SKP1 Connects Cell Cycle Regulators to the Ubiquitin Proteolysis Machinery through a Novel Motif, the F-Box (original) (raw)
Related papers
Cell, 1995
Cyclin B is degraded at the onset of anaphase by a ubiquitin-dependent proteolytic system. We have fractionated mitotic Xenopus egg extracts to identify components required for this process. We find that UBC4 and at least one other ubiquitin-conjugating enzyme can support cyclin B ubiquitination. The mitotic specificity of cyclin ubiquitination is determined by a 20S ~omplex that contains homologs of budding yeast CDC16 and CDC27, Because these proteins are required for anaphase in yeast and mammalian cells, we refer to this complex as the anaphase-promoting complex (APC). CDC27 antibodies deplete APC activity, while immunopurified CDC27 complexes are sufficient to complement either interphase extracts or a mixture of recombinant UBC4 and the ubiquitin-activating enzyme El. These results suggest that APC functions as a regulated ubiquitin-protein ligase that targets cyclin B for destruction in mitosis.
A 20S complex containing CDC27 and CDC16 catalyzes the mitosis-specific conjugation of ubiquitin to
1995
Cyclin B is degraded at the onset of anaphase by a ubiquitin-dependent proteolytic system. We have fractionated mitotic Xenopus egg extracts to identify components required for this process. We find that UBC4 and at least one other ubiquitin-conjugating enzyme can support cyclin B ubiquitination. The mitotic specificity of cyclin ubiquitination is determined by a 20S ~omplex that contains homologs of budding yeast CDC16 and CDC27, Because these proteins are required for anaphase in yeast and mammalian cells, we refer to this complex as the anaphase-promoting complex (APC). CDC27 antibodies deplete APC activity, while immunopurified CDC27 complexes are sufficient to complement either interphase extracts or a mixture of recombinant UBC4 and the ubiquitin-activating enzyme El. These results suggest that APC functions as a regulated ubiquitin-protein ligase that targets cyclin B for destruction in mitosis.
Role for cyclin-dependent kinase 2 in mitosis exit
Current Biology, 2001
Activity of the cyclin-dependent kinase (cdk) 1-cyclin B 1-cyclin B activity [1]. Exit from mitosis depends on the inactivation of the complex by the complex, also called M phase-promoting factor (MPF), is crucial for mitosis. MPF is required for spindle assembly degradation of cyclin B [2]. Cdk2 is also active during mitosis [3, 4]. In Xenopus egg extracts, cdk2 and chromosome condensation, whereas MPF downregulation by ubiquitin-mediated proteolysis of cyclin B is is primarily in complex with cyclin E, which is stable [5]. At the end of mitosis, downregulation of cdk2-needed to complete mitosis [1, 2]. Sister chromatid separation also requires ubiquitin-mediated proteolysis of securcyclin E activity is accompanied by inhibitory phosphorylation of cdk2 [6]. Here, we show that ins, which inhibit anaphase. The degradation of securins and mitotic cyclins relies upon the cell cycle-regulated cdk2-cyclin E activity maintains cdk1-cyclin B during mitosis. At mitosis exit, cdk2 is inactivated activity of the ubiquitin ligase anaphase-promoting complex/cyclosome (APC/C). This appears to be stimulated prior to cdk1. The loss of cdk2 activity follows and depends upon an increase in protein kinase A (PKA) by cdk1-dependent phosphorylation [2, 7-9]. In addition, at least two WD-40 repeat-containing proteins bind APC/C activity. Prematurely inactivating cdk2 advances the time of cyclin B degradation and cdk1 and are required for its action [2]. In Xenopus egg extracts, the Cdc20/Fizzy homolog is required for APC/C-mediated
E2-C, a cyclin-selective ubiquitin carrier protein required for the destruction of mitotic cyclins
Proceedings of the National Academy of Sciences, 1996
Ubiquitin-dependent proteolysis of the mitotic cyclins A and B is required for the completion of mitosis and entry into the next cell cycle. This process is catalyzed by the cyclosome, an -22S particle that contains a cyclinselective ubiquitin ligase activity, E3-C, that requires a cyclinselective ubiquitin carrier protein (UBC) E2-C. Here we
Developmental Cell, 2003
chromosome congression (den Elzen and Pines, 2001), Stanford University School of Medicine destruction of the anaphase inhibitor securin is required 300 Pasteur Drive for chromosome disjunction and the progression to ana-Stanford, California 94305 phase (Cohen-Fix et al., 1996), and destruction of cyclin B is required for mitotic exit (Murray et al., 1989). How is it that specific APC substrates are not destroyed in Summary S and G2 and yet are sequentially destroyed in M phase to coordinate specific mitotic events? Progression through mitosis occurs because cyclin Surveillance mechanisms or checkpoints that restrict B/Cdc2 activation induces the anaphase promoting specific mitotic events until the completion of earlier complex (APC) to cause cyclin B destruction and mievents contribute to the timing of APC substrate detotic exit. To ensure that cyclin B/Cdc2 does not prestruction. In the best-known example, the spindle asmaturely activate the APC in early mitosis, there must sembly checkpoint (Hoyt et al., 1991; Li and Murray, be a mechanism delaying APC activation. Emi1 is a 1991) restrains the activation of securin destruction to protein capable of inhibiting the APC in S and G2. We delay chromosome separation at anaphase (Cohen-Fix show here that Emi1 is phosphorylated by Cdc2, and et al., 1996) until all chromosomes have established a on a DSGxxS consensus site, is subsequently recogbipolar attachment to the mitotic spindle and congress nized by the SCF TrCP/Slimb ubiquitin ligase and destroyed, to the midline. In the case of the spindle assembly thus providing a delay for APC activation. Failure of checkpoint, the dynamic assembly of a series of factors TrCP-dependent Emi1 destruction stabilizes APC (including Mad1, Mad2, Bub1, and BubR1) that bind and substrates and results in mitotic catastrophe including inactivate Cdc20 (Fang et al., 1998; Tang et al., 2001) centrosome overduplication, potentially explaining delays securin destruction in either normal prometamitotic deficiencies in Drosophila Slimb/TrCP muphase (Geley et al., 2001) or when the spindle is distants. We hypothesize that Emi1 destruction relieves rupted by microtubule depolymerizing agents (Yu, 2002). a late prophase checkpoint for APC activation. Recent evidence shows that the protein Emi1 (Reimann et al., 2001a) inhibits APC Cdc20 activity in interphase Introduction in the Xenopus embryo to prevent destruction of mitotic cyclins. Emi1 can inhibit the APC by blocking the ability To successfully initiate mitosis and bipolar spindle asof the Cdc20 substrate adaptor to bind to its substrates sembly, cells must coordinate the maturation of spindle (Reimann et al., 2001b), although additional mechanisms poles with condensation of the chromosomes, nuclear are possible. Emi1 can also regulate the APC Cdh1 comenvelope breakdown, and prometaphase movements plex in somatic cells to cause the stabilization of S phase of condensed chromosomes on the assembling mitotic regulators including cyclin A at the G1-S transition (Hsu spindle. As the spindle matures, congression of chromoet al., 2002; Reimann et al., 2001b). A similar mechanism somes to the midzone at metaphase triggers chromofor stabilizing cyclin A by the Emi1 homolog Rca1 has some segregation, anaphase movements, and ultibeen demonstrated in Drosophila (Grosskortenhaus and mately cytokinesis. The timing of these complex events Sprenger, 2002). By inhibiting Cdh1 and Cdc20, Emi1 requires the sequential activation of cyclin-dependent defines an interval of cyclin stability and APC inactivity kinases (Cdks) by cyclin A and cyclin B (Minshull et al., from late G1 to early mitosis (Hsu et al., 2002). At the 1990), as well as activation of other mitotic regulatory beginning of this interval, Emi1 is upregulated in rekinases including members of the Aurora, Polo, and sponse to the E2F transcription factor (Hsu et al., 2002). NimA-related (Nek) kinase families. Cyclin B/Cdc2 also At the end of this interval, the Emi1 protein is ubiquitiactivates a critical E3 ubiquitin ligase, the anaphase nated and destroyed (Reimann et al., 2001a) close to promoting complex/cyclosome or APC (Irniger et al., the time when cyclin A is destroyed (Hsu et al., 2002). 1995; King et al., 1995; Lahav-Baratz et al., 1995; Tugen-The ubiquitination enzymes required for Emi1 destrucdreich et al., 1995; reviewed in Harper et al., 2002; Petion have not been identified, although destruction reters, 2002). The APC directs the assembly of multiubiquiquires Cdc2 and not the APC (Reimann et al., 2001a, tin chains on specific substrates and their subsequent 2001b)
A Late Mitotic Regulatory Network Controlling Cyclin Destruction inSaccharomyces cerevisiae
Molecular Biology of the Cell, 1998
Exit from mitosis requires the inactivation of mitotic cyclin-dependent kinase–cyclin complexes, primarily by ubiquitin-dependent cyclin proteolysis. Cyclin destruction is regulated by a ubiquitin ligase known as the anaphase-promoting complex (APC). In the budding yeast Saccharomyces cerevisiae, members of a large class of late mitotic mutants, including cdc15, cdc5, cdc14, dbf2, and tem1, arrest in anaphase with a phenotype similar to that of cells expressing nondegradable forms of mitotic cyclins. We addressed the possibility that the products of these genes are components of a regulatory network that governs cyclin proteolysis. We identified a complex array of genetic interactions among these mutants and found that the growth defect in most of the mutants is suppressed by overexpression of SPO12, YAK1, and SIC1 and is exacerbated by overproduction of the mitotic cyclin Clb2. When arrested in late mitosis, the mutants exhibit a defect in cyclin-specific APC activity that is accompanied by high Clb2 levels and low levels of the anaphase inhibitor Pds1. Mutant cells arrested in G1 contain normal APC activity. We conclude that Cdc15, Cdc5, Cdc14, Dbf2, and Tem1 cooperate in the activation of the APC in late mitosis but are not required for maintenance of that activity in G1.
Defective in Mitotic Arrest 1 (Dma1) Ubiquitin Ligase Controls G1 Cyclin Degradation
Journal of Biological Chemistry, 2012
Background: Dma ubiquitin ligases control the cell cycle in diverse organisms. In humans, these enzymes act as tumor suppressors that prevent aberrant mitosis. Results: Dma1 targets the cyclin Pcl1 for destruction. Conclusion: Dma1 ubiquitin ligase activity controls stability of G 1 cyclins. Significance: Pcl1 is the second reported substrate for Dma1 enzymes. Uncovering new Dma1 substrates could help to elucidate cellular functions of these enzymes. * This work was supported by Spanish Ministry of Science and Innovation Grant BFU 2009-09278, now known as the Ministry of Economy and Competitiveness. □ S This article contains supplemental data. 1 Supported by a postgraduate Junior Faculty fellowship from the Universitat Internacional de Catalunya and l'Obra Social la Caixa.