title: The Cdc20-binding Phe box of the spindle checkpoint protein BubR1 maintains the mitotic checkpoint complex during mitosis.
abstract: The spindle checkpoint ensures accurate chromosome segregation by monitoring kinetochore-microtubule attachment. Unattached or tensionless kinetochores activate the checkpoint and enhance the production of the mitotic checkpoint complex (MCC) consisting of BubR1, Bub3, Mad2, and Cdc20. MCC is a critical checkpoint inhibitor of the anaphase-promoting complex/cyclosome, a ubiquitin ligase required for anaphase onset. The N-terminal region of BubR1 binds to both Cdc20 and Mad2, thus nucleating MCC formation. The middle region of human BubR1 (BubR1M) also interacts with Cdc20, but the nature and function of this interaction are not understood. Here we identify two critical motifs within BubR1M that contribute to Cdc20 binding and anaphase-promoting complex/cyclosome inhibition: a destruction box (D box) and a phenylalanine-containing motif termed the Phe box. A BubR1 mutant lacking these motifs is defective in MCC maintenance in mitotic human cells but is capable of supporting spindle-checkpoint function. Thus, the BubR1M-Cdc20 interaction indirectly contributes to MCC homeostasis. Its apparent dispensability in the spindle checkpoint might be due to functional duality or redundant, competing mechanisms.
authors.affiliation: From the Department of Pharmacology.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Diaz-Martinez
authors.affiliation: From the Department of Pharmacology.
authors.forename: Wei
authors.initials: W
authors.lastname: Tian
authors.affiliation: From the Department of Pharmacology, Howard Hughes Medical Institute, Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390.
authors.forename: Bing
authors.initials: B
authors.lastname: Li
authors.affiliation: From the Department of Pharmacology, Howard Hughes Medical Institute, Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390.
authors.forename: Ross
authors.initials: R
authors.lastname: Warrington
authors.affiliation: From the Department of Pharmacology.
authors.forename: Luying
authors.initials: L
authors.lastname: Jia
authors.affiliation: Department of Biophysics, and.
authors.forename: Chad A
authors.initials: CA
authors.lastname: Brautigam
authors.affiliation: From the Department of Pharmacology, xuelian.luo@utsouthwestern.edu.
authors.forename: Xuelian
authors.initials: X
authors.lastname: Luo
authors.affiliation: From the Department of Pharmacology, Howard Hughes Medical Institute, Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390 hongtao.yu@utsouthwestern.edu.
authors.forename: Hongtao
authors.initials: H
authors.lastname: Yu
mesh_terms: D020816:Amino Acid Motifs; D015703:Antigens, CD; D015820:Cadherins / Q000378:metabolism*; D064199:Cdc20 Proteins / Q000378:metabolism*; D002453:Cell Cycle; D020868:Gene Silencing; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006706:Homeostasis; D006801:Humans; D018386:Kinetochores / Q000378:metabolism; D008938:Mitosis; D011485:Protein Binding; D025941:Protein Interaction Mapping; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D008941:Spindle Apparatus; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D015703:Antigens, CD; C513384:CDH1 protein, human; D015820:Cadherins; D064199:Cdc20 Proteins; D025801:Ubiquitin; C577488:CDC20 protein, human; D005982:Glutathione Transferase; C584277:BUB1 protein, human; D017346:Protein Serine-Threonine Kinases
keywords: APC/C; Cell Cycle; Kinetochore; Mitosis; Mitotic Checkpoint Complex; Protein-Protein Interaction; Spindle Checkpoint; Ubiquitylation (Ubiquitination)