Abstract
The anaphase-promoting complex/cyclosome (APC/C) is a ~1.5-MDa multiprotein E3 ligase enzyme that regulates cell division by promoting timely ubiquitin-mediated proteolysis of key cell-cycle regulatory proteins. Inhibition of human APC/C(CDH1) during interphase by early mitotic inhibitor 1 (EMI1) is essential for accurate coordination of DNA synthesis and mitosis. Here, we report a hybrid structural approach involving NMR, electron microscopy and enzymology, which reveal that EMI1's 143-residue C-terminal domain inhibits multiple APC/C(CDH1) functions. The intrinsically disordered D-box, linker and tail elements, together with a structured zinc-binding domain, bind distinct regions of APC/C(CDH1) to synergistically both block the substrate-binding site and inhibit ubiquitin-chain elongation. The functional importance of intrinsic structural disorder is explained by enabling a small inhibitory domain to bind multiple sites to shut down various functions of a 'molecular machine' nearly 100 times its size.
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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Anaphase-Promoting Complex-Cyclosome
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Antigens, CD
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Cadherins / chemistry*
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Cell Cycle Proteins / chemistry*
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Cell Cycle Proteins / metabolism
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Cell Cycle Proteins / pharmacology
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Cell Cycle Proteins / ultrastructure
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F-Box Proteins / chemistry*
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F-Box Proteins / metabolism
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F-Box Proteins / pharmacology
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F-Box Proteins / ultrastructure
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Humans
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Microscopy, Electron
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Models, Molecular
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Molecular Sequence Data
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Protein Binding
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Protein Conformation
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Protein Folding
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Protein Processing, Post-Translational
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Protein Structure, Tertiary
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Sequence Alignment
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Sequence Homology, Amino Acid
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Structure-Activity Relationship
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Substrate Specificity
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Ubiquitin-Protein Ligase Complexes / antagonists & inhibitors
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Ubiquitin-Protein Ligase Complexes / chemistry*
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Ubiquitin-Protein Ligase Complexes / metabolism
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Ubiquitin-Protein Ligase Complexes / ultrastructure
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Ubiquitin-Protein Ligases / antagonists & inhibitors
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Ubiquitinated Proteins / metabolism
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Ubiquitination
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Ultracentrifugation
Substances
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Antigens, CD
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CDH1 protein, human
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Cadherins
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Cell Cycle Proteins
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F-Box Proteins
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FBXO5 protein, human
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Ubiquitinated Proteins
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Ubiquitin-Protein Ligase Complexes
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Anaphase-Promoting Complex-Cyclosome
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Ubiquitin-Protein Ligases