Cut1/separase C-terminus affects spindle pole body positioning in interphase of fission yeast: pointed nuclear formation.
BACKGROUND
The separase-securin complex is required for anaphase. Separase activated by securin destruction cleaves the cohesin subunit Scc1/Rad21 enriched in kinetochores. Fission yeast Cut1/separase resides in interphase cytoplasm and mobilizes to the spindle and the spindle pole bodies (SPBs) in mitosis, while Cut2/securin remains in the nucleus from interphase to metaphase, and temporarily locates at the short spindle.


RESULTS
We here report a novel SPB-led dynamic nuclear movement in fission yeast, when the Cut1 C-terminal fragment is over-expressed. The tip of the pointed nucleus contained both SPB and centromeric DNA, and rapidly moved along the bundled cytoplasmic microtubules. The same pointed nucleus was produced when the human separase C-fragment was over-expressed. The pointed nuclear formation did not require the protease site of separase, but required the conserved C-terminus and a microtubule- and kinetochore-binding protein Mtc1/Alp14, a homologue of frog XMAP215 and budding yeast Stu2. The movement-inducing C-fragment should be cytoplasmic, as the pointed nucleus was abolished when the fragment contained the NLS (nuclear localization signal).


CONCLUSIONS
Overproduced separase C-fragment abolishes correct SPB-positioning in interphase. Resulting pointed nuclear formation (alternatively called 'pigtail movement') requires cytoplasmic microtubules and Mtc1/Alp14.
Nakamura
Takahiro
T
Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 Japan.
Nagao
Koji
K
Nakaseko
Yukinobu
Y
Yanagida
Mitsuhiro
M
D020134:Catalytic Domain / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D017124:Conserved Sequence; D010450:Endopeptidases; D007399:Interphase / Q000502:physiology; D018386:Kinetochores / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism; D009154:Mutation; D009685:Nuclear Envelope / Q000378:metabolism; D012568:Schizosaccharomyces / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins; D064247:Separase; D008941:Spindle Apparatus / Q000378:metabolism*
D018797:Cell Cycle Proteins; C103135:Cut1 protein, S pombe; D008869:Microtubule-Associated Proteins; D029702:Schizosaccharomyces pombe Proteins; C432090:alp14 protein, S pombe; D010450:Endopeptidases; C577987:ESPL1 protein, human; D064247:Separase