Modes of spindle pole body inheritance and segregation of the Bfa1p-Bub2p checkpoint protein complex.
Yeast spindle pole bodies (SPBs) duplicate once per cell cycle by a conservative mechanism resulting in a pre-existing 'old' and a newly formed SPB. The two SPBs of yeast cells are functionally distinct. It is only the SPB that migrates into the daughter cell, the bud, which carries the Bfa1p-Bub2p GTPase-activating protein (GAP) complex, a component of the spindle positioning checkpoint. We investigated whether the functional difference of the two SPBs correlates with the time of their assembly. We describe that in unperturbed cells the 'old' SPB always migrates into the bud. However, Bfa1p localization is not determined by SPB inheritance. It is the differential interaction of cytoplasmic microtubules with the mother and bud cortex that directs the Bfa1p-Bub2p GAP to the bud-ward-localized SPB. In response to defects of cytoplasmic microtubules to interact with the cell cortex, the Bfa1p-Bub2p complex binds to both SPBs. This may provide a mechanism to delay cell cycle progression when cytoplasmic microtubules fail to orient the spindle. Thus, SPBs are able to sense cytoplasmic microtubule properties and regulate the Bfa1p-Bub2p GAP accordingly.
Pereira
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G
The Beatson Institute for Cancer Research, CRC Beatson Laboratories, Glasgow G61 1BD, UK.
Tanaka
T U
TU
Nasmyth
K
K
Schiebel
E
E
D000970:Antineoplastic Agents / Q000494:pharmacology; D018797:Cell Cycle Proteins; D002455:Cell Division; D003593:Cytoplasm / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D005656:Fungal Proteins / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000378:metabolism; D005838:Genotype; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism; D008954:Models, Biological; D015739:Nocodazole / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D029701:Saccharomyces cerevisiae Proteins; D004718:Saccharomycetales / Q000502:physiology; D013997:Time Factors; D000097573:Red Fluorescent Protein
D000970:Antineoplastic Agents; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D005656:Fungal Proteins; D020690:GTPase-Activating Proteins; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D015739:Nocodazole; D010750:Phosphoproteins; D029701:Saccharomyces cerevisiae Proteins; D000097573:Red Fluorescent Protein; C119117:BFA1 protein, S cerevisiae; C070351:BUB2 protein, S cerevisiae; C432692:SPC42 protein, S cerevisiae