title: Intrakinetochore localization and essential functional domains of Drosophila Spc105.
abstract: The kinetochore is assembled during mitotic and meiotic divisions within the centromeric region of chromosomes. It is composed of more than eighty different proteins. Spc105 (also designated as Spc7, KNL-1 or Blinkin in different eukaryotes) is a comparatively large kinetochore protein, which can bind to the Mis12/MIND and Ndc80 complexes and to the spindle assembly checkpoint components Bub1 and BubR1. Our genetic characterization of Drosophila Spc105 shows that a truncated version lacking the rapidly evolving, repetitive central third still provides all essential functions. Moreover, in comparison with Cenp-C that has previously been observed to extend from the inner to the outer kinetochore region, full-length Spc105 is positioned further out and is not similarly extended along the spindle axis. Thus, our results indicate that Spc105 forms neither an extended link connecting inner Cenp-A chromatin with outer kinetochore regions nor a scaffold constraining kinetochore subcomplexes and spindle assembly checkpoint components together into a geometrically rigid supercomplex. Spc105 seems to provide a platform within the outer kinetochore allowing independent assembly of various kinetochore components.
authors: Institute of Zoology, University of Zurich, Zurich, Switzerland.
authors: Ralf B
authors: RB
authors: Schittenhelm
authors: Romanas
authors: R
authors: Chaleckis
authors: Christian F
authors: CF
authors: Lehner
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001324:Autoantigens / Q000032:analysis; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone / Q000032:analysis / Q000235:genetics; D029721:Drosophila Proteins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D018386:Kinetochores / Q000737:chemistry* / Q000378:metabolism*; D008938:Mitosis; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D017434:Protein Structure, Tertiary; D020449:Repetitive Sequences, Amino Acid; D008941:Spindle Apparatus / Q000235:genetics / Q000378:metabolism
chemical_list: D001324:Autoantigens; D000076247:Centromere Protein A; D002868:Chromosomal Proteins, Non-Histone; D029721:Drosophila Proteins; C541602:Spc105R protein, Drosophila; C060905:centromere protein C