Frye, Jeremiah J.Jeremiah J.FryeBrown, Nicholas G.Nicholas G.BrownPetzold, GeorgGeorgPetzoldWatson, Edmond R.Edmond R.WatsonGrace, Christy R. R.Christy R. R.GraceNourse, AmandaAmandaNourseJarvis, Marc A.Marc A.JarvisKriwacki, Richard W.Richard W.KriwackiPeters, Jan-MichaelJan-MichaelPetersStark, HolgerHolgerStarkSchulman, Brenda A.Brenda A.Schulman2018-11-072018-11-072013https://resolver.sub.uni-goettingen.de/purl?gro-2/29531The anaphase-promoting complex/cyclosome (APC/C) is a similar to 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.journal_article10.1038/nsmb.259323708605000321253300011