Mal3, the fission yeast EB1 homologue, cooperates with Bub1 spindle checkpoint to prevent monopolar attachment.
Bipolar microtubule attachment is central to genome stability. Here, we investigate the mitotic role of the fission yeast EB1 homologue Mal3. Mal3 shows dynamic inward movement along the spindle, initial emergence at the spindle pole body (SPB) and translocation towards the equatorial plane, followed by sudden disappearance. Deletion of Mal3 results in early mitotic delay, which is dependent on the Bub1, but not the Mad2, spindle checkpoint. Consistently, Bub1, but not Mad2, shows prolonged kinetochore localization. Double mutants between mal3 and a subset of checkpoint mutants, including bub1, bub3, mad3 and mph1, but not mad1 or mad2, show massive chromosome mis-segregation defects. In mal3bub1 mutants, both sister centromeres tend to remain in close proximity to one of the separating SPBs. Further analysis indicates that mis-segregated centromeres are exclusively associated with the mother SPB. Mal3, therefore, has a role in preventing monopolar attachment in cooperation with the Bub1/Bub3/Mad3/Mph1-dependent checkpoint.
Asakawa
Kazuhide
K
Laboratory of Cell Regulation, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, 44 Lincoln's Inn Fields, London WC2A 3PX, UK.
Toya
Mika
M
Sato
Masamitsu
M
Kanai
Muneyoshi
M
Kume
Kazunori
K
Goshima
Tetsuya
T
Garcia
Miguel Angel
MA
Hirata
Dai
D
Toda
Takashi
T
D018797:Cell Cycle Proteins; D002503:Centromere / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005819:Genetic Markers; D018386:Kinetochores / Q000378:metabolism; D018715:Microscopy, Video; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000235:genetics* / Q000254:growth & development; D029702:Schizosaccharomyces pombe Proteins / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D008941:Spindle Apparatus / Q000502:physiology*
D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D005819:Genetic Markers; C108851:Mal3 protein, S pombe; D008869:Microtubule-Associated Proteins; D029702:Schizosaccharomyces pombe Proteins; C495594:Bub1 protein, S pombe; D017346:Protein Serine-Threonine Kinases