title: Electron microscopy structure of human APC/C(CDH1)-EMI1 reveals multimodal mechanism of E3 ligase shutdown.
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.
authors.affiliation: 1Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors.forename: Jeremiah J
authors.initials: JJ
authors.lastname: Frye
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Brown
authors.forename: Georg
authors.initials: G
authors.lastname: Petzold
authors.forename: Edmond R
authors.initials: ER
authors.lastname: Watson
authors.forename: Christy R R
authors.initials: CR
authors.lastname: Grace
authors.forename: Amanda
authors.initials: A
authors.lastname: Nourse
authors.forename: Marc A
authors.initials: MA
authors.lastname: Jarvis
authors.forename: Richard W
authors.initials: RW
authors.lastname: Kriwacki
authors.forename: Jan-Michael
authors.initials: JM
authors.lastname: Peters
authors.forename: Holger
authors.initials: H
authors.lastname: Stark
authors.forename: Brenda A
authors.initials: BA
authors.lastname: Schulman
mesh_terms: D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D015703:Antigens, CD; D015820:Cadherins / Q000737:chemistry*; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology / Q000648:ultrastructure; D044783:F-Box Proteins / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology / Q000648:ultrastructure; D006801:Humans; D008854:Microscopy, Electron; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D043743:Ubiquitin-Protein Ligase Complexes / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D044767:Ubiquitin-Protein Ligases / Q000037:antagonists & inhibitors; D057149:Ubiquitinated Proteins / Q000378:metabolism; D054875:Ubiquitination; D014461:Ultracentrifugation
chemical_list: D015703:Antigens, CD; C513384:CDH1 protein, human; D015820:Cadherins; D018797:Cell Cycle Proteins; D044783:F-Box Proteins; C498960:FBXO5 protein, human; D057149:Ubiquitinated Proteins; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D044767:Ubiquitin-Protein Ligases