Multiple anaphase-promoting complex/cyclosome degrons mediate the degradation of human Sgo1.
Shugoshin 1 (Sgo1) protects centromeric sister-chromatid cohesion in early mitosis and, thus, prevents premature sister-chromatid separation. The protein level of Sgo1 is regulated during the cell cycle; it peaks in mitosis and is down-regulated in G1/S. Here we show that Sgo1 is degraded during the exit from mitosis, and its degradation depends on the anaphase-promoting complex/cyclosome (APC/C). Overexpression of Cdh1 reduces the protein levels of ectopically expressed Sgo1 in human cells. Sgo1 is ubiquitinated by APC/C bound to Cdh1 (APC/C(Cdh1)) in vitro. We have further identified two functional degradation motifs in Sgo1; that is, a KEN (Lys-Glu-Asn) box and a destruction box (D box). Although removal of either motif is not sufficient to stabilize Sgo1, Sgo1 with both KEN box and D box deleted is stable in cells. Surprisingly, mitosis progresses normally in the presence of non-degradable Sgo1, indicating that degradation of Sgo1 is not required for sister-chromatid separation or mitotic exit. Finally, we show that the spindle checkpoint kinase Bub1 contributes to the maintenance of Sgo1 steady-state protein levels in an APC/C-independent mechanism.
Karamysheva
Zemfira
Z
Department of Pharmacology, Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, 75390, USA.
Diaz-Martinez
Laura A
LA
Crow
Sara E
SE
Li
Bing
B
Yu
Hongtao
H
D020816:Amino Acid Motifs / Q000502:physiology; D000595:Amino Acid Sequence; D064173:Anaphase-Promoting Complex-Cyclosome; D015703:Antigens, CD; D015820:Cadherins / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002503:Centromere / Q000235:genetics / Q000378:metabolism; D002842:Chromatids / Q000235:genetics / Q000378:metabolism; D016193:G1 Phase / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D016196:S Phase / Q000502:physiology*; D017384:Sequence Deletion; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics / Q000378:metabolism*
D015703:Antigens, CD; C513384:CDH1 protein, human; D015820:Cadherins; D018797:Cell Cycle Proteins; C496644:SGO1 protein, human; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; C584277:BUB1 protein, human; C090464:Bub1 spindle checkpoint protein; D017346:Protein Serine-Threonine Kinases