Physical limits on kinesin-5-mediated chromosome congression in the smallest mitotic spindles
A characteristic feature of mitotic spindles is the congression of chromosomes near the spindle equator, a process mediated by dynamic kinetochore microtubules. A major challenge is to understand how precise, submicrometer-scale control of kinetochore microtubule dynamics is achieved in the smalles...
| Main Authors: | , , , , , , , |
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| Format: | Article |
| Language: | en_US |
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American Society for Cell Biology
2015
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| Online Access: | http://hdl.handle.net/1721.1/100563 https://orcid.org/0000-0003-1224-8153 |
| _version_ | 1811095444463288320 |
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| author | McCoy, K. M. Tubman, E. S. Tank, D. Clancy, S. A. O'Toole, E. T. Berman, J. Odde, D. J. Claas, Allison Mary |
| author2 | Massachusetts Institute of Technology. Department of Biological Engineering |
| author_facet | Massachusetts Institute of Technology. Department of Biological Engineering McCoy, K. M. Tubman, E. S. Tank, D. Clancy, S. A. O'Toole, E. T. Berman, J. Odde, D. J. Claas, Allison Mary |
| author_sort | McCoy, K. M. |
| collection | MIT |
| description | A characteristic feature of mitotic spindles is the congression of chromosomes near the spindle equator, a process mediated by dynamic kinetochore microtubules. A major challenge is to understand how precise, submicrometer-scale control of kinetochore microtubule dynamics is achieved in the smallest mitotic spindles, where the noisiness of microtubule assembly/disassembly will potentially act to overwhelm the spatial information that controls microtubule plus end–tip positioning to mediate congression. To better understand this fundamental limit, we conducted an integrated live fluorescence, electron microscopy, and modeling analysis of the polymorphic fungal pathogen Candida albicans, which contains one of the smallest known mitotic spindles (<1 μm). Previously, ScCin8p (kinesin-5 in Saccharomyces cerevisiae) was shown to mediate chromosome congression by promoting catastrophe of long kinetochore microtubules (kMTs). Using C. albicans yeast and hyphal kinesin-5 (Kip1p) heterozygotes (KIP1/kip1∆), we found that mutant spindles have longer kMTs than wild-type spindles, consistent with a less-organized spindle. By contrast, kinesin-8 heterozygous mutant (KIP3/kip3∆) spindles exhibited the same spindle organization as wild type. Of interest, spindle organization in the yeast and hyphal states was indistinguishable, even though yeast and hyphal cell lengths differ by two- to fivefold, demonstrating that spindle length regulation and chromosome congression are intrinsic to the spindle and largely independent of cell size. Together these results are consistent with a kinesin-5–mediated, length-dependent depolymerase activity that organizes chromosomes at the spindle equator in C. albicans to overcome fundamental noisiness in microtubule self-assembly. More generally, we define a dimensionless number that sets a fundamental physical limit for maintaining congression in small spindles in the face of assembly noise and find that C. albicans operates very close to this limit, which may explain why it has the smallest known mitotic spindle that still manifests the classic congression architecture. |
| first_indexed | 2024-09-23T16:16:52Z |
| format | Article |
| id | mit-1721.1/100563 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T16:16:52Z |
| publishDate | 2015 |
| publisher | American Society for Cell Biology |
| record_format | dspace |
| spelling | mit-1721.1/1005632022-10-02T07:33:32Z Physical limits on kinesin-5-mediated chromosome congression in the smallest mitotic spindles McCoy, K. M. Tubman, E. S. Tank, D. Clancy, S. A. O'Toole, E. T. Berman, J. Odde, D. J. Claas, Allison Mary Massachusetts Institute of Technology. Department of Biological Engineering Claas, Allison Mary A characteristic feature of mitotic spindles is the congression of chromosomes near the spindle equator, a process mediated by dynamic kinetochore microtubules. A major challenge is to understand how precise, submicrometer-scale control of kinetochore microtubule dynamics is achieved in the smallest mitotic spindles, where the noisiness of microtubule assembly/disassembly will potentially act to overwhelm the spatial information that controls microtubule plus end–tip positioning to mediate congression. To better understand this fundamental limit, we conducted an integrated live fluorescence, electron microscopy, and modeling analysis of the polymorphic fungal pathogen Candida albicans, which contains one of the smallest known mitotic spindles (<1 μm). Previously, ScCin8p (kinesin-5 in Saccharomyces cerevisiae) was shown to mediate chromosome congression by promoting catastrophe of long kinetochore microtubules (kMTs). Using C. albicans yeast and hyphal kinesin-5 (Kip1p) heterozygotes (KIP1/kip1∆), we found that mutant spindles have longer kMTs than wild-type spindles, consistent with a less-organized spindle. By contrast, kinesin-8 heterozygous mutant (KIP3/kip3∆) spindles exhibited the same spindle organization as wild type. Of interest, spindle organization in the yeast and hyphal states was indistinguishable, even though yeast and hyphal cell lengths differ by two- to fivefold, demonstrating that spindle length regulation and chromosome congression are intrinsic to the spindle and largely independent of cell size. Together these results are consistent with a kinesin-5–mediated, length-dependent depolymerase activity that organizes chromosomes at the spindle equator in C. albicans to overcome fundamental noisiness in microtubule self-assembly. More generally, we define a dimensionless number that sets a fundamental physical limit for maintaining congression in small spindles in the face of assembly noise and find that C. albicans operates very close to this limit, which may explain why it has the smallest known mitotic spindle that still manifests the classic congression architecture. 2015-12-30T19:25:33Z 2015-12-30T19:25:33Z 2015-09 2015-08 Article http://purl.org/eprint/type/JournalArticle 1059-1524 1939-4586 http://hdl.handle.net/1721.1/100563 McCoy, K. M., E. S. Tubman, A. Claas, D. Tank, S. A. Clancy, E. T. O’Toole, J. Berman, and D. J. Odde. “Physical Limits on Kinesin-5-Mediated Chromosome Congression in the Smallest Mitotic Spindles.” Molecular Biology of the Cell 26, no. 22 (September 9, 2015): 3999–4014. https://orcid.org/0000-0003-1224-8153 en_US http://dx.doi.org/10.1091/mbc.E14-10-1454 Molecular Biology of the Cell Creative Commons Attribution http://creativecommons.org/licenses/by-nc-sa/3.0/ application/pdf American Society for Cell Biology American Society for Cell Biology |
| spellingShingle | McCoy, K. M. Tubman, E. S. Tank, D. Clancy, S. A. O'Toole, E. T. Berman, J. Odde, D. J. Claas, Allison Mary Physical limits on kinesin-5-mediated chromosome congression in the smallest mitotic spindles |
| title | Physical limits on kinesin-5-mediated chromosome congression in the smallest mitotic spindles |
| title_full | Physical limits on kinesin-5-mediated chromosome congression in the smallest mitotic spindles |
| title_fullStr | Physical limits on kinesin-5-mediated chromosome congression in the smallest mitotic spindles |
| title_full_unstemmed | Physical limits on kinesin-5-mediated chromosome congression in the smallest mitotic spindles |
| title_short | Physical limits on kinesin-5-mediated chromosome congression in the smallest mitotic spindles |
| title_sort | physical limits on kinesin 5 mediated chromosome congression in the smallest mitotic spindles |
| url | http://hdl.handle.net/1721.1/100563 https://orcid.org/0000-0003-1224-8153 |
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