title: Cryo-EM of Mitotic Checkpoint Complex-Bound APC/C Reveals Reciprocal and Conformational Regulation of Ubiquitin Ligation.
abstract: The mitotic checkpoint complex (MCC) coordinates proper chromosome biorientation on the spindle with ubiquitination activities of CDC20-activated anaphase-promoting complex/cyclosome (APC/C(CDC20)). APC/C(CDC20) and two E2s, UBE2C and UBE2S, catalyze ubiquitination through distinct architectures for linking ubiquitin (UB) to substrates and elongating polyUB chains, respectively. MCC, which contains a second molecule of CDC20, blocks APC/C(CDC20)-UBE2C-dependent ubiquitination of Securin and Cyclins, while differentially determining or inhibiting CDC20 ubiquitination to regulate spindle surveillance, checkpoint activation, and checkpoint termination. Here electron microscopy reveals conformational variation of APC/C(CDC20)-MCC underlying this multifaceted regulation. MCC binds APC/C-bound CDC20 to inhibit substrate access. However, rotation about the CDC20-MCC assembly and conformational variability of APC/C modulate UBE2C-catalyzed ubiquitination of MCC's CDC20 molecule. Access of UBE2C is limiting for subsequent polyubiquitination by UBE2S. We propose that conformational dynamics of APC/C(CDC20)-MCC modulate E2 activation and determine distinctive ubiquitination activities as part of a response mechanism ensuring accurate sister chromatid segregation.
authors: Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
authors: Masaya
authors: M
authors: Yamaguchi
authors: Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
authors: Ryan
authors: R
authors: VanderLinden
authors: Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), 1030 Vienna, Austria.
authors: Florian
authors: F
authors: Weissmann
authors: Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), 1030 Vienna, Austria.
authors: Renping
authors: R
authors: Qiao
authors: Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
authors: Prakash
authors: P
authors: Dube
authors: Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
authors: Nicholas G
authors: NG
authors: Brown
authors: Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany.
authors: David
authors: D
authors: Haselbach
authors: Donnelly Centre for Cellular and Biomolecular Research and Banting and Best Department of Medical Research, University of Toronto, Toronto, ON M5S3E1, Canada.
authors: Wei
authors: W
authors: Zhang
authors: Donnelly Centre for Cellular and Biomolecular Research and Banting and Best Department of Medical Research, University of Toronto, Toronto, ON M5S3E1, Canada.
authors: Sachdev S
authors: SS
authors: Sidhu
authors: Research Institute of Molecular Pathology (IMP), Vienna Biocenter (VBC), 1030 Vienna, Austria. Electronic address: jan-michael.peters@imp.ac.at.
authors: Jan-Michael
authors: JM
authors: Peters
authors: Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany. Electronic address: hstark1@gwdg.de.
authors: Holger
authors: H
authors: Stark
authors: Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA; Howard Hughes Medical Institute, St. Jude Children's Research Hospital, Memphis, TN 38105, USA. Electronic address: brenda.schulman@stjude.org.
authors: Brenda A
authors: BA
authors: Schulman
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome / Q000378:metabolism* / Q000648:ultrastructure*; D001665:Binding Sites; D064199:Cdc20 Proteins / Q000378:metabolism / Q000648:ultrastructure; D020090:Chromosome Segregation; D020285:Cryoelectron Microscopy; D006801:Humans; D059566:M Phase Cell Cycle Checkpoints; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D008941:Spindle Apparatus / Q000378:metabolism* / Q000648:ultrastructure*; D013329:Structure-Activity Relationship; D025801:Ubiquitin / Q000378:metabolism*; D044764:Ubiquitin-Activating Enzymes / Q000378:metabolism / Q000648:ultrastructure; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism / Q000648:ultrastructure; D054875:Ubiquitination
chemical_list: D064199:Cdc20 Proteins; C471538:UBA1 protein, human; D025801:Ubiquitin; C577488:CDC20 protein, human; C105156:UBE2C protein, human; C544962:Ube2S protein, human; D044763:Ubiquitin-Conjugating Enzymes; D064173:Anaphase-Promoting Complex-Cyclosome; D044764:Ubiquitin-Activating Enzymes