Abstract
The spindle pole body (SPB) is the sole site of microtubule nucleation in Saccharomyces cerevisiae; yet, details of its assembly are poorly understood. Integral membrane proteins including Mps2 anchor the soluble core SPB in the nuclear envelope. Adjacent to the core SPB is a membrane-associated SPB substructure known as the half-bridge, where SPB duplication and microtubule nucleation during G1 occurs. We found that the half-bridge component Mps3 is the budding yeast member of the SUN protein family (Sad1-UNC-84 homology) and provide evidence that it interacts with the Mps2 C terminus to tether the half-bridge to the core SPB. Mutants in the Mps3 SUN domain or Mps2 C terminus have SPB duplication and karyogamy defects that are consistent with the aberrant half-bridge structures we observe cytologically. The interaction between the Mps3 SUN domain and Mps2 C terminus is the first biochemical link known to connect the half-bridge with the core SPB. Association with Mps3 also defines a novel function for Mps2 during SPB duplication.
Publication types
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Comparative Study
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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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Amino Acid Sequence
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Cell Cycle / genetics
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Centrosome / metabolism
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Checkpoint Kinase 2
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Chromosome Segregation
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Membrane Proteins / chemistry
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Membrane Proteins / genetics*
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Membrane Proteins / metabolism*
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Molecular Sequence Data
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Mutation
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Nuclear Envelope / metabolism*
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Nuclear Proteins / chemistry
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism*
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Protein Binding
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Protein Serine-Threonine Kinases / genetics
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Protein Serine-Threonine Kinases / metabolism*
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Protein Structure, Tertiary
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Saccharomyces cerevisiae / genetics
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae / physiology*
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Saccharomyces cerevisiae Proteins / chemistry
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Saccharomyces cerevisiae Proteins / genetics*
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Saccharomyces cerevisiae Proteins / metabolism*
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Sequence Alignment
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Sequence Homology, Amino Acid
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Spindle Apparatus / metabolism*
Substances
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Cell Cycle Proteins
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MPS2 protein, S cerevisiae
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Membrane Proteins
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Mps3 protein, S cerevisiae
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Nuclear Proteins
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Saccharomyces cerevisiae Proteins
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Checkpoint Kinase 2
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Protein Serine-Threonine Kinases
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RAD53 protein, S cerevisiae