Abstract
The status of spindle checkpoint signaling depends on the balance of two opposing dynamic processes that regulate the highly unusual two-state behavior of Mad2. In mitosis, a Mad1-Mad2 core complex recruits cytosolic Mad2 to kinetochores through Mad2 dimerization and converts Mad2 to a conformer amenable to Cdc20 binding, thereby facilitating checkpoint activation. p31(comet) inactivates the checkpoint through binding to Mad1- or Cdc20-bound Mad2, thereby preventing Mad2 activation and promoting the dissociation of the Mad2-Cdc20 complex. Here, we report the crystal structure of the Mad2-p31(comet) complex. The C-terminal region of Mad2 that undergoes rearrangement in different Mad2 conformers is a major structural determinant for p31(comet) binding, explaining the specificity of p31(comet) toward Mad1- or Cdc20-bound Mad2. p31(comet) adopts a fold strikingly similar to that of Mad2 and binds at the dimerization interface of Mad2. Thus, p31(comet) exploits the two-state behavior of Mad2 to block its activation by acting as an "anti-Mad2."
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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Adaptor Proteins, Signal Transducing / chemistry*
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Adaptor Proteins, Signal Transducing / genetics
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Adaptor Proteins, Signal Transducing / metabolism*
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Allosteric Regulation
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Amino Acid Sequence
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Animals
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Calcium-Binding Proteins / chemistry*
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Calcium-Binding Proteins / genetics
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Calcium-Binding Proteins / metabolism*
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Cell Cycle / physiology
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Cell Cycle Proteins / chemistry*
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Cell Cycle Proteins / genetics
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Cell Cycle Proteins / metabolism*
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Cell Line
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Crystallography, X-Ray
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Humans
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Mad2 Proteins
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Models, Molecular
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Molecular Mimicry*
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Molecular Sequence Data
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Multiprotein Complexes / chemistry
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Multiprotein Complexes / metabolism
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Nocodazole / 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 Structure, Secondary
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Protein Structure, Tertiary*
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Repressor Proteins / chemistry*
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Repressor Proteins / genetics
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Repressor Proteins / metabolism*
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Sequence Alignment
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Tubulin Modulators / metabolism
Substances
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Adaptor Proteins, Signal Transducing
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Calcium-Binding Proteins
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Cell Cycle Proteins
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MAD2L1 protein, human
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MAD2L1BP protein, human
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Mad2 Proteins
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Multiprotein Complexes
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Nuclear Proteins
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Repressor Proteins
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Tubulin Modulators
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Nocodazole