:Chromosome Segregation; D005800:Genes, Fungal; D007399:Interphase; D050296:Microbial Viability; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D022101:Microtubule-Organizing Center / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D021381:Protein Transport; D012568:Schizosaccharomyces / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D064047:Spindle Poles / Q000378:metabolism; D013696:Temperature; D014404:Tubulin / Q000378:metabolism*
chemical_list: D008869:Microtubule-Associated Proteins; D046912:Multiprotein Complexes; C000589192:Mzt1 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; D014404:Tubulin