Separase sensor reveals dual roles for separase coordinating cohesin cleavage and cdk1 inhibition.
Complete dissociation of sister chromatid cohesion and subsequent induction of poleward movement of disjoined sisters are two essential events underlying chromosome segregation; however, how cells coordinate these two processes is not well understood. Here, we developed a fluorescence-based sensor for the protease separase that mediates cohesin cleavage. We found that separase undergoes an abrupt activation shortly before anaphase onset in the vicinity of chromosomes. This activation profile of separase depends on the abilities of two of its binding proteins, securin and cyclin B1, to inhibit its protease activity and target it to chromosomes. Subsequent to its proteolytic activation, separase then binds to and inhibits a subset of cyclin B1-cdk1, which antagonizes cdk1-mediated phosphorylation on chromosomes and facilitates poleward movement of sisters in anaphase. Therefore, by consecutively acting as a protease and a cdk1 inhibitor, separase coordinates two key processes to achieve simultaneous and abrupt separation of sister chromatids.
Cancer Institute of the Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koto-ku, Tokyo, Japan.
Norihisa
N
Shindo
Kazuki
K
Kumada
Toru
T
Hirota
D016203:CDC2 Protein Kinase / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000502:physiology*; D002868:Chromosomal Proteins, Non-Histone / Q000502:physiology*; D020090:Chromosome Segregation / Q000502:physiology; D056744:Cyclin B1 / Q000378:metabolism; D004268:DNA-Binding Proteins; D010450:Endopeptidases / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000235:genetics; D006367:HeLa Cells; D006801:Humans; D008856:Microscopy, Fluorescence / Q000379:methods; D009363:Neoplasm Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics* / Q000378:metabolism; D064249:Securin; D064247:Separase; D012854:Sister Chromatid Exchange / Q000502:physiology; D000097722:Cohesins
D016203:CDC2 Protein Kinase; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D056744:Cyclin B1; D004268:DNA-Binding Proteins; D010450:Endopeptidases; D049452:Green Fluorescent Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D064249:Securin; D064247:Separase; D000097722:Cohesins; C534699:CCNB1 protein, human; C429022:RAD21 protein, human; C485184:enhanced green fluorescent protein; C578002:pituitary tumor-transforming protein 1, human; C577987:ESPL1 protein, human