Direct binding of NuMA to tubulin is mediated by a novel sequence motif in the tail domain that bundles and stabilizes microtubules.
In mitosis, NuMA localises to spindle poles where it contributes to the formation and maintenance of focussed microtubule arrays. Previous work has shown that NuMA is transported to the poles by dynein and dynactin. So far, it is unclear how NuMA accumulates at the spindle poles following transport and how it remains associated throughout mitosis. We show here that NuMA can bind to microtubules independently of dynein/dynactin. We characterise a 100-residue domain located within the C-terminal tail of NuMA that mediates a direct interaction with tubulin in vitro and that is necessary for NuMA association with tubulin in vivo. Moreover, this domain induces bundling and stabilisation of microtubules when expressed in cultured cells and leads to formation of abnormal mitotic spindles with increased microtubule asters or multiple poles. Our results suggest that NuMA organises the poles by stable crosslinking of the microtubule fibers.
Haren
Laurence
L
Wellcome Trust Centre for Cell Biology, Institute of Cell and Molecular Biology, University of Edinburgh, King's Buildings, Edinburgh, EH9 3JR, UK.
Merdes
Andreas
A
D020816:Amino Acid Motifs / Q000502:physiology; D000595:Amino Acid Sequence / Q000502:physiology; D000818:Animals; D034961:Antigens, Nuclear; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000502:physiology*; D000072159:Dynactin Complex; D004398:Dyneins / Q000378:metabolism; D005057:Eukaryotic Cells / Q000166:cytology / Q000378:metabolism*; D005260:Female; D006367:HeLa Cells; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism*; D008954:Models, Biological; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins / Q000378:metabolism*; D009865:Oocytes; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D008941:Spindle Apparatus / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism*; D029867:Xenopus Proteins; D014982:Xenopus laevis
D034961:Antigens, Nuclear; D018797:Cell Cycle Proteins; D000072159:Dynactin Complex; D008869:Microtubule-Associated Proteins; C489079:NUMA1 protein, Xenopus; C050045:NUMA1 protein, human; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins; D010446:Peptide Fragments; D014404:Tubulin; D029867:Xenopus Proteins; D004398:Dyneins