Abstract
The formation of functional kinetochores requires the accurate assembly of a large number of protein complexes. The Hsp90-Sgt1 chaperone complex is important for this process; however, its targets are not conserved and its exact contribution to kinetochore assembly is unclear. Here, we show that human Hsp90-Sgt1 interacts with the Mis12 complex, a so-called keystone complex required to assemble a large fraction of the kinetochore. Inhibition of Hsp90 or Sgt1 destabilizes the Mis12 complex and delays proper chromosome alignment due to inefficient formation of microtubule-binding sites. Interestingly, coinhibition of Sgt1 and the SCF subunit, Skp1, increases Mis12 complexes at kinetochores and restores timely chromosome alignment but forms less-robust microtubule-binding sites. We propose that a balance of Mis12 complex assembly and turnover is required for the efficient and accurate assembly of kinetochore-microtubule binding sites. These findings support a novel role for Hsp90-Sgt1 chaperones in ensuring the fidelity of multiprotein complex assembly.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Binding Sites
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Chromosomal Proteins, Non-Histone / genetics
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Chromosomal Proteins, Non-Histone / metabolism
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HSP90 Heat-Shock Proteins / chemistry
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HSP90 Heat-Shock Proteins / genetics
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HSP90 Heat-Shock Proteins / metabolism*
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HeLa Cells
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Humans
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Kinetochores / metabolism*
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Kinetochores / ultrastructure
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Microtubule-Associated Proteins / genetics
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Microtubule-Associated Proteins / metabolism*
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Microtubules / metabolism*
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Multiprotein Complexes / metabolism*
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Protein Binding
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RNA, Small Interfering / genetics
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RNA, Small Interfering / metabolism
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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SKP Cullin F-Box Protein Ligases / genetics
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SKP Cullin F-Box Protein Ligases / metabolism*
Substances
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Cell Cycle Proteins
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Chromosomal Proteins, Non-Histone
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DSN1 protein, human
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HSP90 Heat-Shock Proteins
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MIS12 protein, human
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Microtubule-Associated Proteins
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Multiprotein Complexes
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RNA, Small Interfering
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Recombinant Fusion Proteins
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SUGT1 protein, human
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SKP Cullin F-Box Protein Ligases